OnModelCreating Entity Framework Core

Question

This code is in MVC, I need to do something like this but in ASP.net Core, using Entity Framework Core, or with DataAnnotations (I've changed the parameter already from DbModelBuilder(MVC Entity Framework) to ModelBuilder(Entity Framework Core))

 protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>(); //error: Conventions is not recognized
            base.OnModelCreating(modelBuilder);
            modelBuilder.Entity<tbl_Line>()
                .HasMany(d => d.tbl_Policy)
                .WithRequired(c => c.tbl_Line) //error WithRequired not recognized
                .HasForeignKey(c => c.int_lineID);
        }

There are some errors when I'm trying to use it in Entity Framework Core:

1-'ModelBuilder' does not contain a definition for 'Conventions' and no extension method 'Conventions' accepting a first argument of type 'ModelBuilder' could be found (are you missing a using directive or an assembly reference?)

2-'CollectionNavigationBuilder<tbl_Line, tbl_Policy>' does not contain a definition for 'WithRequired' and no extension method 'WithRequired' accepting a first argument of type 'CollectionNavigationBuilder<tbl_Line, tbl_Policy>' could be found (are you missing a using directive or an assembly reference?)

Solution

Until there is support for ModelBuilder.Configurations I emulate the older Entity Framework construction with extension methods:

public static EntityTypeBuilder<Project> Map(this EntityTypeBuilder<Project> cfg)
{
    cfg.ToTable("sql_Projects");

    // Primary Key
    cfg.HasKey(p => p.Id);

    cfg.Property(p => p.Id)
        .IsRequired()
        .HasColumnName("ProjectId");

    return cfg;
}

and then call it from OnModelCreating like this...

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<Project>().Map();
    base.OnModelCreating(modelBuilder);
}

It is a bit clumsy, but cleaner, I think, than trying to configure dozens of entities within the main DbContext.

Comments

[Ivan Stoev]

A good starting point - EF Core vs. EF6.x

[Nathan McKaskle]

This method doesn't seem to exist.

[Neilski]

Which method are you referring to?