Entity Framework Many to Many Database Migration - entity-framework

Question

I am building ASP MVC web site using Entity Framework 4.4 with .NET Framework 4.0
I've add to my model a many to many relation like so:
public class User {
public int UserID { get; set; }
public string Username { get; set; }
public virtual ICollection<Tenant> Tenants { get; set; }
}
public class Tenant {
public string TenantID { get; set; }
public string Name { get; set; }
public virtual ICollection<User> Users { get; set; }
}
When I run Add-Migration command I get this migration class (I remove the Down method)
public partial class TenantUsersManyToManyMigration : DbMigration
{
public override void Up()
{
CreateTable(
"dbo.UserTenants",
c => new
{
User_UserID = c.Int(nullable: false),
Tenant_TenantID = c.String(nullable: false, maxLength: 128),
})
.PrimaryKey(t => new { t.User_UserID, t.Tenant_TenantID })
.ForeignKey("dbo.Users", t => t.User_UserID, cascadeDelete: true)
.ForeignKey("dbo.Tenants", t => t.Tenant_TenantID, cascadeDelete: true)
.Index(t => t.User_UserID)
.Index(t => t.Tenant_TenantID);
}
}
Why are the field names for TenantID and UserID are User_UserID and Tenant_TenantID and not UserID and TenantID, respectively.
How can I change the default migration scaffolding (or my model) to make cascadeDelete to be false? (currently I simply change it by hand).

Answer 1

You can create your mapping table the way you're wanting using fluent notation. In your DbContext class, override the OnModelCreating with this:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<User>()
.HasMany(u => u.Tenants)
.WithMany(t => t.Users)
.Map(m =>
{
m.ToTable("UserTenants");
m.MapLeftKey("UserId");
m.MapRightKey("TenantId");
});
}
Also, using fluent, if you want to disable cascade deleting on individual tables, you can use the .WillCascadeDelete(false) when mapping properties. Here's a great post on MSDN on how to use fluent notations.

Answer 2

You can remove the cascade delete convention this way:
using System.Data.Entity.ModelConfiguration.Conventions;
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();
}
And then see if the scaffolding changes. I've personally never used it.
Also, Microsoft (kind of) explains the FK naming conventions in this link under the header Foreign Keys.