EF trying to insert Unchanged entities

Question

Edit: GOT IT! Thanks for your help people :) I posted the "solution" at the end, altough I don't know if it'll help anyone, it was mostly due to bad design on my part..

I'm getting a DbUpdateException when trying to .SaveChanges()

An error occurred while saving entities that do not expose foreign key properties for their relationships. The EntityEntries property will return null because a single entity cannot be identified as the source of the exception. Handling of exceptions while saving can be made easier by exposing foreign key properties in your entity types. See the InnerException for details.

InnerException is:

Violation of PRIMARY KEY constraint « PK_ProduitDepot_1 » ... Cannot insert duplicate key in object Produit-Depot ..

Here's some code I use to see which entities should get saved:

 Dim allEntries = MyContext.ChangeTracker.Entries
    Dim unchangedEntities As New Dictionary(Of Object, EntityState)

    For Each entry As DbEntityEntry In allEntries
        Dim NotUnchangedEntity = entry.Entity
        If MyContext.Entry(NotUnchangedEntity).State <> EntityState.Unchanged Then
            unchangedEntities.Add(entry.Entity, MyContext.Entry(entry.Entity).State)
        End If
    Next

    MyContext.Database.Log = AddressOf Console.WriteLine
    context.SaveChanges()

I see in debugging mode that unchangedEntities is empty.

Is there something I'm missing about EF? I don't understand why there would be any SQL executed at all if there's only Unchanged entities in my context's cache...

The table Produit-Depot is a junction table with a * to * relation, so EF hasn't created a class for that table (It's a Database first project)

Let me know if there's anything unclear.

did you try this ? - https://stackoverflow.com/questions/7938384/an-error-occurred-while-saving-entities-that-do-not-expose-foreign-key-propertie — Mauricio Gracia Gutierrez, Apr 30 '18 at 13:32
I do have entities tracked by the context with datetime fields set to Nothing... but I'm able to save these entities no problem in many other scenarios. Am I supposed to set a date which doesn't make any sense in every field? :/ Amongst the 3 tables concerned by the error message (Produit, Depot and Produit-Depot), one table (Produit) has a datetime field and it always has a value — Pascal, Apr 30 '18 at 13:43
You won't see the implicit junction table entries in the `ChangeTracker.Entries` (there is a special relationship entry type not exposed by the `DbContext` API). — Ivan Stoev, Apr 30 '18 at 13:51
When you have a solution it is usual to answer you own question and accept it (it will by probably allowed after some time). That way other people will know that the question is answerd. — IvanH, Apr 30 '18 at 18:05

Pascal · Accepted Answer · 2018-05-01T14:57:35.467

Solution

Interesting part:

As Ivan Stoev pointed out, as the error message was about a junction table (which has no class associated to it, as EF didn't create any when generating my Model), those entitie weren't listed in the the ChangeTracker.Entries. That's why I believed all the entities were at Unchanged state.

Probably unhelpful part:

I solved my problem with an addition include, using Context.Person.Include("Cars.Wheels") (made up names, but you get the idea). I used to have only Context.MyEntity.Include("Cars") and somehow assign my Cars' Wheels navigation property manually later, using FK's.. This is where the issue came from.

EF trying to insert Unchanged entities

1 Answers1