How to: Add a Dashboard Extension to an XAF ASP.NET Core Blazor Application

• Aug 29, 2023
• 3 minutes to read

You can use extensions to customize the dashboard control used by the Dashboards Module. This topic demonstrates how to integrate a simple example extension into your XAF ASP.NET Core Blazor application.

Step-by-Step Instructions

1. Copy the following dashboard extension files to the YourApplicationName.Blazor.Server\wwwroot folder:

   • BlazorDashboardApp\wwwroot\parameter-item.js. This file contains the definition of the ParameterCustomItem extension. You will create a Controller that loads this script in the last step.

     window.ParameterCustomItem = /*...*/;
     

   • BlazorDashboardApp\wwwroot\dashboard-events-scripts.js. This file contains the code that registers the extension in the dashboard control and adds custom toolbar buttons to Grid item captions:

     window.dashboardEvents = {
         onBeforeRender: (args) => {
             // Registers the Parameter item and the Dashboard Panel.
             var dashboardControl = args.component;
             dashboardControl.registerExtension(new ParameterCustomItem(dashboardControl));
             // ...
         },
         // Adds a new custom toolbar item to the dashboard item caption.
         extensions: {
             viewerApi: {
                 onItemCaptionToolbarUpdated: function (e) {
                     // ...
                 }
             }
         }    
     }
     

2. Create a new .js file in the YourApplicationName.Blazor.Server\wwwroot folder and call it xaf-dashboard-user-script. Copy the following code snippet to the file:

   const xafDashboardUserScript = {
       onBeforeRender: function (dashboardControl) {
           window.dashboardEvents.onBeforeRender({ component: dashboardControl });
           const viewerApi = dashboardControl.findExtension("viewerApi");
           viewerApi.on("itemCaptionToolbarUpdated",
               window.dashboardEvents.extensions.viewerApi.onItemCaptionToolbarUpdated);
       }
   };
   
   window.xafBlazorDashboardUserScripts = [xafDashboardUserScript];
   

   xafDashboardUserScript is a plain JavaScript object that contains a single onBeforeRender method. XAF calls this method before it renders a dashboard, because xafDashboardUserScript is included in the xafBlazorDashboardUserScripts array. The onBeforeRender method does the following:

   • It calls the window.dashboardEvents.onBeforeRender method.
   • It ensures that the onItemCaptionToolbarUpdated method is called. XAF does not support the extensions: { viewerApi: { ... } } syntax, therefore you must subscribe to the ViewerApiExtension‘s itemCaptionToolbarUpdated event explicitly.

3. To add custom scripts and the extension’s icons to the application, navigate to the YourApplicationName.Blazor.Server\Pages\_Host.cshtml file and link dashboard-events-scripts.js, xaf-dashboard-user-script.js, and the extension’s icons:

   <link href="_content/DevExpress.ExpressApp.Blazor/styles.css" rel="stylesheet" />
   <link href="css/site.css" rel="stylesheet" />
   <script src="dashboard-events-scripts.js"></script>
   <script src="xaf-dashboard-user-script.js"></script>
   @* Adds icons for a custom toolbar item: *@
   <div style="display: none;">
       <svg id="baseCircle" class="dx-dashboard-icon" style="fill: currentColor" viewBox="0 0 24 24" width="24" height="24"><circle cx="12" cy="12" r="11" /></svg>
       <svg id="greenCircle" class="dx-dashboard-green-icon" viewBox="0 0 24 24" width="48" height="48"><circle cx="12" cy="12" r="11" /></svg>
       <svg id="yellowCircle" class="dx-dashboard-yellow-icon" viewBox="0 0 24 24" width="48" height="48"><circle cx="12" cy="12" r="11" /></svg>
       <svg id="redCircle" class="dx-dashboard-red-icon" viewBox="0 0 24 24" width="48" height="48"><circle cx="12" cy="12" r="11" /></svg>
   </div>
   

4. To load the parameter-item.js file, that you downloaded in the first step of this instruction, navigate to the YourApplicationName.Blazor.Server\Controllers folder and create a new Controller. Name it AddDashboardCustomizationsController.cs and copy the following code snippet to the file:

   using DevExpress.DashboardBlazor;
   using DevExpress.ExpressApp;
   using DevExpress.ExpressApp.Dashboards.Blazor.Components;
   using DevExpress.Persistent.Base;
   using Microsoft.AspNetCore.Components;
   
   namespace YourApplicationName.Blazor.Server.Controllers;
   
   public class AddDashboardCustomizationsController : ObjectViewController<DetailView, IDashboardData> {
       protected override void OnActivated() {
           base.OnActivated();
           View.CustomizeViewItemControl<BlazorDashboardViewerViewItem>(this, CustomizeDashboardViewerViewItem);
       }
       void CustomizeDashboardViewerViewItem(BlazorDashboardViewerViewItem blazorDashboardViewerViewItem) {
           if (blazorDashboardViewerViewItem.Control is DxDashboardViewerAdapter dxDashboardViewerAdapter) {
               dxDashboardViewerAdapter.JSCustomizationModel.OnScriptsLoading =
                   EventCallback.Factory.Create<ScriptsLoadingEventArgs>(this, OnScriptsLoading);
           }
       }
       private void OnScriptsLoading(ScriptsLoadingEventArgs args) {
           args.Scripts.Add("./parameter-item.js");
       }
   }
   

   This way, XAF executes the parameter-item.js script only when it loads a dashboard (before it renders the dashboard control).

The Parameter custom item is now available in the Dashboard Designer, and you can see a custom toolbar item in the first Grid dashboard item.