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Create a Static Custom Item for the Web Dashboard

  • 6 minutes to read

Important

A custom item is an independent module called the extension. If you are not familiar with the basic concepts of extensions, please review the following topic before you continue: Extensions Overview.

This tutorial shows how to create a custom item that displays text and adds a custom property that allows you to change this static text in the UI.

StaticItemExample

You can download the ready-to-use projects:

View Example: ASP.NET Core Dashboard - Custom Item Tutorials

View Example: Dashboard for React - Custom Item Tutorials

Prerequisites

A custom item script depends on the platform you use:

Module script
Client components (Angular, React, Vue) use imports and classes to define a custom item.
Classic script
A script for the ASP.NET Web Forms, ASP.NET MVC, ASP.NET Core, BLazor, and JavaScript controls encapsulates a custom item in the IIFE function expression.

Before you begin, create a Web Dashboard project for the required platform.

Create an External Script

In your project, create an external HelloWorldItem.js file, so you can reuse the created extension in other Web Dashboard applications.

Define a Toolbox Icon

In the HelloWorldItem.js file, add a 24x24 SVG icon as a string variable:

var svgIcon = '<svg id="helloWorldItemIcon" viewBox="0 0 24 24"><path stroke="#42f48f" fill="#42f48f" d="M12 2 L2 22 L22 22 Z" /></svg>';

The icon will be used to display the custom item in the Toolbox.

Specify the Custom Item’s Settings

Implement the ICustomItemMetaData interface to define this custom item’s settings:

  • In the icon option, pass the SVG icon’s id (helloWorldItemIcon).
  • In the title option, specify the text displayed in the dashboard item caption and as the Toolbox element’s tooltip (Hello World Item).
var helloWorldItemMetaData = {
// ...
    icon: 'helloWorldItemIcon',
    title: 'Hello World Item'
};

As a result, the following icon is added to the Toolbox:

CustomItem_Static_Toolbox

Create a Custom Property

Use the ICustomItemMetaData.customProperties and ICustomItemMetaData.optionsPanelSections properties to define a custom option that allows a user to change the custom dashboard item’s display text:

web-dashboard-static-item-custom-property

import { CustomItem } from 'devexpress-dashboard/model'
// ...
var helloWorldItemMetaData = {
    customProperties: [{
        ownerType: CustomItem,
        propertyName: 'customProperty',
        valueType: 'string',
        defaultValue: 'Hello World!'
    }],
    optionsPanelSections: [{
        title: 'Custom Properties',
        items: [{
            dataField: 'customProperty',
            label: {
                text: 'Item Text'
            },
            editorType: 'dxTextBox',
            editorOptions: {
                placeholder: "Enter text to display"
            }
        }]
    }],
    // ...
};

Implement Custom Item Rendering

The CustomItemViewer class specifies visual representation of the custom item. Override the CustomItemViewer.renderContent method to display custom item content. Use the CustomItemViewer.getPropertyValue method to get the value of the created custom option and display this value in the viewer.

Note

Do not set IDs for DOM elements in the CustomItemViewer.renderContent method call. When the custom item is maximized, its viewer part (CustomItemViewer is copied with all its elements and the element ID will not be unique on the page.

import { CustomItemViewer, ResourceManager } from 'devexpress-dashboard/common'
// ...
class HelloWorldItemViewer extends CustomItemViewer {
    renderContent(element, changeExisting) {
        element.innerText = this.getPropertyValue('customProperty');
    };
}

Create an Extension

The ICustomItemExtension interface allows you to define a custom item as an extension. Use the ResourceManager.registerIcon static method to register the custom item’s icon. Pass the created metadata to the ICustomItemExtension.metaData property. Call the ICustomItemExtension.createViewerItem method to implement the created custom item.

import { CustomItemViewer, ResourceManager } from 'devexpress-dashboard/common'
// ...
class HelloWorldItem {
    constructor(dashboardControl) {
        ResourceManager.registerIcon(svgIcon);    
        this.name = "helloWorldItem";
        this.metaData = helloWorldItemMetaData;
    }

    createViewerItem(model, $element, content) {
        return new HelloWorldItemViewer(model, $element, content);
    }
}

export default HelloWorldItem;

Register the Custom Item Extension

Attach the created HelloWorldItem.js script file to the page containing the Web Dashboard code. The external script you created is now available in the application.

You need to register the extension before the control is rendered. Refer to the following topics for information on how to get access to the DashboardControl instance and customize it before any element in the Web Dashboard control has been rendered:

Register the created extension in the DashboardControl.registerExtension method call:

function onBeforeRender(e) { 
  var dashboardControl = e.component;
  dashboardControl.registerExtension(new DashboardPanelExtension(dashboardControl));
  dashboardControl.registerExtension(new HelloWorldItem(dashboardControl));
  // ...
}

Run the Project to See the Result

Run the project and click the Hello World Item Toolbox item to add the custom item to the dashboard:

CustomItem_Static_Toolbox

This action adds the custom item with the predefined ‘Hello World!’ text on its surface. Open the item’s Options menu and go to the Custom Properties section to change the displayed text:

StaticItemExample

In the next lesson, you will learn how to create a custom item that is bound to data, and how to display data from a data source.

Export Limitations

A custom item does not support the default export mechanism. For example, you cannot use WebDashboardExporter / ASPxDashboardExporter to export custom items. In this instance, you need to implement custom export: