Seeding Data in ASP.NET Core with EF Core

What is Seeding?

Seeding provides a way to populate a database with initial data when the application starts. This is useful for default records, test data, or demo environments.

Define Seed Data

public class SeedData
{
    public static void Initialize(IServiceProvider serviceProvider)
    {
        using var context = new ApplicationDbContext(
            serviceProvider.GetRequiredService<DbContextOptions<ApplicationDbContext>>());

        if (context.Books.Any()) return;

        context.Books.AddRange(
            new Book { Title = "ASP.NET Core in Action", Author = "Andrew Lock", Price = 39.99M },
            new Book { Title = "Entity Framework Core Cookbook", Author = "Julie Lerman", Price = 44.99M }
        );

        context.SaveChanges();
    }
}

Register the Seeder

public class Program
{
    public static void Main(string[] args)
    {
        var host = CreateHostBuilder(args).Build();

        using (var scope = host.Services.CreateScope())
        {
            var services = scope.ServiceProvider;
            SeedData.Initialize(services);
        }

        host.Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder => { webBuilder.UseStartup<Startup>(); });
}

Running Migrations

Ensure the database schema matches the model before seeding:

dotnet ef migrations add InitialCreate
dotnet ef database update

Testing the Seed

Launch the app and navigate to /api/books (or any endpoint that returns the seeded entities). You should see the two books added above.