In this article, we will cover advanced grid functionality and show you how to create an editable grid with cascading dropdowns with a custom header template. Kendo Templates allow us to essentially place widgets inside of a grid widget. Simply put- using these Kendo UI templates allows us to use the grid as a container to hold other Kendo UI widgets.

Like our other articles, we will be using ColdFusion as the backend- however, as we have stated before, Kendo UI is server agnostic and you can use the same techniques learned here with other server-side technologies. 

Please see the example below to see a live demonstration of this code. The code is exhaustive, and we will do our best to cover all essential logical elements here.

Realtime Example

This example is a proof of concept intended to be used by the administrator to determine what categories are used for the CfBlogs Blog Aggregator found at cfblogs.org. The domain dropdown specifies a broader category type, here I am using Lucee and ColdFusion. The category domain is part of the RSS 2 specification and it is an optional category element.  This optional element is rarely used, however, it will allow the Cfblogs logic to potentially determine which subcategory to be used when aggregating the posts.

If the category domain is 'ColdFusion' in this example, the administrator is allowed to select any category that exists in the CfBlogs database. I am grabbing all of the RSS categories when aggregating ColdFusion-related posts; there are thousands of them. If the user selects 'Lucee', I am defaulting to the subcategories found in the Lucee documentation. Once the domain and subcategories have been selected, the user can save the data to the database (however, this functionality is turned off in this example).

To help the users find the blog, there is a custom search engine provided at the top of the page.

Please click on the button below to see the demonstration. This article is quite extensive, you may want to click on the code button and put the window aside to follow along.

Note: this demonstration does not update the database. It is used for demonstration purposes only.

 Example  Code

Using Kendo Templates to Embed Cascading Dropdowns in a Kendo Grid

Introducing Kendo Templates

As we mentioned in previous articles, most of the Kendo Widgets support using templates to extend the widget functionality. The Kendo template is similar to other JavaScript template engines, such as Angular, and is often used to bind data from the server. A template can include logic to display logic or use other JavaScript objects. For more information regarding the Kendo Templates see https://docs.telerik.com/kendo-ui/framework/templates/overview.

You can use a template for nearly every display property in a Kendo Grid. Some of the more popular temples in the Kendo Grid are the row and detail templates. In this example, we will apply a custom toolbar template at the top of the grid instead to apply custom search functionality along with buttons to save and export the data as well as adding a Kend Grid columns.template to embed the URL to the blog name found in the blog column.

Server-Side Queries to Obtain the Data Used in the Dropdowns

The following ColdFusion queries are used to prepare the data for the cascading dropdowns. The getCategoryDomain merely captures two records with the ID and the Category Domain, which are 1 and 3, and 'ColdFusion' and 'Lucee' in this case. The getCategory query captures the categories associated with the Domain Category Id (for example 'AJAX'). 

<cfquery name="getCategoryDomain" datasource="#dsn#">
	SELECT 
		category_domain_id,
		category_domain
	FROM category_domain
	WHERE category_domain <> 'Kendo UI'
	ORDER BY category_domain
</cfquery>

<cfquery name="getCategory" datasource="#dsn#">
	SELECT 
		category_id,
		category_domain_ref as category_domain_id,
		category
	FROM category
	ORDER BY category
</cfquery>

Changing Style Properties of the Kendo Grid

Use the k-grid class to change the font and the height of the rows. The k-grid class is quite extensive and can also be used for other properties as well. Be aware if you use the k-grid class, it will affect the display of all of the grids on the page.

<style>
	.k-grid {
		font-size: 12px;
	}
	.k-grid td {
		line-height: 2em;
	}
</style>

Empty DIV container to Hold the Kendo Grid

Nearly all of the Kendo Widgets need to have a DIV element to contain the elements of the widget. You can create a static DIV like we have done here, or create the DIV dynamically as we have done when creating a dynamic Kendo Window.

<!--- Empty iv container for the grid. ---> 
<div id="feedsGrid"></div>

Kendo Grid Custom Header

Our feedGridToolbar custom header has buttons to export the grid data to Excel and PDF and has a custom search interface to allow the user to quickly find records. 

External Kendo Templates

In this example, we will use a Kendo external template. These templates are embedded in JavaScript with the type of 'text/x-kendo-template'. 

Custom Export PDF and Excel Buttons

It should be noted that the "k-button k-button-icontext k-grid-pdf" and "k-button k-button-icontext k-grid-excel" classes are used to create custom buttons to invoke Kendo's native saveAsPdf and saveAsExcel methods. Clicking on these buttons will either save the contents of the grid to PDF or Excel. Other helpful custom classes that you can apply to custom buttons are:

• k-grid-add creates a button with a plus and will invoke the addRow method
• k-grid-edit fires the edit method to edit the rows within the grid
• k-grid-cancel cancels any edits in progress

  ---

Note: typically, if you don't want a custom toolbar, you can simply add the following code in the Kendo grid initialization to embed export to PDF and Excel capabilities along with a save button and search functionality.

toolbar: ["pdf", "excel", "save", "search"],

This will replicate the functionality that we have provided using the custom toolbar templates.

Note: the default search input functionality only works with 2019 R3 2019.3.917 release and greater.

Implementing a Custom Kendo Grid Search Interface 

We are using custom JavaScript logic to handle the search interface. It should be noted that built-in search functionality is already baked into the grid that filters records on the client, however, there are advantages when using a customized search interface that returns search results as we are doing here.

When the search button is clicked, the onFeedsGridSearch() method will be invoked which will query the database on the server using the entered search string to retrieve the relevant records. The circular refresh button calls the refreshFeeds() method which will refresh the grid. We will cover these two methods below.

<!--- Grid toolbar template --->
<script type="text/x-kendo-template" id="feedsGridToolbar">
	<div class="toolbar" style="margin: auto; float: left;">
		<!--- Default Kendo UI buttons for PDF and Excel export. Note: when using ColdFusion, we need to escape any pound symbols in the template with a backslash --->
		<a class="k-button k-button-icontext k-grid-pdf" style="margin: auto;" href="#"><span class="k-icon k-i-pdf"></span>Export to PDF</a>
		<a class="k-button k-button-icontext k-grid-excel" id="feedGridExcelExport" href="#"><span class="k-icon k-i-excel"></span>Export to Excel</a>
	</div>

	<span class="toolbar" style="margin: auto; float:right; <cfif not session.isMobile>padding-right:10px;</cfif>">

		<!--- Search ---> 
		<label class="category-label" for="feedsGridSearchField">Search:</label>
		<input type="text" id="feedsGridSearchField" class="k-textbox" style="width: <cfif session.isMobile>200<cfelse>400</cfif>px; padding :5px;"/>
		<a href="javascript:onFeedsGridSearch();" aria-label="Search" class="k-link k-menu-link"><span class="fa fa-search" style="font-size:1em; padding :5px;"></span></a>

		<cfif not session.isMobile>
		<!--- Refresh --->
		<a href="#" class="k-pager-refresh k-link k-button k-button-icon" title="Refresh" onClick="refreshFeedsGrid();" style="padding :5px;"><span class="k-icon k-i-reload" onClick="refreshBlogCategoryGrid();"></span></a>
		</cfif>
	</span>
</script>

Custom Search JavaScript Methods used by the Grid

The onFeedsGridSearch Method

This method simply takes the string that was entered by the user and passes it to the createSearchFilter method. These two methods can be consolidated, however, I separated them into two distinct methods as I may want to use the createSearchFilter method in other client-side interfaces to modify the grid.

The createSearchFilter method

This method takes a search term string and applies the filters to send it to the Kendo data source. The Kendo filters accept an array of items, and we will populate the new filter array using jQuery's push method. After the filter array is populated, we will apply it to the Kendo grid data source that is used to repopulate the Kendo grid.

function onFeedsGridSearch(){
	// Extract the search term
	var searchTerm = $("#feedsGridSearchField").val();
	// Invoke the createSearchFilter function
	createSearchFilter(searchTerm);
}//function

// Grid filters
function createSearchFilter(searchTerm){
	// Get a reference to the grid.
	var grid = $("#feedsGrid").data("kendoGrid");
	// Instantiate the filter object as an array
	$filter = new Array();
	// Build the filters with the search term
	if(searchTerm){
		// Populate the array of filters
		$filter.push({ field: "name", operator: "contains", value: searchTerm });
		$filter.push({ field: "description", operator: "contains", value: searchTerm });
		$filter.push({ field: "url", operator: "contains", value: searchTerm });
		// Refresh the data with the new filters.  
		grid.dataSource.filter({logic: "or", filters: $filter}); 
	}//if
}//function

Manually Refreshing the Kendo Grid

The circular button on the right of the custom header allows the user to manually refresh the grid. Here we are clearing the search input using jQuery, removing any previously applied filters, refreshing the data source using the datasource read method, and refreshing the Kendo grid.

function refreshFeedsGrid(){
	// Clear any prevous search term in the search input
	$("#feedsGridSearchField").val('');
	// Remove the filters
	$("#feedsGrid").data("kendoGrid").dataSource.filter({});
	// Refresh the datasource
	$("#feedsGrid").data("kendoGrid").dataSource.read();
}

The Logic for the First Cascading Category Domain Kendo Dropdown

Create the Local JavaScript JSON Variable for the Parent Dropdown

For performance reasons, all cascading dropdowns within a grid should use local binding. You can use server-side binding, however, since the grid can contain thousands, or potentially millions of records, the performance would be very slow and the interface would appear to be buggy.

For the parent category domain dropdown, we are creating a local JavaScript JSON variable to hold the dropdown values. Currently, this is either ColdFusion or Lucee. The output of this JSON is "var categoryDomainDataArray = [{ "category_domain_id":1,"category_domain":"ColdFusion"},{ "category_domain_id":2,"category_domain":"Lucee"}];"

/*  Static data arrays are needed for the dropdowns within a grid. Putting the dropdown data in a datasource declaration is not sufficient as it loads the data from the server on every click making the dropdowns within a grid very slow. */
var categoryDomainDataArray = [<cfoutput query="getCategoryDomain">{ "category_domain_id":#category_domain_id#,"category_domain":"#category_domain#"}<cfif getCategoryDomain.currentRow lt getCategoryDomain.recordcount>,</cfif></cfoutput>];
//Note: this local js variable is not declared as a separate datasource for efficiency. When the grid is refreshed via the read method, having this in it's own datasource is problematic with large datasets.

Create a JavaScript Function to Initialize the Parent Kendo Dropdown

If you have been following our previous Kendo UI articles, you should recognize that the code to initialize the cascading dropdowns is quite similar. The main difference is that the initialization here is wrapped inside a JavaScript function. You should note that the serverFiltering argument is set to true which typically means that the filtering takes place on the server- however, this is not the case as our dataSource is using the local JavaScript JSON array that we just created. We are also using an onClose and onChange to invoke the onDomainChange method which is used to populate our child category dropdown.

/* This function is used by the template within the domain column in the grid */
function domainCategoryDropDownEditor (container, options) {
	$('<input required data-text-field="category_domain" data-value-field="category_domain_id" data-bind="value:' + options.field + '"/>')
	.appendTo(container)
	.kendoComboBox({
		serverFiltering: true,
		placeholder: "Select domain...",
		dataTextField: "category_domain",
		dataValueField: "category_domain_id",
		dataSource: categoryDomainDataArray,
		// Invoke the onDomain change methd to filter the category when the domain has been selected.
		close: onDomainChange,
		change: onDomainChange
	});//...kendoComboBox
}//...function

Create a Function to Display the Initial Values in the Parent Domain Category Dropdown

This function will populate the initial category domain values in the grid (which will be ColdFusion or Lucee). The getCategoryDomain function simply loops through the categoryDomainArray JSON that we created above and compares the domainId to the category_domain_ref returned from the server by the Kendo DataSource. When the two values match, it returns the value back. 

// Function to display the initial domain in the grid.
// !! Notes: 1) the categoryDomainRef is coming from the query on the server that is populating the grid, 2) the dropdown functions and it's datasource must be outside of the document.ready scope.
function getCategoryDomainDropdown(category_domain_ref) {
	// Set the default var.
	var domain = '';
	// Loop thru the local js variable.
	for (var i = 0, length = categoryDomainDataArray.length; i < length; i++) {
		if (categoryDomainDataArray[i].category_domain_id == category_domain_ref) {
			// Set the global labelValue var in order to return it properly to the outer function. This should either be null or the proper value.
			domain=categoryDomainDataArray[i].category_domain;
		}//if (categoryDomainDataArray[i].category_id == category_id)...
	}//for...
	return domain;
}//...function

Create the Parent Domain Category Filter

The following function is used when filtering the data by clicking on the domain category column in the grid. This function indicates that the filter should search our categoryDomainArray and should return the category_domain for the dropdown label and set the category_domain_id for the value of the field. Note: this step is only needed when you explicitly set the grid's filterable argument to true.

// Filter for the dropdown. Note: the filterMenuInit event is raised when the filter menu is initialized.
function categoryDomainDropdownFilter(element) {
	element.kendoComboBox({
		serverFiltering: true,
		dataSource: categoryDomainDataArray,
		filter: "contains",
		dataTextField: "category_domain",
		dataValueField: "category_domain_id"
	})//...element.kendoComboBox;
}//...function categoryDomainDropdownFilter(element)

Create the Parent onChange Function

The onDomainChange JavaScript function will get a reference to the category child dropdown and filter the category by the categoryDomain that was selected by the user. Here we are using the contains operator, which works in this case as every domainId is unique. If the IDs were not unique, we would change the operator to "equals".

// On change function that will filter the category dropdown list if a domain was selected.
function onDomainChange(e){
	// Create a reference to the next dropdown list.
	var category = $("#category").data("kendoComboBox");
	// Filter the category datasource
	category.dataSource.filter( {
	  field: "category_domain_id", //  
	  value: this.value(),
	  operator: "contains"
	});
}//function onDomainChange(e)...

The Logic for the Last Child Cascading Category Kendo Dropdown

For the child cascading menu, we are going to repeat all of the steps used to create the first category domain dropdown that we just performed, however, we can omit the last onChange step unless there is another dependent child dropdown, which is not the case here. Much of our logic is identical, but I will identify the main differences.

Create the Local JavaScript JSON Variable for the Child Dropdown

The logic here is nearly identical to the domainCategoryArray that we created. The main difference is that we are also including the category_domain_id, along with the category_id and the category. For any child dropdowns, you must include a value that is found in the parent dropdown in order to associate the dropdowns. Here, the category_domain_id will be the association that we will use to filter this child dropdown.

var categoryArray = [<cfoutput query="getCategory">{ "category_domain_id": #category_domain_id#, "category_id": #category_id#, "category":"#category#"}<cfif getCategory.currentRow lt getCategory.recordcount>,</cfif></cfoutput>];

Create a JavaScript Function to Initialize the Kendo Child Dropdown

The ComboBox initialization is nearly identical to its parent, here we are assigning the category as the dropdown label and the category_id as the dropdown value. We are also omitting the onChange logic as this is the last dependent dropdown. If there are other child dropdowns dependent upon the selection of this value, the onChange logic must be included.

// This function is invoked inside of the grid template to populate the initial values for the first category dropdown. This dropdown is independent of the 2nd category dropdown
function categoryDropDownEditor(container, options) {
	$('<input id="category" required data-text-field="category" data-value-field="category_id" data-bind="value:' + options.field + '"/>')
	.appendTo(container)
	.kendoComboBox({
		placeholder: "Select category...",
		dataTextField: "category",
		dataValueField: "category_id",
		dataSource: categoryArray,
	});//...kendoComboBox
}//...function

Create a Function to Display the Initial Values in the Category Child Dropdown

Again, this logic is identical to the parent other than we are using the category_id and category instead of the domain category information. 

function getCategoryDropdown(category_id) {
	// Set the default var.
	var category = '';
	// Loop thru the local js variable.
	for (var i = 0, length = categoryArray.length; i < length; i++) {
		if (categoryArray[i].category_id == category_id) {
			// Set the global labelValue var in order to return it properly to the outer function. This should either be null or the proper value.
			category=categoryArray[i].category;
		}//if (categoryArray[i].category_id == category_id)
	}//for...
	return category;
}//...function

Create the Child Category Filter

This is identical to the parent menu other than using the category_id and category that will be used when the user filters the data. This code is not necessary if the filterable argument was not explicitly set to true in the grid declaration.

function categoryDropdownFilter(element) {
	element.kendoComboBox({
		dataSource: categoryArray,
		filter: "contains",
		dataTextField: "category",
		dataValueField: "category_id",
		cascadeFrom: "category"
	})//...element.kendoComboBox;
}//...function categoryDropdownFilter(element)

Wrap the Kendo DataSource and Grid Initialization with a Document Ready Block

Most of the Kendo Widgets, especially the Kendo Grid, should be placed in jQuery's document-ready scope in order for the widgets to function. However, you must also place any universal JavaScripts that need to be invoked outside of the document-ready scope, otherwise, your JavaScripts will not be available outside of the ready block. Typically I wrap the ready block around the Kendo DataSource and the widget initialization code and keep all other scripts outside of the ready block. If your Kendo Grids are not initializing, this is one of the first things that I check and I will always try to place a comment at the end of the ready block.

$(document).ready(function(){
... code goes here
});//document ready

Create the Kendo DataSource

The Kendo DataSource here is nearly identical to the data source that we created in our last article showing you how to create the data source for an editable grid. The only difference is that here we are wanting to return information to create the category domain and category. There is nothing unique that we need here in order to use cascading dropdowns. Please see https://gregoryalexander.com/blog/#mcetoc_1gkr406c31 for more information.

// Create the datasource for the grid
feedsDs = new kendo.data.DataSource({
	// Determines which method and cfc to get and set data.
	transport: {
	   read:  {
			url: "/blog/demo/Demo.cfc?method=getDemoFeeds", // the cfc component which processes the query and returns a json string. 
			dataType: "json", // Use json if the template is on the current server. If not, use jsonp for cross domain reads.
			method: "post" // Note: when the method is set to "get", the query will be cached by default. This is not ideal. 
		},
		// The create method passes the json like so: models: [{"id":"","name":"","description":"sadfas","url":"","blogsoftware":"","demo_notes":"asdfa","demo_active":false}]
		create: {
			url: "/blog/demo/Demo.cfc?method=saveBlogReqestViaGrid&action=insert",
			dataType: "json",
			method: "post"
		},
		// The update function passes all of the information in the grid in a models JSON string like so: [{"total":147,"demo_notes":"","description":"Jochem's tech exploits due to fork","blogsoftware":"http://wordpress.org/?v=2.7","recentposts":0,"id":48,"rssurl":"http://jochem.vandieten.net/feed
","demo_description":"Jochem's tech exploits","demo_active":false,"url":"http://jochem.vandieten.net
","name":""it could be bunnies""}]
		update: {
			url: "/blog/demo/Demo.cfc?method=saveBlogReqestViaGrid&action=update",
			dataType: "json",
			method: "post"
		},	
		destroy: {
			url: "/blog/demo/Demo.cfc?method=saveBlogReqestViaGrid&action=delete",
			dataType: "json",
			method: "post"
		},	
		// The paramterMap basically strips all of the extra information out of the datasource for the grid display. YOu must use this when you are using an editible Kendo grid otherwise strange behavior could occur.
		parameterMap: function(options, operation) {
			if (operation !== "read" && options.models) {
				return {models: kendo.stringify(options.models)};
			}
		}
	},
	cache: false,
	batch: true, // determines if changes will be send to the server individually or as batch. Note: the batch arg must be in the datasource declaration, and not in the grid. Otherwise, a post to the cfc will not be made. 
	pageSize: 10, // The number of rows within a grid.
	schema: {
		model: {
			id: "id", // Note: in editable grids- the id MUST be put in here, otherwise you will get a cryptic error 'Unable to get value of the property 'data': object is null or undefined'
			fields: {
				// We are using simple validation to require the blog name, desc, url and rss url. The other fields are not required. More elaborate validation examples will be provided in future blog articles. It is somewhat counter intuitive IMO that these validation rules are placed in the Kendo DataSource. 
				name: { type: "string", editable: true, nullable: false, validation: { required: true } },
				description: { type: "string", editable: true, nullable: false, validation: { required: true } },
				url: { type: "string", editable: true, nullable: false, validation: { required: true } },
				rss_url: { type: "string", editable: true, nullable: false, validation: { required: true } },
				site_image: { type: "string", editable: true, nullable: false, validation: { required: false } },
				// Note: the following two cascading menu fields need to have a default value 
				domain_category: { type: "string", editable: true, nullable: false, validation: { required: false }, defaultValue: 0 },
				// The category is dependent upon the domain category. Each category has a domain category id
				category: { type: "string", editable: true, nullable: false, validation: { required: false }, defaultValue: 0 },
				request_approved: { type: "boolean", editable: false, nullable: false, validation: { required: false } },
			}//fields:
		}//model:
	}//schema
});//feedsDs = new kendo.data.DataSource

Initialize the Kendo Grid

Like the Kendo DataSource, the grid initialization is quite similar to the grid initialization in our previous article, However, this script calls the CfBlogs Eernal Kendo Template that we created at the beginning of this article for the header. The category_domain and category columns in the grid have extra logic required to make our cascading dropdowns.

Handling the Parent category_domain Dropdown

For our first domain_category dropdown, there are three settings that are unique to the dropdown.

• For the columns.template argument, we are invoking the getCategoryDropdown method to populate the initial read-only values when the grid is loaded.
• The columns.editor argument is invoking the categoryDomainEditor JavaScript function that we created to initially populate the control once the edit button on the far right of the grid has been clicked. 
• The columns.filter argument is invoking the categoryDomainDropdownFilter function. We are also modifying the filtering capability of the domain dropdown to "equal" or "not equal to".

Handling the Child Category Dropdown

• The columns.template argument, we are invoking the getCategoryDropdown method to populate the initial read-only values when the grid is loaded.
• The columns.editor argument is invoking the categoryDropDownEditor JavaScript function that we created to initially populate the control once the edit button on the far right of the grid has been clicked. 
• The columns.filter argument is invoking the categoryDropdownFilter function. We are also modifying the filtering capability of the domain dropdown to "equal" or "not equal to".

  ---

$("#feedsGrid").kendoGrid({
	dataSource: feedsDs,
	// Edit arguments
	editable: "inline", // use inline mode so both dropdownlists are visible (required for this type of cascading dropdown)
	// Header 
	headerTemplate: 'CfBlogs',
	// Toolbars. You can customize each button like the excel button below. The importExcel button is a custom button, and we need to wire it up to a custom handler below.
	toolbar: kendo.template($("#feedsGridToolbar").html()),
	excel: {
		allPages: true
	},
	// General grid elements.
	height: 660,// Percentages will not work here.
	filterable: true,
	columnMenu: true,
	groupable: true,
	sortable: {
		mode: "multiple",
		allowUnsort: true,
		showIndexes: true
	},
	allowCopy: true,
	reorderable: true,
	resizable: true,
	pageable: {
		pageSizes: [15,30,50,100],
		refresh: true,
		numeric: true
	},
	columns: [{
		// Columns
		field:"id",
		title: "I.D.",
		hidden: true,
		filterable: false
	}, {
		field:"name",
		title: "Blog",
		filterable: true,
		width: "15%",
		template: '<a href="#= url #">#= name #</a>'
	}, {
		field:"description",
		title: "Description",
		filterable: true,
		width: "20%"
	}, {
		field:"url",
		title: "Blog URL",
		filterable: true,
		width: "15%"
	}, {
		field:"domain_category",
		width: "10%",
		editor: domainCategoryDropDownEditor,
		// The template should be a function that matches the id's and returns the title.
		template: "#=getCategoryDomainDropdown(category_domain_ref)#",//The method that gets the id by the name that was selected.
		title: "Domain",
		filterable: {
			extra: false,// Don't show the full filter menu
			ui:categoryDomainDropdownFilter,
			operators: {
				string: {
					eq: "is equal to",
					neq: "is not equal to"
				}//..string
			}//...operators
		}//...filterable
	}, {
		field:"category",
		width: "12%",
		editor: categoryDropDownEditor,
		// The template should be a function that matches the id's and returns the title.
		template: "#=getCategoryDropdown(category_id)#",//The method that gets the id by the name that was selected.
		title: "Category",
		filterable: {
			extra: false,// Don't show the full filter menu
			ui:categoryDropdownFilter,
			operators: {
				string: {
					eq: "is equal to",
					neq: "is not equal to"
				}//..string
			}//...operators
		}//...filterable
	}, { 
		command: [
			// Opens the editable columns 
			{ name: "edit", text: "Edit" },
			// Cancels the operation
			{ name: "destroy", text: "Cancel" }
		],
		title: " ",
		width: "12%" 
	}
	]// columns:

});// $("#feedsGrid").kendoGrid({

Further Reading

• Add Cascading DropDownList Editors
• cascading-dropdown-editors.md

The Kendo Grid is one of the most advanced HTML grid libraries. In this article, we will cover standard out-of-the-box grid functionality and show you how to use the Kendo Grid to view and edit records with ColdFusion on the backend. However, Kendo UI is server agnostic and you can use the same techniques learned here with other server-side technologies.

Implementing an Editable Kendo Grid

My CFBlogs blog aggregator follows around 150 ColdFusion-related blogs. In this example, we will recreate the Kendo grid found at https://www.cfblogs.org/?blogs and add a few additional columns to allow users to save data using a Kendo UI grid.

Out-of-the-box, Kendo UI provides rich functionality with most of its widgets without having to write custom code that is triggered by events. Here, we are using Kendo's extensive built-in functionality to create an editable grid with search and filter capabilities.

Example Demonstration and Client Side Code

This example will allow the user to interact with the capabilities of the Kendo UI Grid.

We will be using standard out-of-the-box functionality to create this first draft interface allowing the public to request that we add their own blog to the CFBlogs aggregator. In later articles, we will improve upon these interfaces in order to show you the benefits of the Kendo UI and the Kendo grid. Click the button below to see the Kendo Grid in action. 

This article is quite detailed and lengthy, I recommend opening up both the demonstration and the client side code when reading the article to make more sense of it.

Note: You can click on the pin icon on the top right of the window if you want to keep the window stationary when scrolling.

  Demonstration   Client Side Code 

General Considerations when using the Kendo Grid

Use a Large Screen Width

You should use a large screen width if possible. The Kendo Grid is used to visualize and interact with large amounts of data. There are techniques, such as using nested rows, to condense the width of the grid, however, it is most effective when used on wider devices. You should display as many relevant columns as you can in order to allow users to better interact with the data.

Enable Paging or Use Grid Virtualization

Adding paging to the grid restricts the number of rows in the grid, however, it allows the users to click on the paging buttons at the bottom of the grid to view the next x number of records. This provides better grid performance as well as condenses the number of records that are presented to the user at one time.

You can also implement grid virtualization to limit the number of records when dealing with large amounts of data. We will cover grid virtualization in future articles.

Allow the Users to Filter and Search for Relevant Data

It is important to allow the users to get to the relevant records as fast as possible. Not only does this have the positive benefit of saving time and frustration for the user, but it also limits the quantity of the records improving overall grid performance. In this article, we will show you how to implement out-of-the-box client-side search functionality along with sophisticated grid filters to allow users to seek relevant records.

Validate the Data on Both the Client and Server

Like most all of the other HTML5 widgets, you should validate data both on the client and the server. Here we will introduce the Kendo UI validator and provide basic examples of how to perform basic validation on the client and server. 

Differences Between Editable and View-Only Grids

Differences Between Read-Only and Editable Grids on the Client Side

The major differences between an editable grid and a view-only grid that we previously covered are that the editable grid has extra logic placed in the Kendo Datasource declaration. I am not quite sure why Telerik chose to use extra logic to edit a record in the Kendo DataSource, including client-side validation for example, however, it is important to remember that this logic needs to be placed inside the Kendo DataSource. 

There are some other minor logic differences outside of the Kendo DataSource as well and will cover these below.

Differences Between Read-Only and Editable Grids on the Server

The logic on the server handling a view-only grid is simple- the server needs to simply query the database and return the data as JSON. With an editable grid, we need to inspect and understand how the Kendo DataSource sends the data to the server and have additional arguments to determine how to save the data into the database. 

Client-Side Logic

The KendoDataSource Explained

As we have previously mentioned in this article, most of the logic that pertains to editing the grid needs to be embedded into the Kendo DataSource. This includes configuring whether the columns are editable as well as the validation rules. We also need to configure the settings for the background AJAX requests to the server to modify the data.

We will try to cover most of the essential details of the code that is the basis for the demonstration example below. This is a fairly comprehensive explanation but it should make more sense when you peruse the code example further below.

Kendo DataSource Transport Arguments

We need to configure the background AJAX requests in the Kendo DataSource transport. We will set the URLs pointing to the service endpoints for our read, update and destroy operations.

In this example, the service endpoint for all operations is the Demo.cfc ColdFusion component.  However, the methods are different- for read operations, we are calling the getDemoFeeds() method, and the udate, create, and destroy methods are calling the saveBlogReqestViaGrid and we are passing an additional action argument in the URL. The action URL argument will determine if we will update, insert or delete records in the database. This is a ColdFusion component, however, you should be able to adapt the code for other technologies as well. We will elaborate on the ColdFusion server-side logic later in the article.

Note that the name of the create, update and destroy methods must correspond to the toolbar "create", "update", and "destroy" strings in the toolbar's array in the code in the grid configuration below.

Finally, the transport configuration needs to include the paramaterMap configuration. The parameterMap transforms the data for read operations into JSON and this parameterMap string should always be used when using editable grids, otherwise, the excess information in the Kendo DataSource object will interfere with read operations.

Kendo DataSource Batch Argument

The batch argument determines if changes will be sent to the server individually or as a batch. I typically always set this to true as it only makes one AJAX request to update the data instead of sending multiple requests to the server.

Kendo Datasource Field Arguments

In this example, we will use field arguments to determine whether the column is editable and if the values can be null, and set the validation rules to make sure that certain columns are filled out. 

The field type argument specifies the data type of the field. The type can be string, number, boolean, or date. You can also use object but we will not cover that here.

Editable determines if the user can make changes to the column. This is a true or false value. Nullable is similar and determines if a null value can be passed to the server.

Validation can take an array of arguments. We also use this to configure custom validation rules with the Kendo Validator. We will cover this in detail in a future article but in this example, we are only setting whether a column value is required. If the column is required, a message will be displayed on the client side when nothing was filled out by the user.

Kendo DataSource Code

feedsDs = new kendo.data.DataSource({
	// Determines which method and cfc to get and set data.
	transport: {
	   read:  {
			url: "/blog/demo/Demo.cfc?method=getDemoFeeds", // the cfc component which processes the query and returns a json string. 
			dataType: "json", // Use json if the template is on the current server. If not, use jsonp for cross domain reads.
			method: "post" // Note: when the method is set to "get", the query will be cached by default. This is not ideal. 
		},
		// The create method passes the json like so: models: [{"id":"","name":"","description":"sadfas","url":"","blogsoftware":"","demo_notes":"asdfa","demo_active":false}]
		create: {
			url: "/blog/demo/Demo.cfc?method=saveBlogReqestViaGrid&action=insert",
			dataType: "json",
			method: "post"
		},
		// The update function passes all of the information in the grid in a models JSON string like so: [{"total":147,"demo_notes":"","description":"Jochem's tech exploits due to fork","blogsoftware":"http://wordpress.org/?v=2.7","recentposts":0,"id":48,"rssurl":"http://jochem.vandieten.net/feed
","demo_description":"Jochem's tech exploits","demo_active":false,"url":"http://jochem.vandieten.net
","name":""it could be bunnies""}]
		update: {
			url: "/blog/demo/Demo.cfc?method=saveBlogReqestViaGrid&action=update",
			dataType: "json",
			method: "post"
		},	
		destroy: {
			url: "/blog/demo/Demo.cfc?method=saveBlogReqestViaGrid&action=delete",
			dataType: "json",
			method: "post"
		},	
		// The parameterMap basically strips all of the extra information out of the datasource for the grid display. You must use this when you are using an editable Kendo grid otherwise strange behavior could occur.
		parameterMap: function(options, operation) {
			if (operation !== "read" && options.models) {
				return {models: kendo.stringify(options.models)};
			}
		}
	},
	cache: false,
	batch: true, // determines if changes will be sent to the server individually or as batch. Note: the batch arg must be in the datasource declaration, and not in the grid. Otherwise, a post to the cfc will not be made. 
	pageSize: 15, // The number of rows within a grid.
	schema: {
		model: {
			id: "id", // Note: in editable grids- the id MUST be put in here, otherwise you will get a cryptic error 'Unable to get the value of the property 'data': object is null or undefined'
			fields: {
				// We are using simple validation to require the blog name, desc, url and rss url. The other fields are not required. More elaborate validation examples will be provided in future blog articles. It is somewhat counterintuitive IMO that these validation rules are placed in the Kendo DataSource. 
				name: { type: "string", editable: true, nullable: false, validation: { required: true } },
				description: { type: "string", editable: true, nullable: false, validation: { required: true } },
				url: { type: "string", editable: true, nullable: false, validation: { required: true } },
				rss_url: { type: "string", editable: true, nullable: false, validation: { required: true } },
				site_image: { type: "string", editable: true, nullable: false, validation: { required: false } },
				blog_software: { type: "string", editable: true, nullable: false, validation: { required: false } },
				notes: { type: "string", editable: true, nullable: true, validation: { required: false } },
				request_approved: { type: "boolean", editable: false, nullable: false, validation: { required: false } },
			}//fields:
		}//model:
	}//schema
});//feedsDs = new kendo.data.DataSource

Kendo Grid Configuration Explained

The Grid initialization is nearly identical to read-only grids, the main difference being the buttons on the toolbar (or custom toolbar template) that allow the user to edit and insert records into the grid. We are also going to introduce how to configure the toolbar to export the grid data into Excel or PDF and provide the standard out-of-the-box client-side search interface.

The Kendo UI Grid Toolbar

The Grid toolbar is at the top of the grid and can be configured with buttons and other custom elements and can be configured in multiple ways. If you're not using a custom Kendo UI template, the toolbar for the grid takes either a single string or an array of arguments to provide built-in functionality.

Every toolbar string will render a button on the toolbar. If the argument is not a built-in argument such as "excel", you need to also have a custom method in the dataSource transport in order to invoke a  custom Javascript method.

We will explain the built-in arguments below.

Exporting Kendo UI Grid Data to PDF and Excel

Typically, if you are not using a custom toolbar, you can simply add the following code in the Kendo grid initialization to embed export to PDF and Excel capabilities.

toolbar: ["pdf", "excel"],

There are further configuration options for Excel export capability. Additional Excel configuration arguments are allPages, which allows the grid to export data from the entire grid, and fileName. A Typical example is shown below.

excel: { 
	allPages: true,
	fileName: "Blogs.xlsx"
}

Toolbar Arguments to Provide Grid Editing Capabilities 

The following arguments can be applied to the toolbar to render the edit, insert, and cancel buttons that are used to edit records. These buttons will invoke the same methods that were created in the transport section in the Kendo DataSource to insert and save any edited records.

The create button will add a row to the grid allowing the user to add a new record, the save button is used to save any edited records within the grid, and the cancel button allows the user to back out of any changes.

"create", "save", "cancel"

Toolbar Argument to Render a Client-side Search Engine Interface

The following argument will create a search panel interface allowing the users to search for any of the records. 

"search"

If you want to fine-tune the search parameters, you can specify which columns are being searched and provide the search operators like so:

toolbar: ["search"],
search: {
	fields: [
		{ name: "name", operator: "eq" },
		{ name: "description", operator: "contains" },
		{ name: "url", operator: "contains" },
	]
},

Note: the default search input functionality only works with 2019 R3 2019.3.917 release and greater.

Available Kendo UI Search Operators

The operators, for both the search panel as well as the column filters, are:

• eq (equal to)
• neq (not equal to)
• lt (less than)
• isnull (is null)
• isnotnull (is not null)
• gt (greater than)
• gte (greater than or equal to)
• lt (less than)
• lte (less than or equal to)
• isempty (is an empty string)
• isnotempty (is not an empty string)
• contains 
• doesnotcontain (does not contain)
• startswith 
• doesnotstarwith
• endswith
• doesnotendwith

Putting the toolbar options together in our example we have the following which allows for Excel and PDF Export, buttons to create save, and cancel records, and an out-of-the-box client-side search interface.

toolbar: ["pdf", "excel", "create", "save", "cancel", "search"],
excel: {
	allPages: true
},

The columnmenu Configuration 

When the columnmenu argument is set to true, Kendo UI will render a menu that is available by clicking on the ellipsis to the right of the column text. The user can use this menu to filter the grid (see below), provide sorting, and determine which columns are visible. I recommend setting this to true unless there is a reason to disable it.

The filterable Configuration 

The filterable argument provides search filters for all of the grid columns. There are multiple options to filter the results. Out of the box, there are nearly a dozen different operators such as "equals", "contains" etc. The filters configuration also allows the user to select which columns to show in the grid allowing them to remove columns that they don't care about. The best way to comprehend the filters is to take a look at our example, click on the ellipsis to the right of any column, and choose filter. I will provide a few screenshots of our example. In my interfaces, I always include the filters using filterable: true.

The groupable Configuration 

If you set the groupable argument to true, Kendo UI will create a new ribbon underneath the toolbar to allow the grid columns to be grouped. If nothing is already grouped, the ribbon will display 'Drag a column header and drop it here to group by that column'. The user can select and drag any column to this ribbon in order to group the data by the selected column, and multiple columns can be grouped. Note that the grouping takes place on the client side- there will be no interaction with the server.

sortable: {
	mode: "multiple",
	allowUnsort: true,
	showIndexes: true
},

pageable: {
	pageSizes: [15,30,50,100],
	refresh: true,
	numeric: true
},

$("#feedsGrid").kendoGrid({
	dataSource: feedsDs,
	editable: true,
	// Toolbars. 
	toolbar: ["pdf", "excel", "create", "save", "cancel", "search"],
	excel: {
		allPages: true
	},
	// General grid elements.
	height: 740,// Percentages will not work here.
	filterable: true,
	columnMenu: true,
	groupable: true,
	sortable: {
		mode: "multiple",
		allowUnsort: true,
		showIndexes: true
	},
	allowCopy: true,
	reorderable: true,
	resizable: true,
	pageable: {
		pageSizes: [15,30,50,100],
		refresh: true,
		numeric: true
	},
	columns: [{
		// Columns
		field:"id",
		title: "I.D.",
		hidden: true,
		filterable: false
	}, {
		field:"name",
		title: "Blog",
		filterable: true,
		width: "17%",
		template: '<a href="#= url #">#= name #</a>'
	}, {
		field:"description",
		title: "Description",
		filterable: true,
		width: "19%"
	}, {
		field:"url",
		title: "Blog URL",
		filterable: true,
		width: "15%"
	}, {
		field:"rss_url",
		title: "RSS URL",
		filterable: true,
		width: "15%"
	}, {
		field:"blog_software",
		title: "Blog Generator *",
		filterable: true,
		width: "9%"
	}, {
		field:"notes",
		title: "Notes",
		filterable: true,
		width: "17%"
	}, { 
		command: ["destroy"], title: "&nbsp;", width: "7%" 
	}
	]// columns:

});// $("#feedsGrid").kendoGrid({

<div id="feedsGrid"></div>

Sever-Side Logic

Server-Side Logic Used to Initially Populate the Grid

The getDemoFeeds function, invoked by the Kendo dataSource read method, simply queries the database and invokes the CFJson component to convert and return the ColdFusion query object into JSON. The optional id and url arguments are not used in this demonstration.

<cffunction name="getDemoFeeds" access="remote" returnformat="json" hint="Returns all of the blog requests">
		
	<cfargument name="id" required="false" default="" />
	<cfargument name="url" required="false" default="" />

	<cfquery name="Data" datasource="#variables.cfbloggersDsn#">
		SELECT	
			id, 
			name, 
			description, 
			url, 
			rss_url, 
			blog_software, 
			site_image,
			notes,
			request_approved
		FROM	blog_request
		<cfif len(trim(arguments.id))>
			AND id = <cfqueryparam value="#arguments.id#" cfsqltype="cf_sql_integer" />
		<cfelseif len(trim(arguments.url))>
			AND	url = <cfqueryparam value="#arguments.url#" cfsqltype="cf_sql_varchar" />
		</cfif>
		ORDER BY name asc
	</cfquery>

	<!--- Convert the query object into JSON using the convertCfQuery2JsonStruct method --->
	<cfinvoke component="#application.cfJsonComponentPath#" method="convertCfQuery2JsonStruct" returnvariable="jsonString">
		<cfinvokeargument name="queryObj" value="#Data#">
		<cfinvokeargument name="includeTotal" value="true">	
	</cfinvoke>

	<cfreturn jsonString>

</cffunction>

Server-Side Logic to Update, Insert or Delete Database Records Based Upon Values Passed via the Grid

The saveBlogRequestViaGrid method, invoked by the create, update and destroy methods found in the Kendo DataSource, updates the database on the server depending upon the action and models arguments. This function is written in ColdFusion, however, I will try to break it down to make it understood and relevant for non-Coldfusion programmers.

The Action URL Argument

Since much of the logic will be reused for all of our database operations to insert, update and delete records, I am using the action argument, passed via the grid in the URL, to specify which action to take when updating records. Simply put, I will process the incoming JSON, which will be the same for all operations, and use the action parameter to determine how to process the records.

Important note: the delete method is suppressed in our demonstration as I don't want all of the records to be deleted.

Inspecting JSON Data from the Models URL Argument

When using an editable grid, Kendo passes the grid data using JSON like so:

models:[{"total":147,"demo_notes":"","description":"Jochem's tech exploits ","blogsoftware":"http://wordpress.org/?v=2.7","recentposts":false,"id":48,"rssurl":"http://jochem.vandieten.net/feed
","url":"http://jochem.vandieten.net
","name":""it could be bunnies""}] 

Server-Side Logic to Update Records in the Database

I don't want to get caught up in the details of the server-side logic as these articles are mainly focused on implementing Kendo on the client side, so I will keep this brief. Here are the general steps that I am using  on the server side:

1. ColdFusion will remove the models URL argument, decode the URL and deserialize the JSON, and then loop through the data to determine the values that were selected by the user.
2. After the data is converted into a native ColdFusion array of structures, we will loop through the native ColdFusion object, set the default values for safety, and then validate the data. In this particular example, we are using JSoup to sanitize the data. We will cover more validation techniques along with JSoup in future articles.
3. After the data is properly validated, we will perform database operations that are determined by the action URL variable that was sent in.

Server-Side Code

<cffunction name="saveBlogReqestViaGrid" access="remote" returnformat="json" output="false">
	<cfargument name="action" type="string" required="yes" hint="Either update or insert">
	<!--- Note: the incoming string arguments will be like so:
	models:[{"total":147,"demo_notes":"","description":"Jochem's tech exploits ","blogsoftware":"http://wordpress.org/?v=2.7","recentposts":false,"id":48,"rssurl":"http://jochem.vandieten.net/feed
","url":"http://jochem.vandieten.net
","name":""it could be bunnies""}] --->
	<cfargument name="models" type="string" required="yes">

	<!--- Remove the 'models' in the string ---> 
	<cfset thisStr = replaceNoCase(models, 'models=', '', 'one')>
	<!--- Decode the string and make it into an array --->
	<cfset thisStr = urlDecode(thisStr)>
	<!--- Use the desiarilze function to get at the underlying data. --->
	<cfset thisStruct = deserializeJson(thisStr, false)>
	<!--- Now that we have a clean array of structures, loop thru the array and get to the underlying values that were sent in the grid. ---> 
	<!--- Loop thru the struct. --->
	<cfloop array="#thisStruct#" index="i">
		<!--- Note: some of the variables may not come thru if they are empty. Use error catching here to catch and continue processing if there is an error.  --->
		<cfparam name="id" default="" type="any">
		<cfparam name="name" default="" type="any">
		<cfparam name="description" default="" type="any">
		<cfparam name="url" default="" type="any">
		<cfparam name="rss_url" default="" type="any">
		<cfparam name="site_image" default="" type="any">
		<cfparam name="blog_software" default="" type="any">
		<cfparam name="notes" default="" type="any">
		<cfparam name="request_approved" default="" type="any">

		<cftry>
			<cfset blogId = i['id']>
			<cfset blogName = i['name']>
			<cfset blogDesc = i['description']>
			<cfset blogUrl = i['url']>
			<cfset blogRssUrl = i['rss_url']>
			<cfset blogImage = i['site_image']>
			<cfset blogSoftware = i['blog_software']>
			<cfset notes = i['notes']>
			<cfset approved = i['request_approved']>
			<cfcatch type="any">
				<cfset error = "one of the variables was not defined.">
			</cfcatch>
		</cftry>

		<!--- Sanitize all of the incoming data using JSoup to prevent any tampering. I will cover JSoup in an upcoming article. --->
		<cfif len(blogName)>
			<!--- Sanitize the blog name --->
			<cfset blogName = JsoupObj.jsoupConvertHtmlToText(blogName)>
		</cfif>
		<cfif len(blogDesc)>
			<cfset blogDesc = JsoupObj.jsoupConvertHtmlToText(blogDesc)>
		</cfif>
		<!--- Test to see if this is a proper URL --->
		<cfif len(blogUrl) and isValid("URL",blogUrl)>
			<cfset blogUrl = blogUrl>
		<cfelse>
			<cfset blogUrl = "">
		</cfif>
		<cfif len(blogRssUrl) and isValid("URL",blogRssUrl)>
			<cfset blogRssUrl = blogRssUrl>
		<cfelse>
			<cfset blogRssUrl = "">
		</cfif>
		<cfif len(blogImage)>
			<cfset blogImage = JsoupObj.jsoupConvertHtmlToText(blogImage)>
		</cfif>
		<cfif len(blogSoftware)>
			<cfset blogSoftware = JsoupObj.jsoupConvertHtmlToText(blogSoftware)>
		</cfif>
		<cfif len(notes)>
			<cfset notes = JsoupObj.jsoupConvertHtmlToText(notes)>
		</cfif>

		<!--- Don't update the db unless the blog name came through properly (this should never be the case however) --->
		<cfif len(blogName)>

			<cfif action eq 'update'>
				<!--- Update the database. --->
				<cfquery name="updateBlogRequest" datasource="#variables.cfbloggersDsn#">
					UPDATE blog_request
					SET
					name = <cfqueryparam value="#blogName#" cfsqltype="cf_sql_varchar" />
					<cfif len(blogDesc)>
						,description = <cfqueryparam value="#blogDesc#" cfsqltype="cf_sql_varchar" />
					</cfif>
					<cfif len(blogUrl)>
						,url = <cfqueryparam value="#blogUrl#" cfsqltype="cf_sql_varchar" />
					</cfif>
					<cfif len(blogRssUrl) and isValid("URL",blogRssUrl)>
						,rss_url = <cfqueryparam value="#blogRssUrl#" cfsqltype="cf_sql_varchar" />
					</cfif>
					<cfif len(blogImage)>
						,site_image = <cfqueryparam value="#blogImage#" cfsqltype="cf_sql_varchar" />
					</cfif>
					<cfif len(blogSoftware)>
						,blog_software = <cfqueryparam value="#blogSoftware#" cfsqltype="cf_sql_varchar" />
					</cfif>
					<cfif len(notes)>
						,notes = <cfqueryparam value="#notes#" cfsqltype="cf_sql_varchar" />
					</cfif>
					WHERE id = <cfqueryparam value="#blogId#" cfsqltype="cf_sql_integer" />
				</cfquery>

			<cfelseif action eq 'insert'>

				<!--- Insert a new record into the database. --->
				<cfquery name="insertNewBlogRequest" datasource="#variables.cfbloggersDsn#">
					INSERT INTO blog_request (
						id,
						name,
						requestor_email
					<cfif len(blogDesc)>
						,description
					</cfif>
					<cfif len(blogUrl)>
						,url
					</cfif>
					<cfif len(blogRssUrl)>
						,rss_url
					</cfif>
					<cfif len(blogImage)>
						,site_image
					</cfif>
					<cfif len(blogSoftware)>
						,blog_software
					</cfif>
					<cfif len(notes)>
						,notes
					</cfif>
					) VALUES (
						<cfqueryparam value="#round(getLastBlogRequestId()+1)#" cfsqltype="cf_sql_integer" />
						,<cfqueryparam value="#blogName#" cfsqltype="cf_sql_varchar" />
						,<cfqueryparam value="" cfsqltype="cf_sql_varchar" />
					<cfif len(blogDesc)>
						,<cfqueryparam value="#blogDesc#" cfsqltype="cf_sql_varchar" />
					</cfif>
					<cfif len(blogUrl)>
						,<cfqueryparam value="#blogUrl#" cfsqltype="cf_sql_varchar" />
					</cfif>
					<cfif len(blogRssUrl)>
						,<cfqueryparam value="#blogRssUrl#" cfsqltype="cf_sql_varchar" />
					</cfif>
					<cfif len(blogImage)>
						,<cfqueryparam value="#blogImage#" cfsqltype="cf_sql_varchar" />
					</cfif>
					<cfif len(blogSoftware)>
						,<cfqueryparam value="#blogSoftware#" cfsqltype="cf_sql_varchar" />
					</cfif>
					<cfif len(notes)>
						,<cfqueryparam value="#notes#" cfsqltype="cf_sql_varchar" />
					</cfif>
					)
				</cfquery>
			</cfif><!---<cfif action eq 'update'>--->
		</cfif><!---<cfif len(blogName)>--->
	</cfloop>

	<cfset jsonString = []><!--- '{"data":null}', --->

	<cfreturn jsonString>
</cffunction>

<!--- CFBlog request helper functions --->
<cffunction name="getLastBlogRequestId" access="remote" returntype="numeric" output="false">
	<cfquery name="Data" datasource="#variables.cfbloggersDsn#">
		SELECT	
			Max(id) as max_id
		FROM	blog_request
	</cfquery>

	<cfreturn Data.max_id>

</cffunction>

In future articles, we will cover how to improve upon the out-of-the-box functionality of the grid that we implemented in this article.

Thanks for reading, and feel free to ask questions or provide your comments. 

The new version of CFBlogs ColdFusion Blog Aggregator has been released.

This version displays all of the blog posts in an attractive three-column card layout and displays the open graph image or a site image at the top of the post. The card images should allow the user to quickly convey the author of the post. Users can sort the grids by author by clicking on the card image.

This page also has several data grids in order to analyze ColdFusion blogging trends. I have put extra data available to the grids, such as including the generating blog software. Data from the grids and calendar widget on the bottom of the sidebar (opened by clicking on the hamburger) suggests that the current state of the ColdFusion blogging community is stronger than ever.

Advanced search capabilities are also present. Users can search from one or more active blog sites. There are nearly 150 ColdFusion-related blogs and all of the blogs have several years of data from which to search.  This should prove to be useful for ColdFusion developers wanting to research a particular ColdFusion-related topic.

This site should improve the SEO score of each blog covered as it provides a backlink to the blog postings. Google, and other search engines, consider backlinks 'votes' for a particular post and hopefully, this will improve the search scores for all the blogs covered. Additionally, there is also a ColdFusion community menu at the top of the page allowing users to quickly find other ColdFusion-related resources. 

CFBlogs also displays the posts from CFOverflow, and aggregates all of the posts to the CFBlogsFeed on Twitter, and the RSS feed can be used to show the ColdFusion blog posts on your own websites, instructions are found below.

The CFBlogs website can be found at https://www.cfblogs.org/

If you have any suggestions or want to add your own blog to the CfBlogs aggregator, please contact me.

How to put the CFBlogs feed on your own website

If you want to place the CFBlogs Feed on your own website, copy and paste the following code on your own site. An example of the following code can be found by clicking on the hamburger on this site.

<table align="center" class="k-content fixedPodTableWithWrap" width="100%" cellpadding="7" cellspacing="0">
	<cftry>
		<cfsilent>
		<cfset theURL = "https://gregoryalexander.com/cfblogs/rss.cfm">
		<cfhttp url="#theURL#" timeout="5">
		<cfset xml = xmlParse(cfhttp.filecontent)>
		<cfset items = xmlSearch(xml, "//*[local-name() = 'item']")>
		<!--- Set a loop counter to keep track of the current row for display purposes. --->
		<cfset feedLoopCount = 1>
		</cfsilent>
		<cfloop index="x" from="1" to="#min(arrayLen(items),5)#">
			<cfsilent>
			<cfset item = items[x]>
			<!-- Create alternating rows in the table. The Kendo classes which we will use are k-alt and k-content.
			We will create a border between the rows if the current row is not the first row. -->
			<cfif feedLoopCount mod 2>
				<cfset thisClass = 'k-content'>
			<cfelse>
				<cfset thisClass = 'k-alt'>
			</cfif>
			</cfsilent>
			<tr class="<cfoutput>#thisClass#</cfoutput>" height="35px;">
				<!--Create the nice borders after the first row.-->
				<cfif feedLoopCount eq 1>
				<td valign="top">
				<cfelse>
				<td align="left" valign="top" class="border">
				</cfif>
					<!--Display the content.-->
					<cfoutput>
					#item.comments.xmlText#<br/> 
					<a href="#item.link.xmlText#" <cfif darkTheme>style="color:whitesmoke"</cfif>>#item.title.xmlText#</a><br />
					</cfoutput>
				</td>
			</tr>
			<!---Increment the loop counter--->
			<cfset feedLoopCount = feedLoopCount + 1>
		</cfloop>
		<cfcatch>
			<tr>
				<td>
				<cfoutput>
				CFBloggers down
				</cfoutput>
				</td>
			</tr>
		</cfcatch>
	</cftry>
</table>
<br/>

The Kendo UI Grid is one of the most functional and elegant HTML5-based grid systems around. The Kendo UI Grid is used to easily allow users to visualize and interact with extremely large datasets- I have personally used Kendo Grids to convey over 60 million (60,00,000) records at a time using virtualization. The grids support paging, sorting, filtering, frozen columns, grouping, pivoting, etc, and allow for the editing of records. Grid data can also be exported to excel or pdf.

The grids are themeable and fully integrated with the other Kendo UI widgets and other Kendo UI widgets, such as Kendo dropdowns, can be embedded into a cell. The Kendo grids can be used natively with Angular, React, Vue and jQuery. Additionally, there are PHP and .Net wrappers, and Kendo UI can be easily used with ColdFusion as well. In this article we will show you how to use the grids with ColdFusion, however, like the rest of our articles, the client logic is written in JavaScript and jQuery and is server agnostic- you should be able to follow along.

Kendo Grid Demonstration

Please click on the button below to see the Kendo UI Grid that uses this code.

 Most Active ColdFusion Blogs

When Should You Use a Kendo UI Grid?

I use Kendo UI Grids every time I would typically use an HTML table to convey tabular data. The Kendo UI grids are interactive and offer a lot of improvements over a traditional HTML table, such as adding the ability to sort and group the data and will create a uniform look and feel when using a Kendo Theme. 

Kendo UI Grid Initializing and Binding Options

Kendo UI grids can be initialized using a simple HTML table or from a remote data service.

If the grids are initialized from a data service, the data can be bound to:

1. Local JavaScript Data
2. Remote Server Endpoint
3. Kinvey Backend Services
4. GraphQL Service
5. SignalR
6. WebSockets

In this series of articles, we will focus on binding the grids both locally and to a ColdFusion Service Endpoint.

CfBlogs Database Background

In the examples below, we will use ColdFusion to make a query to the cfblogs.org RSS blog aggregator database (formerly cfbloggers). The Cfblogs.org database collects data every 15 minutes from over 147 different ColdFusion blog sites and is updated whenever a new blog post is made and generates a tweet that summarizes the new blog post on Twitter.

Initializing a Grid from a Table

In the demonstration below, we will create a Kendo Grid from a static table showing the top ColdFusion-related blogs according to the number of posts made in the last calendar year.

In this example, we are querying the CfBlogs MySql database for active blogs, counting the number of blog posts in the last year, and getting the date of the last post. We are then looping through the query to create the data within the table cells. This code should be familiar to the ColdFusion developer.

SELECT	
		COUNT(e.posted) as count,
		MAX(date_format(e.posted, '%m/%d/%Y %r')) as maxDate,
		b.name as blog, 
		e.categories, 
		b.description as blogdescription, 
		b.url as blogurl,
		b.blogsoftware
	FROM	entries e, blogs b
	WHERE	e.blogidfk = b.id
	AND b.active = 1
	AND e.title is not null
	AND  e.posted > now() - INTERVAL 12 month
	GROUP BY blog
	ORDER BY count DESC
</cfquery>

<table id="grid">
	<colgroup>
		<col style="width:10%" />
		<col style="width:25%" />
		<col style="width:50%" />
		<col style="width:15%" />
	</colgroup>
	<thead>
		<tr>
			<th data-field="count"># Posts</th>
			<th data-field="blog">Blog</th>
			<th data-field="blogdescription">Description</th>
			<th data-field="maxDate">Last Post</th>
		</tr>
	</thead>
	<tbody>
	<cfoutput query="Data">
		<tr>
			<td>#count#</td>
			<td><a href="#blogurl#" target="new">#blog#</a></td>
			<td>#blogdescription#</td>
			<td>#maxDate#</td>
		</tr>
	</cfoutput>
	</tbody>
</table>

After generating the table, we simply initialize the Kendo UI Grid using a few lines of Javascript.

We are specifying the id of the table, grid, to initialize the grid. There are a few additional optional arguments that we will use to make this grid sortable.

The sortable argument makes the Kendo UI grid, well you guessed it- sortable, and the columnMenu argument places a menu at the top of the grid. The columMenu argument takes multiple additional arguments, and here we want to set filterable to false as we are binding the data to an HTML table.

These methods will be covered in more detail in future blog posts.

<script>
	$(document).ready(function() {
		$("#grid").kendoGrid({
		sortable: true,
		columnMenu: {
			filterable: false
		}
		});
	});
</script>

 Demonstration

Initializing a Kendo UI Grid Using a ColdFusion Remote Server Endpoint

Server Side Code Using ColdFusion

The following function is in the Demo.cfc ColdFusion Component. You don't need to use a ColdFusion component as the service endpoint, you can use any ColdFusion template, however, it is useful to use a component with multiple methods for a variety of reasons. Namely, ColdFusion components use an object-oriented approach, they are generally faster than a UDF, and they are generally more secure and extensible.

This function is no different than the server-side functions that we used for the Kendo dropdowns in previous articles. We are simply querying the database and transforming the ColdFusion query object into JSON using our CfJson method and returning the JSON string. You should note that we are also using returnFormat="json"  in the function declaration.

<cffunction name="getLastYearTopBlogsForGrid" access="remote" returnformat="json" output="false" 
		hint="Returns the most active ColdFusion blogs by most recent date for the last calendar year">
	<!--- There are no arguments for this function. --->
	<cfsetting enablecfoutputonly="true" />

	<cfset dsn = "cfbloggers">

	<cfquery name="Data" datasource="#dsn#">
		SELECT	
			COUNT(e.posted) as count,
			MAX(date_format(e.posted, '%m/%d/%Y %r')) as maxDate,
			b.name as blog, 
			e.categories, 
			b.description as blogdescription, 
			b.url as blogurl,
			b.blogsoftware
		FROM	entries e, blogs b
		WHERE	e.blogidfk = b.id
		AND b.active = 1
		AND e.title is not null
		AND  e.posted > now() - INTERVAL 12 month
		GROUP BY blog
		ORDER BY count DESC
	</cfquery>

	<!--- Using my jsonArray.cfc --->
	<!--- Convert the query object into JSON using the convertCfQuery2JsonStruct method --->
	<cfinvoke component="#jsonArray#" method="convertCfQuery2JsonStruct" returnvariable="jsonString">
		<cfinvokeargument name="queryObj" value="#Data#">
		<cfinvokeargument name="includeTotal" value="false">	
	</cfinvoke>

	<cfreturn jsonString>
</cffunction>

The JSON String Returned by the ColdFusion Endpoint

The ColdFusion server endpoint returns the following JSON. Note: I formatted the JSON and have only included the first 5 records for brevity.

[{
	"maxDate": "12/31/2021 01:46:00 AM",
	"total": 30,
	"blogsoftware": "http://wordpress.org/?v=2.9.2",
	"count": 206,
	"blogurl": "https://www.bennadel.com
",
	"id": 134,
	"blogdescription": "Ben Nadel's web development blog on ColdFusion, jQuery, HTML5, AJAX, SQL, and all aspects of web application development.",
	"blog": "Ben Nadel",
	"categories": "ColdFusion"
}, {
	"maxDate": "11/08/2021 10:51:00 PM",
	"total": 30,
	"blogsoftware": "FeedGenerator",
	"count": 124,
	"blogurl": "https://www.intothebox.org
",
	"id": 144,
	"blogdescription": "ContentBox",
	"blog": "ContentBox",
	"categories": "News, Schedule, Speakers"
}, {
	"maxDate": "12/17/2021 11:29:11 AM",
	"total": 30,
	"blogsoftware": "https://wordpress.org/?v=5.6.1",
	"count": 111,
	"blogurl": "https://coldfusion.adobe.com
",
	"id": 104,
	"blogdescription": "Connect with community",
	"blog": "ColdFusion",
	"categories": "Announcements,Blog,Online ColdFusion Meetup,announcements,blog,ColdFusion,online coldfusion meetup"
}, {
	"maxDate": "11/13/2021 06:00:00 PM",
	"total": 30,
	"blogsoftware": "Eleventy",
	"count": 77,
	"blogurl": "https://www.raymondcamden.com
",
	"id": 152,
	"blogdescription": "DevRel at large, Star Wars nerd, Web/Serverless hacker, lover of good beer and good books. Oh, and cats.",
	"blog": "Raymond Camden",
	"categories": "eleventy,static sites"
}, {
	"maxDate": "10/20/2022 04:45:00 PM",
	"total": 30,
	"blogsoftware": "Galaxie Blog",
	"count": 74,
	"blogurl": "https://www.gregoryalexander.com/blog/",
	"id": 1,
	"blogdescription": "A technical blog powered by Galaxie Blog - the most beautiful and functional open source ColdFusion/Kendo UI based blog in the world.",
	"blog": "Gregory's Blog",
	"categories": "Galaxie Blog"
}]

Inspect the JSON Yourself Using the Browsers Inspector

For debugging purposes, you often will want to inspect the JSON yourself using the browser's developer tools. 

All of the major browsers have some type of developer console to inspect the web page elements and browser traffic. If you're using Chrome, launch the DevTools console by pressing the F12 button, or if you're on a Mac, press the function and F12 key at the same time. 

Once the DevTools inspector is open, click on the network tab, and refresh the Kendo window and you should see a link to the Demo.cfc?method=topBlogsByPostsForCalendarYear in the list to the right. Click on it to see the JSON string returned from the server. For more information on the inspector, please refer to your browser's documentation.

The Kendo DataSource

The following Kendo DataSource invokes the topBlogsByPostsForCalendarYear function in the Demo.cfc ColdFusion component that we covered above. There is nothing different than the data source logic that we used in previous articles, however, in future Kendo Grid-related articles, we will identify the datatype inside the data source for advanced grid handling.

var topBlogsByPostsDs = new kendo.data.DataSource({
	// Determines which method and cfc to get and set data.
	transport: {
		read: {
			url: "<cfoutput>#application.baseUrl#</cfoutput>/demo/Demo.cfc?method=topBlogsByPostsForCalendarYear", // the cfc component which processes the query and returns a json string.
			dataType: "json", // Use json if the template is on the current server. If not, use jsonp for cross domain reads.
			method: "post" // Note: when the method is set to "get", the query will be cached by default. This is not ideal.
		}//read:
	},//transport:
	cache: false
});//topBlogsByPostsDs = new kendo.data.DataSource

Initializing the Kendo UI Grid

The script to initialize the grid inserts the grid widget into the grid div in the client-side code.

We are using the topBlogsByPostsDs data source and setting the basic grid options to allow sorting and allowing the user to search the grid for data using filterable: true. We will cover the column menu arguments in later articles.

Arguments in the columns array are optional, you can omit them, however, the grid will render all of the columns with equal widths and the column title will be the name of the database column which is not ideal.

The columns array should always be used with the Kendo UI grid in order to specify the column title, whether you want the column to have search filters, and to set the column widths. 

Here we are applying the column database name to the field, setting the title of the column, specifying whether the column filter menus are available, and set the column widths. The width argument can be a numeric value if you want to set a pixel width, or as a string, if you want to use percents.

var topBlogsByPosts = $("#grid").kendoGrid({
	dataSource: topBlogsByPostsDs,
	sortable: true,
    columnMenu: {
        filterable: false
    },
    // Column properties
    columns: [{
        field:"count",
        title: "# Posts",
        filterable: true,
        width:"15%"
    }, {
        field:"blog",
        title: "Blog",
        filterable: true,
        width:"20%"
    }, {
        field:"blogdescription",
        title: "Description",
        filterable: true,
        width:"50%"
    }, {
        field:"blogurl",
        title: "URL",
        filterable: true,
        width:"20%"
    }]// columns:
});// var topBlogsByPosts = $("#grid").kendoGrid

Client Side Code

The client-side code should be self-explanatory- the only thing of note here is that we are placing a div with the id of grid that is used to contain the Kendo grid.

<h2>Most active ColdFusion blogs in the last year</h2>
<p>Based upon the number of posts made within the last year according to <a href="www.cfblogs.org">CfBlogs.org</a></p>

<!--- Empty iv container for the grid. --->
<div id="grid"></div>

We will be covering more advanced Kendo UI Grid examples in future articles.

Thanks for reading!

Further Reading

• Kendo Grid Overview (Telerik)
• Kendo Grid API (Telerik)

As we previously mentioned, the Kendo MultiSelect widget offers significant enhancements to a traditional dropdown menu and can be used to replace a long list of checkboxes. In this article, we will take a deep dive into the Kendo MultiSelect, show how it can be prepopulated with existing values, and how to dynamically populate it using cascading dropdowns.

Like the rest of the posts in this series, we will be using ColdFusion on the server side, however, it should be easily understood if you use a different server-side language, and you should be able to follow along.

Visual Demonstration of Kendo's MultiSelect vs HTML MultiSelect

A picture is worth a thousand words. I am going to contrast the Kendo MultiSelect against traditional HTML checkboxes to visually convey the benefits of using the Kendo MultiSelect.

In the following interfaces, we are prepopulating the form with the US states on the Pacific seaboard selected.

Kendo MultiSelect

As you can see here, with the Kendo MultiSelect the selected values are front and center allowing the user to quickly see what is selected without forcing them to scroll down a long list of items. The Kendo MultiSelect also has search functionality to allow the user to quickly select additional values. The Kendo MultiSelect is also much more elegant and it takes up less space on the screen.

The Kendo MultiSelect's ability to put information front and center makes it a perfect tool to conceptualize related groups of information, however, in order to convey this we need to be able to dynamically populate this list.

Traditional HTML Multi-Select

The traditional multi-select requires you to scroll way down to see Oregon and Washington that are selected, and you better make sure not to accidentally click on one of the items while scrolling or the selection will be gone!

Dynamically Removing the Selected Kendo MultiSelect Options

To remove all of the selected values in the Kendo MultiSelect, simply pass an empty array to the MultiSelect value method like so:

$("#stateDropdown").kendoMultiSelect({
	placeholder: "Select...",
	autoBind: false,
	dataTextField: "name",
	dataValueField: "id",
	filter: "contains",
	dataSource: stateDs,
	value: []
}).data("kendoMultiSelect");

Populating a Kendo MultiSelect With Initial Values

Use the MultiSelect value method to populate the values of a Kendo MultiSelect.

You can either use an array with comma-separated values or an array of structures for the value.  This value must have the same value and datatype as the data element that is used to populate the dataValueField. If the value and the data type do not match a data element used to populate the dataValueField, the value will be ignored. We will illustrate this below.

All of these examples are valid:

// Displays United States
value: [{ name: "United States", id: 233 }] // Note: the name will be ignored. 
value: [{ id: 233}]
value: [233]
// Displays United States, United States Minor Outlining Areas
value: [233,234]
value: [{id:233},{id:234}]

However, these examples do not work. See comments in code:

[{ name: "United States" }] // United States does not match a data element in the dataValueField and will be ignored
"233,234,235"// Missing array (the square brackets)

Dynamically Populating a Kendo MultiSelect

Overview

To dynamically populate a Kendo MultiSelect, we need to inspect data using either AJAX or using the Kendo DataSource and prepare the data for the MultiSelect value method.

If you're using jQuery AJAX, and the data from the server is already a comma-separated string or an array of structures, you may be able to dump the data into the Kendo MultiSelects value method. Otherwise, you will have to prepare the string or array by looping through the data.

If you're inspecting data from a Kendo Datasource, we will use a similar approach that we would use to interrogate the data using jQuery Ajax- we will loop through the data triggered by a parent Kendo widget and populate the values array using the JavaScript push method and use the new array in the Kendo MultiSelect value method. 

In this article, we will focus on interrogating data from the Kendo DataSource.

Potential Use Cases

Unlike the traditional HTML MultiSelect, a Kendo MultiSelect can be prepopulated with values to allow the user to easily visualize and interact with related groups of data. I often populate the MultiSelect widget to allow the users to conceptualize related data with a predefined starting point.  

There are many other reasons to dynamically populate the MultiSelect. For example, we can clean up the selected values in a MultiSelect if the child values don't relate to other parent data. For example, in our previous Cascading MultiSelect article, we dynamically removed states from a child MultiSelect when the state's country was removed in the parent country MultiSelect menu. 

MultiSelect Dynamic Population Demonstration

The following example allows the user to select a world region that they are interested in exploring. Once the user selects a world region, the region states will be dynamically populated in the child state multi-select.

We will go over the details of this code later in this article.

Extracting Data from a Kendo DataSource

To extract the data from a Kendo DataSource, we need to use Kendo's data method on the Kendo DataSource. Unfortunately, we can't use this data to directly populate the MultiSelect's value method as the JSON extracted from the Kendo DataSource has been transformed into a specialized Kendo Observable Array JavaScript object. Instead, we need to loop through the data and create a string of values separated by commas using the JavaScript push method.

The populateCountry function below performs all of the necessary steps to extract the data from the countryDs data source and populates the country MultiSelect with values. This function is invoked using the change method on the parent subregion dropdown when the user selects a country. The full code is provided at the end of this article.

This function will use the data method on the countryDs Kendo DataSource that was consumed via the change function invoked when the user selects a subregion. Here, we don't need to use the Kendo fetch or read method as the data source already consumed the service endpoint when a region was selected. We will cover the fetch and read methods in future articles, but they don't apply here.

After using the Kendo DataSource's data method, we will create an empty countryIdList array to hold the list of values that we will later use in the MultiSelect's value method and loop through the data, which is a specialized JavaScript array.

Our loop will be a simple JavaScript for loop, and we will continue to loop through the records until there are no more records in the Kendo Observable array.

Inside this loop, we will extract the items that we need to populate the Kendo MultiSelect. In this example, we are getting the id, which is the primary key of the country table. Once the id has been extracted, we will use the JavaScript push method to push the value into the new countryIdList array that we just created.

After the loop has been completed and all of the ids have been saved to our new array, we will use this countryIdList to populate the MultiSelect using the widgets value method.

Here is the function:

The populateCountry function

// Populate the selected MultiSelect values from the datasource	
function populateCountries(e){
	// Get the data from the datasource
	var data = countryDs.data();
	// Create an array that we will use to populate the dropdown
	var countryIdList = [];
	// Loop through the data to create an array to send to the multi-select
	for (var i = 0; i < data.length; i++) {
		// Get the countryId
		var countryId = data[i].id;
		// Populate our new array with the value surrounded by qoutes
		countryIdList.push(countryId);
	}//..for (var i = 0; i < capabilityDsData.length; i++) {
	// At the end of the loop, opulate the multiSelect with the array that we just built
	countryDropdown.value(countryIdList);
}//..function...

 Get the Code