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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
Posted by 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
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
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
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
231,269 Points
Steven Parker
Steven Parker
231,269 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
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
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.