Question

I am trying to remove a reference to an Entity in a One-To-Many relationship in the following manner, but am receiving an error when I try to attach the object ‘o’ to my DbContext. The error is:

“Adding a relationship with an entity which is in the Deleted state is not allowed.”

I have also tried the following in place of setting the EntityState:

 _db.OrganizationMetrics.Remove(om)

What is the right way to remove this?

<HttpPost()>
Function Edit(ByVal ovm As OrganizationViewModel)

    Dim o As Organization


    o = AutoMapper.Mapper.Map(Of OrganizationViewModel, Organization)(ovm)

    For Each om In o.OrganizationMetrics
        _db.OrganizationMetrics.Attach(om)

        If om.Value = "removeMe" Then
            _db.Entry(om).State = EntityState.Deleted
        ElseIf om.Id = 0 Then
            _db.Entry(om).State = EntityState.Added
        Else
            _db.Entry(om).State = EntityState.Modified
        End If
    Next

    _db.Organizations.Attach(o) 'Error is thrown here

    If (ModelState.IsValid) Then

        _db.Entry(o).State = EntityState.Modified
        _db.SaveChanges()

        Return RedirectToAction("Index")
    Else

        Return View(ovm)
    End If

End Function

UPDATE:

This is my now functioning code. The key is to not map the children entities back to the parent entity model from the view model, so that I can deal with them individually.

    <HttpPost()>
    Function Edit(ByVal ovm As OrganizationViewModel)

        Dim o As Organization

        o = AutoMapper.Mapper.Map(Of OrganizationViewModel, Organization)(ovm) //The Automapper code ignores the OrganizationMetrics members
        _db.Organizations.Attach(o)

        For Each om In ovm.OrganizationMetrics
            _db.OrganizationMetrics.Attach(om)

            If om.Value = "removeMe" Then
                _db.Entry(om).State = EntityState.Deleted
            ElseIf om.Id = 0 Then
                _db.Entry(om).State = EntityState.Added
            Else
                _db.Entry(om).State = EntityState.Modified
            End If
        Next


        If (ModelState.IsValid) Then

            _db.Entry(o).State = EntityState.Modified
            _db.SaveChanges()

            Return RedirectToAction("Index")
        Else

            Return View(ovm)
        End If

    End Function

Answer 1

When you attach o with _db.Organizations.Attach(o), it goes through all its children and finds that some of them are deleted. When it tries to attach them, you get the error you’re showing. It makes perfect sense.

Step back and figure out what it is you want to do. The easiest way to delete something is to get it and then delete it. Something like:

context.DeleteObject(context.MyEntity.Single(r => r.Id == myId));

If you want, you can mock the MyEntity object with just its key and then delete that object, it will work as well and save you a select query.