Entity Model Not Being Updated on SaveChanges

问题

I have a misunderstanding somewhere with the Entity Framework. This code is from my unit testing:

Public Sub UpdateRosterLinkTest()
    Dim target As PlayerAdmin = New PlayerAdmin()

    target.PlayerAdminManager = playerAdminTestManager
    target.Team = playerAdminTestManager.GetAirForceMensBB()

    playerAdminTestManager.resetRosterLink(target)
    Assert.IsNull(target.Team.RosterLink)

    Dim playerAdmin As PlayerAdmin = New PlayerAdmin()
    playerAdmin.TeamId = 12434
    playerAdmin.RosterLink = "Roster Link"

    playerAdmin.UpdateRosterLink()

    Dim team As DAL.Team = playerAdminTestManager.GetAirForceMensBB()
    Assert.AreEqual("Roster Link", team.RosterLink)

End Sub

I'm creating a PlayerAdmin, which is a model class. target.Team is an Entity object. What I do is reset the RosterLink field in the Team just to make sure our test starts out at the same place. Then I call the UpdateRosterLink() function. That looks like:

Function UpdateRosterLink() As Integer
        If (PlayerAdminManager Is Nothing) Then
            PlayerAdminManager = New PlayerAdminManager()
        End If

        Team = PlayerAdminManager.GetTeamByTeamId(TeamId)
        Team.RosterLink = RosterLink
        Dim numberOfChanges As Integer = PlayerAdminManager.SaveChanges()
        Return numberOfChanges
    End Function

When I run this code, I can see the changes saved to the SQL Server this pulls from (RosterLink = Roster Link, like I set in the unit test).

However, my unit test is failing, because team.RosterLink is still Nothing. The function GetAirForceMensBB() returns the Team with TeamId = 12434:

Function GetAirForceMensBB() As DAL.Team
    Return (From team In Container.Teams Where team.TeamId = 12434).SingleOrDefault
End Function

I'm sure I'm using the entity framework incorrectly and it probably has something to do with the fact that I am calling the PlayerAdminTestManager in different places, but I don't understand why. Although, I set the PlayerAdminManager to be the PlayerAdminTestManager. PlayerAdminTestManager extends PlayerAdminManager, fyi.

Why is team.RosterLink not showing the update from UpdateRosterLink?

Thanks

EDIT Container is my ObjectContext. This is how I access the information stored in the database. Container.Teams represents my Teams table.

回答1:

The problem was I was referencing different instantiations of the Container (each manager created its own). Thus, the entity items were not attached to anything.

Doh!

来源：https://stackoverflow.com/questions/8347491/entity-model-not-being-updated-on-savechanges