EfCore 3.1 尝试添加已存在的列

Question

I have a working .NET Core 2.2 project, which I just upgraded to .NET Core 3.1

There is something weird with EntityFrameworkCore going on and I don't know where to start

I have the following (simplified) model:

public class Asset()
{
   [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
   [Key]
   public Guid Id { get; set; }
   public Guid MainImageId{ get; set; }
   public Image MainImage { get; set; }
   public ICollection<Image> Images { get; set; }
}

public class Image()
{
   [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
   [Key]
   public Guid Id { get; set; }
   public Guid AssetId { get; set; }
   public Asset Asset { get; set; }
}

So an Asset has 1 MainImage.

This is defined in my model like this:

modelBuilder.Entity<Image>().HasOne(x => x.Asset).WithMany(x => x.Images).OnDelete(DeleteBehavior.Restrict);

This definitely worked, until I upgraded. Now every time a SELECT happens on the Assets table, it is trying to select the column MainImageId1 , which doesn't exist. If I try to AddMigration I see that EF Core will add a column called MainImageId1 and put a foreign key in place to the Images table.

I have tried adding the right column name to this property, but this also did not work:

modelBuilder.Entity<Asset>().Property(x => x.MainImageId).HasColumnName("MainImageId");

Does anyone have any idea how I can debug this further? Is something wrong perhaps in my DbContext class?

Answer 1

I eventually found the answer. I was missing a property, which seems to be required to make sure Entity Framework understands the relationship.

public class Asset()
{
   [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
   [Key]
   public Guid Id { get; set; }
   public Guid MainImageId{ get; set; }
   public Image MainImage { get; set; }
   public ICollection<Image> Images { get; set; }
}

public class Image()
{
   [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
   [Key]
   public Guid Id { get; set; }
   public Guid AssetId { get; set; }
   public Asset Asset { get; set; }

   //THIS WAS ADDED TO SOLVE THE PROBLEM:
   public ICollection<Asset> MainAssets {get;set;}
}

I added the collection MainAssets to the Images class and then updated my model to include the following two mappings:

modelBuilder.Entity<Image>()
    .HasOne(x => x.Asset)
    .WithMany(x => x.Images)
    .HasForeignKey(x => x.AssetId);

modelBuilder.Entity<Asset>()
    .HasOne(x => x.MainImage)
    .WithMany(x => x.MainAssets)
    .HasForeignKey(x => x.MainImageId);

And now everything works fine again. It seems that by adding the collection of MainAssets was key to having Entity framework understand the relationship better.