Hi,

Referring to an EntitySet<T> property where T is a base class using InheritanceSchema.SingleTable throws an exception. The instances of T can be loaded directly (i.e. with LINQ) without issue. Is this a fault, or am I not supposed to use EntitySet<T> properties with base types like this?

(The exception is an ArgumentException with the following message: "Item with key '[ColumnBelongingToDerivedType]' was not found", where the value between square brackets is the column involved).

Sorry if that wasn't clear - I can post sample code if it will help.

Cheers,

Matt.

Edit: Gah, I'm not supposed to post my response as an answer, but a comment won't accommodate my response, so I'll just have to edit it and jam it here. Not my favourite support tool =/

Hi Alex,

Thanks for the quick response (and for tidying up my post). Yes, I'm using PairTo with the EntitySet.

So, my case is something like this:

public class MyItem : Entity {
   ...
   [Association(PairTo="Item")]
   public EntitySet<MyBase> Items { get; private set; }
}

public abstract class MyBase : Entity {
   ...
   [Field]
   public MyItem Item { get; set; }
}

public class MyDerivedString : MyBase {
   ...
   [Field]
   public string MyStringField { get; set; }
}

public class MyDerivedDateTime : MyBase {
   ...
   [Field]
   public DateTime MyDateTimeField { get; set; }
}

If I do something like this (assume all the appropriate constructors are in place):

MyItem foo = new MyItem();
MyDerivedString s = new MyDerivedString("Hello");
MyDerivedDateTime d = new MyDerivedDateTime(DateTime.Now);

then everything writes through to the database correctly.

If I then retrieve the records like this:

List<MyBase> fields = Query
   .All<MyBase>()
   .ToList();

then the list is loaded correctly, and I can iterate through the correctly loaded types and their respective properties (i.e. there is no "slicing").

However, if I simply load the item and attempt to access it like this:

Item myItem = Query
   .All<MyItem>()
   .FirstOrDefault();

foreach(MyBase b in myItem.Items) {
...
}

then I get the error I originally posted.

From your previous post it sounds like this is expected behaviour. If so, why is loading automatically through use of an EntitySet different from issuing a LINQ query using the base type?

Cheers,

Matt.