Restore Data Connections in Blazor Report Viewer

• Feb 09, 2026
• 3 minutes to read

When you load reports from REPX files, the file may contain a connection string name. In this case, the Report Viewer attempts to create a connection string using this connection string name and retrieve data. You need to implement a service that resolves a connection name to a valid connection.

SQL Data Sources

To create this service for SQL data connections, implement the IConnectionProviderFactory service that creates the IConnectionProviderService service. The IConnectionProviderService service retrieves a connection string from the application configuration file and returns the string to the Report Viewer.

Follow the steps below:

1. Add a connection string to the appsettings.json file:

   appsettings.json

   "MyConnectionStrings": {
     "NWindConnectionString": "XpoProvider=SQLite;Data Source=|DataDirectory|/Data/nwind.db"
   }
   

2. Create the DataConnectionService.cs file in the Services folder with the following code that implements the services:

   Services/DataConnectionService.cs

   using DevExpress.DataAccess.Sql;
   using DevExpress.DataAccess.Web;
   using DevExpress.DataAccess.Wizard.Services;
   
   public class ReportDataConnectionProviderFactory : IConnectionProviderFactory {
       private readonly IConfiguration _configuration;
       public ReportDataConnectionProviderFactory(IConfiguration configuration) {
           this._configuration = configuration;
       }
       public IConnectionProviderService Create() {
           return new ReportDataConnectionProviderService(_configuration);
       }
   }
   
   public class ReportDataConnectionProviderService : IConnectionProviderService {
       private readonly IConfiguration _configuration;
       public ReportDataConnectionProviderService(IConfiguration configuration) {
           this._configuration = configuration;
       }
       public SqlDataConnection LoadConnection(string connectionName) {
           string localConnectionName = "DefaultConnection";
           return new SqlDataConnection {
               Name = connectionName,
               ConnectionString = _configuration.GetConnectionString(localConnectionName)
           };
       }
   }
   

   The service returns the DefaultConnection connection string for any data connection to which a report is bound.

3. Register the IConnectionProviderFactory and IConnectionProviderService services at application startup:

   Program.cs

   using DevExpress.DataAccess.Wizard.Services;
   // ...
   builder.Services.AddScoped<IConnectionProviderFactory, ReportDataConnectionProviderFactory>();
   builder.Services.AddScoped<IConnectionProviderService, ReportDataConnectionProviderService>();
   

JSON Data Sources

To create such a service for JSON data connections, implement the IJsonDataConnectionProviderFactory service that creates the IJsonDataConnectionProviderService service. The IConnectionProviderService service retrieves a connection string from the application configuration file and returns the string to the Report Viewer.

Follow the steps below:

1. Add a connection string to the appsettings.json file:

   appsettings.json

   "MyConnectionStrings": {
       "JsonConnection": "Uri=Data/nwind.json"
   }
   

2. Create the DataConnectionService.cs file in the Services folder with the following code that implements the services:

   Services/DataConnectionService.cs

   using DevExpress.DataAccess.Json;
   using DevExpress.DataAccess.Web;
   
   public class CustomJsonConnectionProviderFactory : IJsonDataConnectionProviderFactory
   {
       readonly IJsonDataConnectionProviderService connectionProviderService;
       public CustomJsonConnectionProviderFactory(IJsonDataConnectionProviderService connectionProviderService)
       {
           this.connectionProviderService = connectionProviderService;
       }
       public IJsonDataConnectionProviderService Create()
       {
           return connectionProviderService;
       }
   }
   
   public class CustomJsonConnectionProviderService : IJsonDataConnectionProviderService
   {
       readonly IConfiguration configuration;
   
       public CustomJsonConnectionProviderService(IConfiguration configuration)
       {
           this.configuration = configuration;
       }
   
       JsonDataConnection IJsonDataConnectionProviderService.GetJsonDataConnection(string name)
       {
           var customConnectionStrings =
              configuration
              .GetSection("MyCustomConnectionStrings")
              .AsEnumerable(true)
              .ToDictionary(x => x.Key, x => x.Value);
           if (!customConnectionStrings.ContainsKey(name))
           {
               throw new KeyNotFoundException($"Connection string '{name}' was not found.");
           }
           return new JsonDataConnection(customConnectionStrings[name]);
       }
   }
   

3. Register the IConnectionProviderFactory and IConnectionProviderService services at application startup:

   Program.cs

   using DevExpress.DataAccess.Wizard.Services;
   // ...
   
   builder.Services.AddScoped<IJsonDataConnectionProviderService, CustomJsonConnectionProviderService>();
   builder.Services.AddScoped<IJsonDataConnectionProviderFactory, CustomJsonConnectionProviderFactory>();