Data seeding is the process of populating a database with a set of initial data. It is usually performed when the database is first created. These data are usually static and will not change over time. Data seeding is usually used to fill in some basic data, such as users, roles, permissions, products, classifications, etc.

Universal interface design

public interface IDataSeedingProvider
{
    Task SeedingAsync(IServiceProvider serviceProvider);
}

Implement specific interface

public class DataSeedingProvider(UserManager<User> userManager) : IDataSeedingProvider
{
    public async Task SeedingAsync(IServiceProvider ServiceProvider)
    {
        var user = await userManager.FindByNameAsync("admin");

        if (user == null)
        {
            await userManager.CreateAsync(new User
            {
                UserName = "admin",
                Email = "admin@test.com"
            }, "admin");
        }
    }
}

Register in the container

builder.Services.AddTransient<IDataSeedingProvider, DataSeedingProvider>();

Automated execution of extensions

public static class DataSeedingExtensions
{
    public static IApplicationBuilder UseDataSeedingProviders(this IApplicationBuilder app)
    {
        using var serviceScope = app.ApplicationServices.CreateScope();

        var dataSeedingProviders = serviceScope.ServiceProvider.GetServices<IDataSeedingProvider>();

        foreach (IDataSeedingProvider dataSeedingProvider in dataSeedingProviders)
        {
            dataSeedingProvider.SeedingAsync(serviceScope.ServiceProvider).Wait();
        }

        return app;
    }
}

Automatic registration implementation

public static class DataSeedingExtensions
{
    public static IServiceCollection AddDataSeedingProviders(this IServiceCollection services, Assembly? assembly = null)
    {
        assembly ??= Assembly.GetCallingAssembly();

        var dataSeedProviders = assembly.ExportedTypes.Where(t => t.IsAssignableTo(typeof(IDataSeedingProvider)) && t.IsClass);

        dataSeedProviders.ToList().ForEach(t => services.AddTransient(typeof(IDataSeedingProvider), t));

        return services;
    }
}

Execution order problem

The execution order of automatically registered providers is uncertain. If you need to determine the execution order, you can design the Order attribute, and then order execution according to the Order attribute in the UseDataSeedingProviders method.

Used in microservices

builder.Services.AddDataSeedingProviders();
app.UseDataSeedingProviders();