Question

I have a table in my db (a many to many table) that two classes A and B have created like this.

    this.HasMany(t => t.TrafficImageQuestions)
       .WithMany(t => t.TrafficImages)
        .Map(m =>
            {
                m.ToTable("TrafficImage_Answers");
                m.MapLeftKey("TrafficImagesGuid");
                m.MapRightKey("TrafficImageQuestionsId");


            });

Now i would like to assosiate my custom class to this same table “TrafficImage_Answers”, the class offcause have the left and right key and then also a 3. custom property.

(i did add the column to the database “Answer”)

    public class TrafficImageAnswer
    {
        public System.Guid TrafficImageGuid { get; set; }
        public int TrafficImageQuestionId { get; set; }
        public byte Answer { get; set; }
    }

I am doing this as i want entity model to keep track of my many to many relationship of A and B and still be able to look up the 3. property Answer that is in the database.

What i have tried

I tried to do the following:

    this.Property(t => t.TrafficImageQuestionId)
        .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);
    this.Property(t => t.TrafficImageGuid)
        .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

    // Table & Column Mappings
    this.ToTable("TrafficImage_Answers");

But i get that the table already exists, logic. I need to tell it that it just should use that table and not try to create it.
(im doing this with DB mitigrations in EF 5 and Package manager).

Answer 1

That is not supported. If you want to have additional field in the junction table for many-to-many relation you cannot map it as many-to-many any more. Each table can be mapped only once but mapping table to entity and to many-to-many relation in the same time makes it mapped twice.

You must change your TrafficImageQuestions and TrafficImages to use one to many relations with TrafficImageAnswer instead of many-to-many relation with each other.