Entity Framework Migrations - Enable AutoMigrations along with added migration

Question

I\'m utilizing Entity Framework 4.3 Migrations in my project. I would like to use Automatic migrations so that when I make modifications to my domain objects and my context cla

Answer 1

Same solution that Roger did but using an static constructor on the DbContext. Full code below.... this allow the initialization code to live on the class itself and is self-invoked at the first instantiation of the DataDbContext class.

public partial class DataDbContext : DbContext
{
    public DataDbContext()
        : base("name=DefaultConnection")
    {
    }

    static DataDbContext() // This is an enhancement to Roger's answer
    {
        Database.SetInitializer(new DataDbInitializer()); 

        var configuration = new DataDbConfiguration();
        var migrator = new DbMigrator(configuration);

        if (migrator.GetPendingMigrations().Any())
            migrator.Update();
    }

    // DbSet's
    public DbSet CountryRegion { get; set; }
    // bla bla bla.....

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Remove();
        modelBuilder.Conventions.Remove();
        modelBuilder.Conventions.Remove();

        Configuration.ProxyCreationEnabled = false;
        Configuration.LazyLoadingEnabled = false;
        //Configuration.ValidateOnSaveEnabled = false; 

        base.OnModelCreating(modelBuilder);

        modelBuilder.Configurations.AddFromAssembly(Assembly.GetExecutingAssembly()); // Discover and apply all EntityTypeConfiguration of this assembly, it will discover (*)
    }

}

internal sealed class DataDbInitializer : MigrateDatabaseToLatestVersion
{
}


internal sealed class DataDbConfiguration : DbMigrationsConfiguration
{
    public DataDbConfiguration()
    {
        AutomaticMigrationsEnabled = true;
        AutomaticMigrationDataLossAllowed = true;
    }

    protected override void Seed(DataDbContext context)
    {
        DataSeedInitializer.Seed(context); 
        base.Seed(context);
    }
}

internal static class DataSeedInitializer
{
    public static void Seed(DataDbContext context)
    {
        SeedCountryRegion.Seed(context);
        // bla bla bla.....

        context.SaveChanges();
    }
}

internal static class SeedCountryRegion
{
    public static void Seed(DataDbContext context)
    {
        context.CountryRegion.AddOrUpdate(countryRegion => countryRegion.Id,

            new CountryRegion { Id = "AF", Name = "Afghanistan" },
            new CountryRegion { Id = "AL", Name = "Albania" },
            // bla bla bla.....

            new CountryRegion { Id = "ZW", Name = "Zimbabwe" });

        context.SaveChanges();
    }
}

public class CountryRegionConfiguration : EntityTypeConfiguration // (*) Discovered by
{
    public CountryRegionConfiguration()
    {
        Property(e => e.Id)
            .IsRequired()
            .HasMaxLength(3);

        Property(e => e.Name)
            .IsRequired()
            .HasMaxLength(50);
    }
}

public partial class CountryRegion : IEntity
{
    // Primary key 
    public string Id { get; set; }

    public string Name { get; set; }

}

public abstract class Entity : IEntity
{
    //Primary key
    public abstract T Id { get; set; }
}

public interface IEntity
{
    T Id { get; set; }
}

We can see that the Seed method is running again and again.. We can avoid this by checking if a migration already exits, since one is applied automatically when the database is create.. then we can refactor the DataDbConfiguration as follows...

internal sealed class DataDbConfiguration : DbMigrationsConfiguration
{
    private readonly bool _isInitialized;

    public DataDbConfiguration()
    {
        AutomaticMigrationsEnabled = true;
        AutomaticMigrationDataLossAllowed = true;

        var migrator = new DbMigrator(this);

        _isInitialized = migrator.GetDatabaseMigrations().Any();
    }

    protected override void Seed(DataDbContext context)
    {
        InitializeDatabase(context);
    }

    public void InitializeDatabase(DataDbContext context)
    {

        if (!_isInitialized)
        {
            if (context.Database.Connection.ConnectionString.Contains("localdb"))
            {
                DataSeedInitializer.Seed(context); // Seed Initial Test Data
            }
            else
            {
                // Do Seed Initial Production Data here
            }

        }
        else
        {
            // Do any recurrent Seed here
        }
    }
}