Multiple children to parent viewmodel binding

Question

I am using entity type configuration to map to a DB that I cannot control. My parent object is a "user" based object which  has multiple one to many children entities to describe what each user is doing. The base model looks like this:

Imports System.ComponentModel.DataAnnotations
Imports System.Collections.ObjectModel
Public Class MappingRecord
    Implements IValidatableObject
#Region "properties"
    Public Property AppUserID() As String
    Public Property ReliefID() As Int32
    Public Overridable Property Clients() As ObservableCollection(Of ClientMapping)
    Public Overridable Property ServiceLines() As ObservableCollection(Of ServiceLineMapping)
    Public Overridable Property Capabilities() As ObservableCollection(Of CapabilityMapping)
    Public Overridable Property Assignments() As ObservableCollection(Of AssignmentMapping)
#End Region
' ---- cut
End Class

To read from the DB I created a repository object that can read all the records for a user at once and load this model object.

    Public Function GetUserMappingRecord(userid As String) As MappingRecord Implements IMappingRepository.GetUserMappingRecord
        Dim results = From x In _context.MappingRecordList.Include("ServiceLines") _
                .Include("Capabilities") _
                .Include("Clients") _
                .Include("Assignments")
        Where (x.AppUserID = userid)
        Select x
        Return results.FirstOrDefault
    End Function

This works fine but to better manage all the validation for the children records I have started to switch from just referencing an observable collection of each child object found in the base model (Clients, ServiceLines, Capabilities, Assignments), to a viewmodel for every "row" I would see in a view. The validation isn't overy complex but it lends itself to this approach. For example, each client (or service line, or capability, or assignment) record has an allocation value that can be 0-100, and the collection of those must total 100. The viewmodel for each child (client) and then for the collection of the children (client_collection) works well and does what I want.

My issue is trying to use my existing model to load my new view models. My main viewmodel reads the data from the repository via the MappingRecord object which has the observable collection for the children records. I used to bind datagrids to each of those observable collections but now I want to load them into new viewmodels (ClientMappingViewModel) that are collections of viewmodels (ClientMappingCollectionViewModel). I can load the records from my parent MappingRecord object by doing something like this

Public Property UserMappingRecord As MappingRecord
Public Property ClientMappingList As ClientMappingCollectionViewModel
ClientMappingList = New ClientMappingCollectionViewModel(_mappingRepository, UserMappingRecord.Clients)

But this doesn't provide a link to the original UserMappingRecord.Clients from the repository/context. So records that are added to the datagrid are not found in the MappingRecord and will not be subject to changes I've made to IValidatableObject.Validate.

The easy solution is to not load the MappingRecord object and instead load each collection of children separately but then I lose any work done with Validate logic. I think I'm missing something basic but I'm just not seeing it right now. I want the view to reference the new viewmodels I've created like ClientMappingCollectionViewModel but I also want to use the MappingRecord model to load the data into the new viewmodels so that I can get the validation logic built into both.

Answer 1

To put this another way which might add more clarity, my datagrid binding handles updates to existing records but not adds and deletes. Here is a quick code sample showing snips of the relevant code.

'top level viewmodel bound to view
Public Class MappingRecordViewModel
    'collection of client mapping view models
    Public Property ClientMappingList As ClientMappingCollectionViewModel
    'load mapping record from repository
    UserMappingRecord = _mappingRepository.GetUserMappingRecord(SelectedUser.ID)
    'load viewmodel collection with data from previous result
    ClientMappingList = New ClientMappingCollectionViewModel(_mappingRepository, UserMappingRecord.Clients)
Public Class MappingRecord
    'client mapping records in the MappingRecordClass
    Public Overridable Property Clients() As ObservableCollection(Of ClientMapping)
Public Class ClientMappingViewModel
    'client mapping view model
    Public Property ClientMappingRecord As ClientMapping
Public Class ClientMappingCollectionViewModel
    'collection of client mapping view models
    Public Property ClientMappingCollection As ObservableCollection(Of ClientMappingViewModel)

On the view the datagrid is bound to ClientMappingList.

I am not sure why updates to a row in the datagrid are reflected in both UserMappingRecord.Clients and ClientMappingList, yet adds and deletes are not. I think this is the root issue that I need clarity on.

Answer 2

Hi Pretzelb,

it is hard to find the root cause of your issue, could you code a samll sample with me to demonstrate "adds and deletes" issue, and then I will do my best to help you resolve it.

Best regards,

---

Sheldon _Xiao[MSFT]
MSDN Community Support | Feedback to us
Microsoft
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

Answer 3

I was afraid I had included too much code. Can you guide me on what else you might need?

I did manage to get a sample working against an EDMX Northwind model. This uses objectcontext instead of dbcontext but shows similar behavior. Updating order_detail records on the grid will save to the DB but new rows or deleted rows are not registered.

This is going to be a lot of code. I will try to limit it without causing confusion.

Imports NorthwindData
Class Application
    Private Sub Application_Startup(sender As Object, e As System.Windows.StartupEventArgs) Handles Me.Startup
        Dim view As New MainView
        Dim db As New NorthwindContext
        Dim rep As New NorthwindRepository(db)
        Dim vm As New MainViewModel(rep)
        view.DataContext = vm
        view.Show()
    End Sub
End Class

<Window x:Class="MainView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainView" Height="432" Width="728">
    <Window.Resources>
        <CollectionViewSource x:Key="cvsOrders" Source="{Binding Path=OrderCollectionVM.OrderVM_List}"/>
    </Window.Resources>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="60" />
            <RowDefinition Height="300*" />
            <RowDefinition Height="300*" />
            <RowDefinition Height="60" />
        </Grid.RowDefinitions>
        <StackPanel Grid.Row="0" Margin="5,0,0,0" FlowDirection="LeftToRight" Orientation="Horizontal" VerticalAlignment="Top"  HorizontalAlignment="Left" >
            <TextBlock Text="Select an order" Margin="5"></TextBlock>
            <ComboBox Height="28" Name="cmb1" Width="325" Margin="3"
                        IsEditable="False"
                        ItemsSource="{Binding Path=OrderCollectionVM.OrderVM_List,  Mode=OneWay,  UpdateSourceTrigger=PropertyChanged}"
                        SelectedItem="{Binding MySelectedOrder}">
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal" >
                            <TextBlock Text="{Binding Path=CustomerID}" />
                            <TextBlock Text=" " />
                            <TextBlock Text="{Binding Path=ShipName}" />
                            <TextBlock Text=" " />
                            <TextBlock Text=" (" />
                            <TextBlock Text="{Binding Path=OrderID}" />
                            <TextBlock Text=") " />
                        </StackPanel>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ComboBox>
            <Button x:Name="btnSaveAll" 
                    Content="Save" 
                    Margin="30,5,5,5" 
                    Command="{Binding  SaveRecordCommand}" 
                    />
        </StackPanel>
        
        <StackPanel Grid.Row="1" Margin="5,0,0,0" FlowDirection="LeftToRight" Orientation="Horizontal" VerticalAlignment="Top"  HorizontalAlignment="Left" >
            <TextBlock Text="Product List" Margin="5"></TextBlock>
            <DataGrid x:Name="grd1" AutoGenerateColumns="False"                           
                            ItemsSource="{Binding MySelectedProducts.productVM_List, Mode=TwoWay, 
                            UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True, 
                            ValidatesOnExceptions=True, NotifyOnValidationError=True}">
                <DataGrid.Columns>
                    <DataGridTextColumn Width="75" 
                                            Header="ProductID"
                                            Binding="{Binding ProductID, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True, 
                                            ValidatesOnExceptions=True, NotifyOnValidationError=True}" />
                    <DataGridTextColumn Width="150" 
                                            Header="ProductName"
                                            Binding="{Binding ProductName, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True, 
                                            ValidatesOnExceptions=True, NotifyOnValidationError=True}" />
                    <DataGridTextColumn Width="100" 
                                            Header="UnitsOnOrder"
                                            Binding="{Binding UnitsOnOrder, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True, 
                                            ValidatesOnExceptions=True, NotifyOnValidationError=True}" />
                </DataGrid.Columns>
            </DataGrid>
        </StackPanel>
        <StackPanel Grid.Row="2" Margin="5,0,0,0" FlowDirection="LeftToRight" Orientation="Horizontal" VerticalAlignment="Top"  HorizontalAlignment="Left" >
            <TextBlock Text="Order Detail List" Margin="5"></TextBlock>
            <DataGrid x:Name="grd2" AutoGenerateColumns="False"                           
                            ItemsSource="{Binding MySelectedOrderDetails.OrderDetailVM_List, Mode=TwoWay, 
                            UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True, 
                            ValidatesOnExceptions=True, NotifyOnValidationError=True}">
                <DataGrid.Columns>
                    <DataGridTextColumn Width="75" 
                                            Header="OrderID"
                                            Binding="{Binding OrderID, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True, 
                                            ValidatesOnExceptions=True, NotifyOnValidationError=True}" />
                    <DataGridTextColumn Width="150" 
                                            Header="ProductID"
                                            Binding="{Binding ProductID, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True, 
                                            ValidatesOnExceptions=True, NotifyOnValidationError=True}" />
                    <DataGridTextColumn Width="100" 
                                            Header="Quantity"
                                            Binding="{Binding Quantity, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True, 
                                            ValidatesOnExceptions=True, NotifyOnValidationError=True}" />
                    <DataGridTextColumn Width="100" 
                                            Header="UnitPrice"
                                            Binding="{Binding UnitPrice, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True, 
                                            ValidatesOnExceptions=True, NotifyOnValidationError=True}" />
                    <DataGridTextColumn Width="100" 
                                            Header="Discount"
                                            Binding="{Binding Discount, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True, ValidatesOnDataErrors=True, 
                                            ValidatesOnExceptions=True, NotifyOnValidationError=True}" />
                </DataGrid.Columns>
            </DataGrid>
        </StackPanel>
        
        <StackPanel Grid.Row="3" Margin="5,0,0,0" FlowDirection="LeftToRight" Orientation="Horizontal" VerticalAlignment="Top"  HorizontalAlignment="Left" >
            <TextBlock Text="Messages" Margin="5"></TextBlock>
            <TextBlock Text="{Binding Messages,  UpdateSourceTrigger=PropertyChanged}" />
        </StackPanel>
    </Grid>
</Window>

Imports System.Collections.ObjectModel
Imports System.ComponentModel
Imports NorthwindData
Public Class MainViewModel
    Implements INotifyPropertyChanged
#Region "declarations"
    Private Property _repository As NorthwindRepository
    Private Property _ordercollvm As OrderCollectionViewModel
    Private Property _myselectedorder As OrderViewModel
    Private Property _myselectedproducts As ProductCollectionViewModel
    Private Property _myselectedorderdetails As OrderDetailCollectionViewModel
    Private _savecommand As RelayCommand
    Private _errorlist As New Dictionary(Of String, String)
#End Region
#Region "constructors"
    Public Sub New(ByVal rep As NorthwindRepository)
        _repository = rep
        OrderCollectionVM = New OrderCollectionViewModel(_repository)
    End Sub
#End Region
#Region "properties"
    Public ReadOnly Property Messages As String
        Get
            Dim msg As String = ""
            For Each x In _errorlist
                msg = msg & x.Key & " " & x.Value
            Next
            Return msg
        End Get
    End Property
    Public Property ErrorList As Dictionary(Of String, String)
        Get
            Return _errorlist
        End Get
        Set(value As Dictionary(Of String, String))
            _errorlist = value
            OnPropertyChanged("ErrorList")
            OnPropertyChanged("Messages")
        End Set
    End Property
    Public Property OrderCollectionVM As OrderCollectionViewModel
        Get
            Return _ordercollvm
        End Get
        Set(value As OrderCollectionViewModel)
            _ordercollvm = value
            OnPropertyChanged("OrderCollectionVM")
        End Set
    End Property
    Public Property MySelectedOrder As OrderViewModel
        Get
            Return _myselectedorder
        End Get
        Set(value As OrderViewModel)
            _myselectedorder = value
            OnPropertyChanged("MySelectedOrder")
            MySelectedProducts = New ProductCollectionViewModel(_repository, MySelectedOrder.OrderProducts)
            MySelectedOrderDetails = New OrderDetailCollectionViewModel(_repository, MySelectedOrder.Order_Details)
        End Set
    End Property
    Public Property MySelectedProducts As ProductCollectionViewModel
        Get
            Return _myselectedproducts
        End Get
        Set(value As ProductCollectionViewModel)
            _myselectedproducts = value
            OnPropertyChanged("MySelectedProducts")
        End Set
    End Property
    Public Property MySelectedOrderDetails As OrderDetailCollectionViewModel
        Get
            Return _myselectedorderdetails
        End Get
        Set(value As OrderDetailCollectionViewModel)
            _myselectedorderdetails = value
            OnPropertyChanged("MySelectedOrderDetails")
        End Set
    End Property
    Public ReadOnly Property CanSave
        Get
            Return True
        End Get
    End Property
#End Region
#Region "methods"
    Public ReadOnly Property SaveRecordCommand() As ICommand
        Get
            If _savecommand Is Nothing Then
                Dim btnaction As New Action(Of Object)(AddressOf Me.SaveRecord)
                _savecommand = New RelayCommand(btnaction, Function(x) Me.CanSave)
            End If
            Return _savecommand
        End Get
    End Property
    Public Sub SaveRecord()
        Try
            Dim iret As Integer = 0
            ErrorList.Clear()
            iret = _repository.SaveChanges()
            Select Case iret
                Case -1
                    ErrorList = _repository.ErrorList
                Case 0
                    ErrorList.Add("Alert ", "No changes found")
                Case Else
                    ErrorList.Add("Success ", CStr(iret) & " changes saved")
            End Select
            If iret = -1 Then
            Else
                OnPropertyChanged("MainViewModel")
            End If
        Catch ex As Exception
            ErrorList.Add("View Model Error", ex.Message)
            If Not IsNothing(_repository.ErrorList) Then
                ErrorList = _repository.ErrorList
            End If
        Finally
            OnPropertyChanged("Messages")
        End Try
    End Sub
#End Region
#Region "INotifyPropertyChanged Members"
    ''' <summary>
    ''' Raised when a property on this object has a new value.
    ''' </summary>
    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
    ''' <summary>
    ''' Raises this object's PropertyChanged event.
    ''' </summary>
    ''' <param name="propertyName">The property that has a new value.</param>
    Protected Overridable Sub OnPropertyChanged(ByVal propertyName As String)
        Dim handler As PropertyChangedEventHandler = Me.PropertyChangedEvent
        If handler IsNot Nothing Then
            Dim e = New PropertyChangedEventArgs(propertyName)
            handler(Me, e)
        End If
    End Sub
#End Region ' INotifyPropertyChanged Members
End Class

Imports System.Collections.ObjectModel
Imports System.ComponentModel
Imports NorthwindData
Imports System.Data.Objects
Imports System.Data.Objects.DataClasses
Public Class OrderDetailCollectionViewModel
    Implements INotifyPropertyChanged
    Private Property _repository As NorthwindRepository
    Private Property _orderdetailvm_list As ObservableCollection(Of OrderDetailViewModel)
    Public Sub New(ByVal rep As NorthwindRepository)
        _repository = rep
        _orderdetailvm_list = New ObservableCollection(Of OrderDetailViewModel)
    End Sub
    Public Sub New(ByVal rep As NorthwindRepository, ByVal objlist As ObservableCollection(Of Order_Detail))
        _repository = rep
        _orderdetailvm_list = New ObservableCollection(Of OrderDetailViewModel)
        For Each obj In objlist
            _orderdetailvm_list.Add(New OrderDetailViewModel(rep, obj))
        Next
    End Sub
    Public Sub New(ByVal rep As NorthwindRepository, ByVal objlist As EntityCollection(Of Order_Detail))
        _repository = rep
        _orderdetailvm_list = New ObservableCollection(Of OrderDetailViewModel)
        For Each obj In objlist
            _orderdetailvm_list.Add(New OrderDetailViewModel(rep, obj))
        Next
    End Sub
    Public Property OrderDetailVM_List As ObservableCollection(Of OrderDetailViewModel)
        Get
            Return _orderdetailvm_list
        End Get
        Set(value As ObservableCollection(Of OrderDetailViewModel))
            _orderdetailvm_list = value
            OnPropertyChanged("OrderDetailVM_List")
        End Set
    End Property
#Region "INotifyPropertyChanged Members"
    ''' <summary>
    ''' Raised when a property on this object has a new value.
    ''' </summary>
    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
    ''' <summary>
    ''' Raises this object's PropertyChanged event.
    ''' </summary>
    ''' <param name="propertyName">The property that has a new value.</param>
    Protected Overridable Sub OnPropertyChanged(ByVal propertyName As String)
        Dim handler As PropertyChangedEventHandler = Me.PropertyChangedEvent
        If handler IsNot Nothing Then
            Dim e = New PropertyChangedEventArgs(propertyName)
            handler(Me, e)
        End If
    End Sub
#End Region ' INotifyPropertyChanged Members
End Class

Imports System.Collections.ObjectModel
Imports System.ComponentModel
Imports NorthwindData
Public Class OrderDetailViewModel
    Implements INotifyPropertyChanged
    Private Property _repository As NorthwindRepository
    Private Property _order_detail As Order_Detail
    Public Sub New(ByVal rep As NorthwindRepository, ByVal orderid As Integer, ByVal prodid As Integer)
        _repository = rep
        order_detail = rep.SelectOrderDetailByOrderIdandProductId(orderid, prodid)
    End Sub
    Public Sub New(ByVal rep As NorthwindRepository, ByVal obj As order_detail)
        _repository = rep
        Order_Detail = obj
    End Sub
    Public Sub New()
        _order_detail = New Order_Detail()
        _order_detail.OrderID = 0
        _order_detail.ProductID = 0
        _order_detail.Quantity = 0
        _order_detail.UnitPrice = 0
        _order_detail.Discount = 0
    End Sub
    Public Sub New(ByVal orderid As Integer, ByVal prodid As Integer, ByVal quantity As Integer, ByVal up As Decimal, ByVal dis As Single)
        _order_detail = New Order_Detail()
        _order_detail.OrderID = orderid
        _order_detail.ProductID = prodid
        _order_detail.Quantity = quantity
        _order_detail.UnitPrice = up
        _order_detail.Discount = dis
    End Sub
    Public Property Order_Detail As Order_Detail
        Get
            Return _order_detail
        End Get
        Set(value As Order_Detail)
            _order_detail = value
            OnPropertyChanged("order_detail")
        End Set
    End Property
    Public Property OrderID As Integer
        Get
            Return order_detail.OrderID
        End Get
        Set(value As Integer)
            order_detail.OrderID = value
            OnPropertyChanged("OrderID")
        End Set
    End Property
    Public Property ProductID As Integer
        Get
            Return order_detail.ProductID
        End Get
        Set(value As Integer)
            order_detail.ProductID = value
            OnPropertyChanged("ProductID")
        End Set
    End Property
    Public Property Quantity As Integer
        Get
            Return order_detail.Quantity
        End Get
        Set(value As Integer)
            order_detail.Quantity = value
            OnPropertyChanged("Quantity")
        End Set
    End Property
    Public Property UnitPrice() As Global.System.Decimal
        Get
            Return Order_Detail.UnitPrice
        End Get
        Set(value As Global.System.Decimal)
            Order_Detail.UnitPrice = value
            OnPropertyChanged("UnitPrice")
        End Set
    End Property
    Public Property Discount() As Global.System.Single
        Get
            Return Order_Detail.Discount
        End Get
        Set(value As Global.System.Single)
            Order_Detail.Discount = value
            OnPropertyChanged("Discount")
        End Set
    End Property
    Public ReadOnly Property ProductName As String
        Get
            Return Order_Detail.Product.ProductName
        End Get
    End Property
#Region "INotifyPropertyChanged Members"
    ''' <summary>
    ''' Raised when a property on this object has a new value.
    ''' </summary>
    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
    ''' <summary>
    ''' Raises this object's PropertyChanged event.
    ''' </summary>
    ''' <param name="propertyName">The property that has a new value.</param>
    Protected Overridable Sub OnPropertyChanged(ByVal propertyName As String)
        Dim handler As PropertyChangedEventHandler = Me.PropertyChangedEvent
        If handler IsNot Nothing Then
            Dim e = New PropertyChangedEventArgs(propertyName)
            handler(Me, e)
        End If
    End Sub
#End Region ' INotifyPropertyChanged Members
End Class

Imports System
Imports System.Data.Objects
Imports NorthwindData.NorthwindModel
Imports System.Collections.ObjectModel
Public Class NorthwindContext
    Inherits ObjectContext
    Public Property Categories As ObjectSet(Of Category)
    Public Property Products() As ObjectSet(Of Product)
    Public Property Customers() As ObjectSet(Of Customer)
    Public Property Orders As ObjectSet(Of Order)
    Public Property Order_Details As ObjectSet(Of Order_Detail)
    Public Sub New()
        MyBase.New("name=NorthwindEntities", "NorthwindEntities")
        Categories = CreateObjectSet(Of Category)()
        Products = CreateObjectSet(Of Product)()
        Customers = CreateObjectSet(Of Customer)()
        Orders = CreateObjectSet(Of Order)()
        Order_Details = CreateObjectSet(Of Order_Detail)()
    End Sub
End Class

Imports System.Collections.ObjectModel
Imports System.Data.Entity.Validation
Public Class NorthwindRepository
    Private Property _context As NorthwindContext
    Private Property _errors As New Dictionary(Of String, String)
    Public Sub New(ByVal context As NorthwindContext)
        _context = context
    End Sub
    Public Property ErrorList As Dictionary(Of String, String)
        Get
            Return _errors
        End Get
        Set(value As Dictionary(Of String, String))
            _errors = value
        End Set
    End Property
    Public Function SelectOrderDetailByOrderId(ByVal orderid As Integer) As ObservableCollection(Of Order_Detail)
        Dim results = From x In _context.Order_Details.Include("Product").Include("Order").Include("Product.Category")
              Where x.OrderID = orderid
              Select x
        Return New ObservableCollection(Of Order_Detail)(results)
    End Function
    Public Function SelectProductById(ByVal id As Integer) As Product
        Dim results = From x In _context.Products
              Where x.ProductID = id
              Select x
        Return results.FirstOrDefault
    End Function
    Public Function SelectOrderById(ByVal orderid As Integer) As Order
        Dim results = From x In _context.Orders
              Where x.OrderID = orderid
              Select x
        Return results.FirstOrDefault
    End Function
    Public Function SelectOrderById_inclusive(ByVal orderid As Integer) As Order
        Dim results = From x In _context.Orders.Include("Order_Details")
              Where x.OrderID = orderid
              Select x
        Return results.FirstOrDefault
    End Function
    Public Function SelectOrderDetailByOrderIdandProductId(ByVal orderid As Integer, ByVal prodid As Integer) As Order_Detail
        Dim results = From x In _context.Order_Details.Include("Product").Include("Order").Include("Product.Category")
              Where x.OrderID = orderid AndAlso x.ProductID = prodid
              Select x
        Return results.FirstOrDefault
    End Function
    Public Function SelectAllOrder() As ObservableCollection(Of Order)
        Dim results = From x In _context.Orders
                      Select x
        Return New ObservableCollection(Of Order)(results)
    End Function
    Public Function SelectAllProduct() As ObservableCollection(Of Product)
        Dim results = From x In _context.Products
                      Select x
        Return New ObservableCollection(Of Product)(results)
    End Function
    Public Function SelectProductByCategory(ByVal catid As Integer) As ObservableCollection(Of Product)
        Dim results = From x In _context.Products
                      Where x.CategoryID = catid
                      Select x
        Return New ObservableCollection(Of Product)(results)
    End Function
    Public Function SelectProductByOrderID(ByVal orderid As Integer) As ObservableCollection(Of Product)
        Dim results = (From p In _context.Products
                                      From o In _context.Orders
                                      From od In _context.Order_Details
                                      Where o.OrderID = od.OrderID AndAlso od.ProductID = p.ProductID AndAlso o.OrderID = orderid
                                      Select p)
        Return New ObservableCollection(Of Product)(results)
    End Function
    Public Function SelectAllCategory() As ObservableCollection(Of Category)
        Dim results = From x In _context.Categories
                      Select x
        Return New ObservableCollection(Of Category)(results)
    End Function
    Public Function SaveChanges() As Integer
        Dim inumchanges As Integer = 0
        Try
            inumchanges = _context.SaveChanges
        Catch ex As Exception
            inumchanges = -1
            Dim results As New Dictionary(Of String, String)
            results.Add("Unexpected Error", ex.Message)
            If Not IsNothing(ex.InnerException) Then
                Dim innermsg As String = ""
                If ex.Message = ex.InnerException.Message Then
                    innermsg = ex.InnerException.InnerException.Message
                Else
                    innermsg = ex.InnerException.Message
                End If
                results.Add("Unexpected Error", innermsg)
            End If
            _errors = results
        End Try
        Return inumchanges
    End Function
End Class

Answer 4

Hi pretzelb,

I am working on your issue, I will follow up your issue later.

best regards,

---

Sheldon _Xiao[MSFT]
MSDN Community Support | Feedback to us
Microsoft
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

Answer 5

Sheldon

I uploaded a demo project to skydrive to try and show the issue. The demo attempts to keep it simple with basic objects like Employees, Product Lines, and Clients. But it does get involved with this simple model. It also includes initialization to create test data.

In the demo the grid on the left binds to an observable collection of entities via a CollectionViewSource. This left grid works fine. Add, update, and delete all function.

The grid on the right bings to a view model that is a collection of other view models. The Client Allocation entity is loaded into a Client Allocation view model and a collection of those are loaded into the Client Allocation Collection view model. The grid on the right binds to this collection view model but add and deletes are not transmitted to the underlying EmpDetailMaster entity.

Hopefully this helps.

Answer 6

You might look at MVVM approach http://blogs.msdn.com/b/ivo_manolov/archive/2012/03/17/10284665.aspx.

---

Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Regards,
Jacky Wu
Microsoft Online Community Support

Answer 7

You might look at MVVM approach http://blogs.msdn.com/b/ivo_manolov/archive/2012/03/17/10284665.aspx.

---

Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Regards,
Jacky Wu
Microsoft Online Community Support

I am using MVVM.

Answer 8

I am still not sure what is common out there for others but I've decided that if I want to use MVVM in such a way that each entity has it's own view model and a collection of view models is also represented by a view model, then I need to generate the support structure to fix the links broken by copying from the context to the view model. For example, a delete on a child record like ClientMapping needs to trigger an event to communicate not only to the collection of of ClientMapping records in the view model, but also to the MappingRecord entity which then needs to update it's collection under the Clients() property (which is linked to the context).

Answer 9

Hi Pretzelb,

Sorry for interup. The following information is not related to this thread and it is about another thread.

It seems Sheldon moved your thread http://social.msdn.microsoft.com/Forums/en-US/adonetefx/thread/2b21df9c-e55f-40b8-9c66-573dc68ee95a to an achieved forum by mistake. That forum is locked and cannot be replied.

That question will have better support in EF forum http://social.msdn.microsoft.com/Forums/en/adodotnetentityframework/threads.

Could you please re-post that question in EF forum? Our data guy will help you there.

Thanks for your understanding and support!

Best regards,

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Min Zhu [MSFT]
MSDN Community Support | Feedback to us