How to: Use Multiple Data Models Connected to Different Databases in Entity Framework Core

Feb 21, 2026
4 minutes to read

This article describes how to implement an XAF application with custom Entity Framework DbContexts that work with separate databases. These modules do not depend on each other and thus can be reused in other applications independently.

View Example: How to connect different data models to several databases within a single application with Entity Framework Core

This example assumes that you have an XAF application that includes both Windows Forms and ASP.NET Core Blazor projects with standard authentication enabled and the Security System configured in Integrated Mode.

Define Separate Connection Strings

In configuration files for Blazor and WinForms projects, define three separate connection strings: one connection string for a database that stores security data, and two additional connection strings for separate databases used to store application data.

File: SolutionName.Blazor.Server/appsettings.json, SolutionName.Win/App.config

ASP.NET Core Blazor
Windows Forms

json

"ConnectionStrings": {
  "ConnectionString0": "Integrated Security=SSPI;Pooling=false;MultipleActiveResultSets=true;Data Source=(localdb)\\mssqllocaldb;Initial Catalog=DB0_EFCore",
  "ConnectionString1": "Integrated Security=SSPI;Pooling=false;MultipleActiveResultSets=true;Data Source=(localdb)\\mssqllocaldb;Initial Catalog=DB1_EFCore",
  "ConnectionString2": "Integrated Security=SSPI;Pooling=false;MultipleActiveResultSets=true;Data Source=(localdb)\\mssqllocaldb;Initial Catalog=DB2_EFCore",
}

xml

<connectionStrings>
  <add name="ConnectionString0" 
    connectionString="Integrated Security=SSPI;MultipleActiveResultSets=True;Data Source=(localdb)\mssqllocaldb;Initial Catalog=DB0_EFCore" 
    providerName="System.Data.SqlClient" />
  <add name="ConnectionString1" 
    connectionString="Integrated Security=SSPI;MultipleActiveResultSets=True;Data Source=(localdb)\mssqllocaldb;Initial Catalog=DB1_EFCore" 
    providerName="System.Data.SqlClient" />
  <add name="ConnectionString2" 
    connectionString="Integrated Security=SSPI;MultipleActiveResultSets=True;Data Source=(localdb)\mssqllocaldb;Initial Catalog=DB2_EFCore" 
    providerName="System.Data.SqlClient" />
</connectionStrings>

Configure the Main Module’s DbContext to Store Security Data

In the example project, the main module’s DbContext is configured to only store data used by the Security System (users, roles, and login information). The Template Kit generates the required code if you enable the Security System. Otherwise, you need to add required persistent classes and configure platform-specific projects as described in the following article: Use the Security System - Implement Standard Authentication in Code.

File: CommonModule/BusinessObjects/CommonModuleDbContext.cs

csharp

public class CommonModuleEFCoreDbContext : DbContext {
  // ...
  public DbSet<PermissionPolicyRole> Roles { get; set; }
  public DbSet<ApplicationUser> Users { get; set; }
  public DbSet<ApplicationUserLoginInfo> UserLoginInfos { get; set; }
  // ...
}

File: SolutionName.Blazor.Server/Startup.cs, SolutionName.Win/Startup.cs

ASP.NET Core Blazor
Windows Forms

csharp

public class Startup {
    // ...
    public void ConfigureServices(IServiceCollection services) {
        services.AddXaf(Configuration, builder => {
            builder.Security
                .UseIntegratedMode(options => {
                    options.RoleType = typeof(PermissionPolicyRole);
                    options.UserType = typeof(CommonModule.BusinessObjects.ApplicationUser);
                    options.UserLoginInfoType = typeof(CommonModule.BusinessObjects.ApplicationUserLoginInfo);
                })
            // ...
        });
    }
}

csharp

public class ApplicationBuilder : IDesignTimeApplicationFactory {
    public static WinApplication BuildApplication(string connectionString) {
        var builder = WinApplication.CreateBuilder();
        // ...
        builder.Security
            .UseIntegratedMode(options => {
                options.RoleType = typeof(PermissionPolicyRole);
                options.UserType = typeof(CommonModule.BusinessObjects.ApplicationUser);
                options.UserLoginInfoType = typeof(CommonModule.BusinessObjects.ApplicationUserLoginInfo);
            })
        // ...
}

Add Custom Modules to Store Data in Separate Databases

Use the Template Kit to add two new custom XAF modules to an XAF solution as described in the following article: Create a Custom XAF Module. For each custom module, implement its own DbContext and persistent classes.

Add static methods that configure the Object Space and DbContexts (SetupObjectSpace() and SetupDbContext()) to all module classes in the solution. Make sure that each module uses its own connection string.

File: ClassLibrary1/XafModule1.cs, ClassLibrary2/XafModule2.cs, CommonModule/Module.cs

csharp

using DevExpress.ExpressApp.ApplicationBuilder.Internal;
using Microsoft.Extensions.Configuration;

public class XafModule1 : ModuleBase {
    // ...
    // Specify a separate connection string for each module.
    const string ConnectionStringName = "ConnectionString1"; 

    public static void SetupObjectSpace<TContext>(IObjectSpaceProviderBuilder<TContext> objectSpaceProviderBuilder) 
        where TContext : IXafApplicationBuilder<TContext> {
        string connectionString = ConfigurationManager.ConnectionStrings[ConnectionStringName]?.ConnectionString;
        objectSpaceProviderBuilder.AddSecuredEFCore()
            .WithDbContext<ClassLibrary1EFCoreDbContext>((application, options) => {
                SetupDbContext(options, connectionString),
            }, ServiceLifetime.Transient);
    }

    public static void SetupObjectSpace<TContext>(IObjectSpaceProviderServiceBasedBuilder<TContext> 
      objectSpaceProviderBuilder, IConfiguration configuration) 
        where TContext : IXafApplicationBuilder<TContext>, IAccessor<IServiceCollection> {
        string connectionString = configuration.GetConnectionString(ConnectionStringName);
        objectSpaceProviderBuilder.AddSecuredEFCore()
            .WithDbContext<ClassLibrary1EFCoreDbContext>((application, options) => {
                SetupDbContext(options, connectionString),
            }, ServiceLifetime.Transient);
    }

    static void SetupDbContext(DbContextOptionsBuilder options, string connectionString) {
        ArgumentNullException.ThrowIfNull(connectionString);
        options.UseConnectionString(connectionString);
        options.UseObjectSpaceLinkProxies();
    }
}

Make the following edits to Startup.cs files in your Blazor and WinForms projects:

Register additional modules as shown in the following code snippet:
Call the SetupObjectSpace() static methods for the ClassLibrary1 and ClassLibrary2 modules. ASP.NET Core Blazor and Windows Forms projects require different overloads of this method: