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C# Entity Framework Basics Extending Our Entity Data Model Defining a Many-to-Many Relationship with an Explicit Bridge Entity

Joel Brennan
Joel Brennan
18,300 Points

An unhandled exception of type 'System.InvalidOperationException' occurred in EntityFramework.SqlServer.dll

ComicBook.cs:

namespace ComicBookGalleryModel.Models
{
    public class ComicBook
    {
        public ComicBook()
        {
            Artists = new List<ComicBookArtist>();
        }
        public int Id { get; set; }       
        public int IssueNumber { get; set; }
        public string Description { get; set; }
        public DateTime PublishedOn { get; set; }
        public decimal? AverageRating { get; set; }

        public Series Series { get; set; }
        public ICollection<ComicBookArtist> Artists { get; set; }

        public String displayText
        {
            get
            {
                return $"{Series?.Title} #{IssueNumber}";
            }
        }

        public void AddArtist(Artist artist, Role role)
        {
            Artists.Add(new ComicBookArtist()
            {
                Artist = artist,
                Role = role
            });
        }
    }
}
Joel Brennan
Joel Brennan
18,300 Points

ComicBookArtist.cs:

namespace ComicBookGalleryModel.Models
{
    public class ComicBookArtist
    {
        public int Id { get; set;  }
        public int ComicBookId { get; set; }
        public int ArtistId { get; set; }
        public int RoleId { get; set; }

        public ComicBook ComicBook { get; set; }
        public Artist Artist { get; set; }
        public Role Role { get; set; }
    }
}
Joel Brennan
Joel Brennan
18,300 Points

Artist.cs:

namespace ComicBookGalleryModel.Models
{
    public class Artist
    {
        public Artist()
        {
            ComicBooks = new List<ComicBookArtist>();
        }
        public int Id { get; set; }
        public string Name { get; set; }

        public ICollection<ComicBookArtist> ComicBooks { get; set; }
    }
}
Joel Brennan
Joel Brennan
18,300 Points

Program.cs:

namespace ComicBookGalleryModel
{
    class Program
    {
        static void Main(string[] args)
        {
            using (var context = new Context())
            {
                var series1 = new Series()
                {
                    Title = "The Amazing Spiderman"
                };
                var series2 = new Series()
                {
                    Title = "The Invicible Iron Man"
                };

                var artist1 = new Artist()
                {
                    Name = "Stan Lee"
                };
                var artist2 = new Artist()
                {
                    Name = "Steve Ditko"
                };
                var artist3 = new Artist()
                {
                    Name = "Jack Kirby"
                };

                var role1 = new Role()
                {
                    Name = "Script"
                };
                var role2 = new Role()
                {
                    Name = "Pencils"
                };
                var comicBook1 = new ComicBook()
                {
                    Series = series1,
                    IssueNumber = 1,
                    PublishedOn = DateTime.Today
                };
                comicBook1.AddArtist(artist3, role1);
                comicBook1.AddArtist(artist2, role2);

                var comicBook2 = new ComicBook()
                {
                    Series = series1,
                    IssueNumber = 2,
                    PublishedOn = DateTime.Today
                };
                comicBook2.AddArtist(artist1, role1);
                comicBook2.AddArtist(artist3, role2);

                var comicBook3 = new ComicBook()
                {
                    Series = series2,
                    IssueNumber = 1,
                    PublishedOn = DateTime.Today
                };
                comicBook3.AddArtist(artist1, role2);
                comicBook3.AddArtist(artist2, role2);


                context.ComicBooks.Add(comicBook1);
                context.ComicBooks.Add(comicBook2);
                context.ComicBooks.Add(comicBook3);

                context.SaveChanges();

                var comicBooks = context.ComicBooks
                    .Include(cb => cb.Series)
                    .Include(cb => cb.Artists.Select(a => a.Artist))
                    .Include(cb => cb.Artists.Select(a => a.Role))
                    .ToList();

                foreach (var comicBook in comicBooks)
                {
                    var artistRolesNames = comicBook.Artists
                        .Select(a => $"{a.Artist.Name} - {a.Role.Name}").ToList();
                    var artistRolesDisplayText = string.Join(", ", artistRolesNames);

                    Console.WriteLine(comicBook.displayText);
                    Console.WriteLine(artistRolesDisplayText);
                }

                Console.ReadLine();
            }
        }
    }
}
Steven Parker
Steven Parker
230,248 Points

If you run in Debug mode, you should be able to find out exactly where in the code this occurs.

2 Answers

Joel Brennan
Joel Brennan
18,300 Points

Hi Steven,

Additional information: A specified Include path is not valid. The EntityType 'ComicBookGalleryModel.ComicBookArtist' does not declare a navigation property with the name 'Role'.

Which is hit when it gets to this block: var comicBooks = context.ComicBooks .Include(cb => cb.Series) .Include(cb => cb.Artists.Select(a => a.Artist)) .Include(cb => cb.Artists.Select(a => a.Role)) .ToList();

I can't figure it out.

I thought I have the navigation property defined. Also the Roles.dbo doesn't seem to get generated.

Joel Brennan
Joel Brennan
18,300 Points

Found it! I had forgotten to add the public access modifier if Role.cs. Forgot to post my Role.cs Sorry. Thanks for the help.