Question

I have been struggling with getting a field value change to commit. Is there something obviously wrong here:

<HttpPost()>
Function Details(id As Guid?, model As RosterDetailModel) As ActionResult
If model.Action = RosterDetailModel.ActionOption.Save Then
    If model.Action = RosterDetailModel.ActionOption.Save Then
        Dim invalid = False ' initalize able to save
        'check validations
        Dim sFirstname = IIf(model.NameFirst Is Nothing, String.Empty, model.NameFirst).ToString().Trim()
        If sFirstname = String.Empty Then
            invalid = True
            ModelState.AddModelError("NameFirst", "First Name is required.")
        End If

        If invalid = False Then
            'save is ok to do
            Using db As New BCData()
                Dim userModel As New RosterDetailModel(db, id)
                'Dim userModel As New RosterDetailModel
                'userModel =
                userModel.NameFirst = sFirstname
                'db.ApplyCurrentValues(userModel)
                'db.AcceptAllChanges()
                db.SaveChanges()
                'userModel.SaveChanges(db, id, userModel)
            End Using
        End If
    End If
End If
Return View(model)
End Function

I see Entity Model Not Being Updated on SaveChanges has “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.” .. im not sure what exactly i need to change. When i tried to do a Linq query and set values directly it would tell me the field is readonly.

If invalid = False Then
    'save is ok to do
    Using db As New BCData()
    'Dim userModel As New RosterDetailModel(db, id)
    Dim userModel = From studentusers In db.studentusers _
    Where _
      studentusers.studentGuid = id _
    Select _
      studentusers.cellPhone, _
      studentusers.officePhone, _
      studentusers.phone, _
      studentusers.alternateEmail, _
      studentusers.country, _
      studentusers.zip, _
      studentusers.state, _
      studentusers.city, _
      studentusers.address2, _
      studentusers.address1, _
      studentusers.ForumeMailNotificationPreferences, _
      studentusers.magazineSubscribed, _
      studentusers.avatar, _
      studentusers.dateStudentActivated, _
      studentusers.dateDownloadOn, _
      studentusers.dateInstructorOn, _
      studentusers.instructor, _
      studentusers.ctcAdmin, _
      studentusers.download, _
      studentusers.accessLevel, _
      studentusers.datecreated, _
      studentusers.guidsignaturecookie, _
      studentusers.password, _
      studentusers.organization, _
      studentusers.email, _
      studentusers.lastname, _
      studentusers.firstname, _
      studentusers.groupGuid, _
      studentusers.studentGuid


    db.Attach(userModel)
    'Dim userModel As New RosterDetailModel
    'userModel =
    userModel.FirstOrDefault.firstname = sFirstname '**<- **** READ ONLY ???**  
                'db.ApplyCurrentValues(userModel)
    'db.AcceptAllChanges()

    db.SaveChanges()
    'userModel.SaveChanges(db, id, userModel)
End Using

Answer 1

Reload the userModel from the database:

If invalid = False Then
    Using db As New BlueCardData()
        Dim userModel = (From studentuser In db.studentusers _
                         Where studentuser.studentGuid = id _
                         Select studentuser).Single()
        'original userModel from DB is attached to context now
        'change tracking will start from here

        userModel.firstname = sFirstname

        db.SaveChanges()
        'EF detects change of firstname and will create UPDATE statement
    End Using

Your second code doesn’t work because you are projecting into an anonymous type and you cannot change properties of anonymous types. They are always readonly.