Create a Vue Front-End Application with a Document Viewer

• Jan 27, 2025
• 4 minutes to read

The Web Document Viewer is used in applications that contain client and server parts:

Client

A Web Document Viewer integrated in a client Vue application displays a report provided by the server-side model.

Server

The server is an ASP.NET Core application that handles client data requests and provides access to data sources, report storage, and other back-end capabilities.

This tutorial creates and configures a client React application and a server ASP.NET Core backend. The client contains the Web Document Viewer control.

View Example

Prerequisites

• Node.js v18.3 or later
• .NET 8 SDK or later

Note the following details about package versions:

• The script version on the client should match the library version on the server.
• DevExpress npm package versions should be identical.

Server (Back-End) Application

Use the DevExpress CLI Template

You can use DevExpress CLI Templates to create an ASP.NET Core back-end application. Begin with the steps below:

1. Install DevExpress ASP.NET Core project templates from nuget.org:

   .NET CLI

   dotnet new install DevExpress.AspNetCore.ProjectTemplates
   

2. Create a back-end Reporting application for a Document Viewer:

   dotnet new dx.aspnetcore.reporting.backend -n ServerApp --add-designer false
   

   You can use the following parameters to see available command options: -? | -h | --help.

3. Enable cross-origin requests (CORS). Specify the policy that allows any local application to access the report’s back-end. Use the SetIsOriginAllowed method to set it up.

   Call the UseCors method and pass the policy name as a parameter. The UseCors method should be called after the UseRouting method and before any MVC-related code. Place the UseCors method before the UseMvc or UseEndpoints methods.

   Open the application startup file and insert the following code:

   Program.cs

   var builder = WebApplication.CreateBuilder(args);
   
   builder.Services.AddCors(options => {
       options.AddPolicy("AllowCorsPolicy", builder => {
           // Allow all ports on local host.
           builder.SetIsOriginAllowed(origin => new Uri(origin).Host == "localhost");
           builder.AllowAnyHeader();
           builder.AllowAnyMethod();
       });
   });
   
   var app = builder.Build();
   
   app.UseRouting();
   app.UseCors("AllowCorsPolicy");
   
   app.UseEndpoints(endpoints => {
       endpoints.MapControllerRoute(
           name: "default",
           pattern: "{controller=Home}/{action=Index}/{id?}");
   });
   
   app.Run();
   

4. To run the server-side application, run the following command:

   cd ServerApp
   dotnet run
   

Use Visual Studio Template

To create a back-end application from a Microsoft or DevExpress Template in Visual Studio, review the following help topics:

• Document Viewer Server-Side Application (ASP.NET Core)
• Document Viewer’s Server-Side Configuration (ASP.NET MVC)

Client (Front-End) Application

2. Create a Vue application with the default preset:

   npm create vue@latest vue-document-viewer
   

3. Navigate to the project folder and install DevExpress npm packages:

   cd vue-document-viewer
   npm install devextreme@24.2-stable @devexpress/analytics-core@24.2-stable devexpress-reporting@24.2-stable
   

4. Create a src/App.vue file with the following content:

   App.vue

   <template>
     <div ref="viewer" style="position: absolute; left: 0; right: 0; top: 0; bottom: 0"></div>
   </template>
   <script>
     import 'devexpress-reporting/dx-webdocumentviewer';
     import {DxReportViewer} from 'devexpress-reporting/dx-webdocumentviewer';
     import * as ko from 'knockout';
   
     export default {
       name: "WebDocumentViewer",
       mounted() {
         const reportUrl = ko.observable("TestReport");
         const viewerRef = this.$refs.viewer;
         const requestOptions = {
           host: " http://localhost:5000/",
           invokeAction: "DXXRDV"
         };
         const viewer = new DxReportViewer(viewerRef, {
           reportUrl,
           requestOptions
         });
         viewer.render();
       },
       beforeUnmount() {
         ko.cleanNode(this.$refs.viewer);
       }
     };
   </script>
   

5. Add styles to the src/main.js file:

   main.js

   import "devextreme/dist/css/dx.light.css";
   import "@devexpress/analytics-core/dist/css/dx-analytics.common.css";
   import "@devexpress/analytics-core/dist/css/dx-analytics.light.css";
   import "devexpress-reporting/dist/css/dx-webdocumentviewer.css";
   import { createApp } from 'vue'
   import App from './App.vue'
   
   createApp(App).mount('#app')
   

6. Remove default project styles to avoid conflicts. To do this, remove the ./assets/main.css import in the main.js file.

Run the Project

1. Run the server application.

   Make sure to specify the correct server-side port (5000 in this example) and report name (TestReport in this example) in the Viewer.vue file.

2. Run the client application:

   npm run dev
   

3. Open your browser and navigate to the URL specified in the command output to see the result.

Troubleshooting

When you start the application, you may encounter the following issues:

Page is blank

The Document Viewer page is blank. The following error message is displayed at the bottom of the page:

Could not open report ‘TestReport’

Check the following:

• The backend application is up and running.
• The backend application runs on the port specified in the host setting of the Document Viewer component.
• The application’s URI is compliant with the CORS policy specified in your back-end application.
• The reportUrl setting value matches an existing report. For the backend application, ensure that either the Reports folder contains a reportUrl.repx file or the ReportsFactory.Reports dictionary contains the reportUrl entry (if the back-end application originated from the DevExpress template).
• The version of DevExpress npm packages should match the version of NuGet packages. Enable Development Mode to check for a library version mismatch on every request to the server. For details, review the following help topic: Server-Side Libraries Version.

Refer to the following topic for more information: Troubleshooting.