Question

I would like to make a new, mapped entity that looks like this:

public class PathedItem
{
  public long Id { get; set; }      // from the Items table
  public string Name { get; set; }  // from the Items table
  public string Path { get; set; }  // from the Paths table
}

The problem is that Path is in a different table than the other items and one of those tables has a polymorphic foreign key. Here are my tables:

CREATE TABLE Items (
  [Id] [bigint] IDENTITY(1,1) NOT NULL,
  [Name] [nvarchar](255) NOT NULL)

CREATE TABLE Paths (
  [Id] [bigint] IDENTITY(1,1) NOT NULL,
  [Path] [nvarchar](255) NOT NULL,
  [ItemId] [bigint] NOT NULL,
  [ItemType] [int] NOT NULL)

Microsoft has HOWTOs on mapping entities to two tables (here and here), but they seem to rely on a normal foreign key.

Is there some way to map Paths.ItemId to Items.Id and then hardcode a value for Paths.ItemType in the join?

Answer 1

One way to do this would be to create a view, with the columns that you require and a filter on the ItemType.

Then add that view to your entity model.