Entity Framework Core: Include many-to-many related objects in WebAPI

Question

I\'m not too familiar with the .NET framework but decided to try out ASP.NET Core and EF Core. I want to make a pretty simple Web API backend but I\'m having trouble working

Answer 1

You have to change it as shown below.

Models :

namespace Test.Models
{
    public class Movie
    {
        public int MovieId { get; set; }
        public string Title { get; set; }
        public DateTime ReleaseDate { get; set; }
        public string Code { get; set; }
        public string Path { get; set; }

        public ICollection MovieActors { get; set; }
    }

    public class Actor
    {
        public int ActorId { get; set; }
        public string Name { get; set; }
        public ICollection MovieActors { get; set; }
    }

    public class MovieActor
    {
        public int MovieId { get; set; }
        public Movie Movie { get; set; }

        public int ActorId { get; set; }
        public Actor Actor { get; set; }
    }
}

Context :

protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);

        builder.Entity().HasKey(x => new { x.MovieId, x.ActorId});

        builder.Entity()
            .HasOne(m => m.Movie)
            .WithMany(ma => ma.MovieActors)
            .HasForeignKey(m => m.MovieId);

        builder.Entity()
            .HasOne(m => m.Actor)
            .WithMany(ma => ma.MovieActors)
            .HasForeignKey(a => a.ActorId);

    }

    public DbSet Movies { get; set; }

    public DbSet Actors { get; set; }

    public DbSet MovieActors { get; set; }

 }

You can navigate as shown below :

var actor = context.Actors
                   .Include(r => r.MovieActors)
                   .FirstOrDefault(a=>a.ActorId = 1)

var movies = actor.MovieActors.Select(c => c.Movie);

How to add a record :

var actor = new Actor { ... };
context.Actors.Add(actor);

var movie = new Movie { ... };
context.Movies.Add(movie);

var movieActor = new MovieActor { Actor = actor , Movie = movie };
context.MovieActors.Add(movieActor);

context.SaveChanges();