i am working on a project in C# (.NET), and i want to make initial migration but i got a problem. i have tried so many solutions but still got error.

AppDBContext:

 protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            object value = modelBuilder.Entity<Actor_Movie>().HasKey(am => new
            {  
                am.ActorId,
                am.MovieId,
            }
            );

            modelBuilder.Entity<Actor_Movie>().HasOne(m => m.Movie).WithMany(am => am.Actors_Movies).HasForeignKey(m => m.MovieId);

            modelBuilder.Entity<Actor_Movie>().HasOne(m => m.Actor).WithMany(am => am.Actors_Movies).HasForeignKey(m => m.ActorId);

            base.OnModelCreating(modelBuilder);


        }

MovieCategory.cs:

namespace eTickets.Data.Enums;

public class MovieCategory
{

}

Error:

PM> add-migration initial
Build started...
Build succeeded.
System.InvalidOperationException: The entity type 'MovieCategory' requires a primary key to be defined. If you intended to use a keyless entity type, call 'HasNoKey' in 'OnModelCreating'. For more information on keyless entity types, see https://go.microsoft.com/fwlink/?linkid=2141943.
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelValidator.ValidateNonNullPrimaryKeys(IModel model, IDiagnosticsLogger`1 logger)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelValidator.Validate(IModel model, IDiagnosticsLogger`1 logger)

 Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
The entity type 'MovieCategory' requires a primary key to be defined. If you intended to use a keyless entity type, call 'HasNoKey' in 'OnModelCreating'. For more information on keyless entity types, see https://go.microsoft.com/fwlink/?linkid=2141943.

let me know what i am doing wrong.

CodePudding user response：

In Entity Framework, most entities have a unique identifier to reference them. The error messages Staates that your MovieCategory class lacks such an identifier. Either add an Id property to MovieCategory:

public class MovieCategory
{
  public int Id { get; set; }
}

If you intend to create a keyless entity, use the method described in the error message or mark the class with the Keyless attribute (from EF Core 5):

[Keyless]
public class MovieCategory
{
}

More information on keyless entities can be found here.