Database migrations with Entity Framework Core sample app

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This sample demonstrates how to use Entity Framework Core's migrations feature with Aspire.

The sample has three important projects:

  • DatabaseMigrations.ApiService - A web app that uses the database.
  • DatabaseMigrations.MigrationService - A background worker app that applies migrations when it starts up.
  • DatabaseMigrations.ApiModel - The EF Core context and entity types. This project is used by both the API and migration service.

DatabaseMigrations.ApiService and DatabaseMigrations.MigrationService reference a SQL Server resource. During local development the SQL Server resource is launched in a container.

Demonstrates

  • How to create migrations in an Aspire solution
  • How to apply migrations in an Aspire solution

Sample prerequisites

This sample is written in C# and targets .NET 8.0. It requires the .NET 8.0 SDK or later.

Create migration

The DatabaseMigrations.MigrationService project contains the EF Core migrations. The dotnet ef command-line tool can be used to create new migrations:

  1. Update the Entry entity in database context in MyDb1Context.cs. Add a Name property:

    public class Entry
{
    public Guid Id { get; set; } = Guid.NewGuid();
    public string? Name { get; set; }
}

  2. Open a command prompt in the DatabaseMigrations.MigrationService directory and run the EF Core migration tool to create a migration named MyNewMigration.

    dotnet ef migrations add MyNewMigration

    The preceding command:

    • Runs EF Core migration command-line tool in the DatabaseMigrations.MigrationService directory.
      • dotnet ef is run in this location because it will be used as the default target project for the new migration and the tool will run the startup code in Program.cs to find and configure the context to be used.
    • Creates the migration named MyNewMigration in the DatabaseMigrations.MigrationService project.

  3. View the new migration files in the DatabaseMigrations.ApiModel project.

Note

To remove the unapplied migration you need to run dotnet ef migrations remove --force. The --force switch tells the tool to avoid connecting to the database

Run the app

If using Visual Studio, open the solution file DatabaseMigrations.sln and launch/debug the DatabaseMigrations.AppHost project.

If using the .NET CLI, run dotnet run from the DatabaseContainers.AppHost directory.

When the app starts up, the DatabaseMigrations.MigrationService background worker runs migrations on the SQL Server container. The migration service:

  • Creates a database in the SQL Server container.
  • Creates the database schema.
  • Stops itself once the migration is complete.