Update Database Connections (Web Forms)

• Aug 18, 2023
• 3 minutes to read

Runtime Update

You may need to update the database connections at runtime in the following situations:

• When connection strings depend on parameters determined at runtime (current user ID or location).
• When connection strings specified in the Configuration Manager (appsettings.json) should be filtered or replaced at runtime.

Resolve Connection by Name

When you create a data source with the Data Source Wizard, the Wizard creates a connection string in the application configuration file and specifies the connection name in the SqlDataSource.ConnectionName property. The saved report layout (.REPX file) contains only the connection name. When the report layout is loaded, the connection name is resolved to a connection string, and you can implement a custom resolution service (IConnectionProviderService), as described later.

Connection Serialized with Parameters

You cannot use the custom IConnectionProviderService if a serialized connection contains connection parameters. The IConnectionProviderService.LoadConnection method is not called when a report loads a layout that contains data source connections with embedded parameters.

If you have a saved report with serialized connection parameters, open the report, clear connection parameters, and save the report. The following code snippet uses the DataSourceManager to clear connection parameters:

• C#

XtraReport report;
var dataSources = DataSourceManager.GetDataSources(report, true);
foreach (var dataSource in dataSources) { 
   if(dataSource is SqlDataSource sds && !String.IsNullOrEmpty(sds.ConnectionName)) {
        sds.ConnectionParameters = null;
    }
}

Another option is the SqlDataSource.ConfigureDataConnection event. Handle the ConfigureDataConnection event and use the e.ConnectionParameters property to access and modify connection parameters. You can register the WebDocumentViewerOperationLogger service and subscribe to that event in the WebDocumentViewerOperationLogger.ReportOpening method.

How to Implement a Custom Connection Resolution Service

1. Implement the IConnectionProviderFactory service:

2. Implement the IConnectionProviderService class:

How to Register a Service

Register the MyConnectionProviderFactory service at application startup before the ASPxWebDocumentViewer.StaticInitialize method:

• C#
• VB.NET

protected void Application_Start() {
    // ...
    DevExpress.XtraReports.Web.WebDocumentViewer.DefaultWebDocumentViewerContainer.RegisterConnectionProviderFactory<MyConnectionProviderFactory>();
    //...
    DevExpress.XtraReports.Web.ASPxWebDocumentViewer.StaticInitialize();
    // ...
}

Protected Sub Application_Start()
    ' ...
    DevExpress.XtraReports.Web.WebDocumentViewer.DefaultWebDocumentViewerContainer.RegisterConnectionProviderFactory(Of MyConnectionProviderFactory)()
    ' ...
    DevExpress.XtraReports.Web.ASPxWebDocumentViewer.StaticInitialize()
    ' ...
End Sub