WPF Binding to ListView using different instance of viewmodel - wpf

Question

I am having an issue binding an observable collection of viewmodels to a ListView.
Theres something interesting however which allows me to bind successfully which shows the code is correct ( as far as I can see )
The scenario:
I have 1 main screen which uses 'MainViewModel'
This mainviewmodel has a ListView which binds to a 'OpenSaleViewModel' which in turn has an observable collection of 'OpenSaleItemViewModel' objects.
The code I have in XAML works fine : The DisplayMemberBinding works fine
<Grid x:Name="SalesScreenHolder" Background="AliceBlue" VerticalAlignment="Stretch" >
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="70" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Grid x:Name="grdSalesWindow" Margin="0,0,0,0" Grid.Row="0" Width="300" Height="350" MaxHeight="1000" DataContext="{Binding Main, Source={StaticResource MainVM}}">
<ScrollViewer x:Name="salesScrollViewer" PanningMode="VerticalOnly" VerticalScrollBarVisibility="Hidden" HorizontalScrollBarVisibility="Hidden" >
<ListView x:Name="lstviewSales" ItemContainerStyle="{StaticResource alternatingListViewItemStyle}" AlternationCount="2" HorizontalAlignment="Left" HorizontalContentAlignment="Left" ItemsSource="{Binding OpenSale.OpenSalesItems, UpdateSourceTrigger=PropertyChanged}">
<!--<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<Setter Property="Height" Value="30" />
</Style>
</ListView.ItemContainerStyle>-->
<ListView.View>
<GridView x:Name="listViewGrid">
<GridViewColumn Width="150" Header="Item"
DisplayMemberBinding="{Binding SaleItemName}" />
<GridViewColumn Width="50" Header="Qty"
DisplayMemberBinding="{Binding Quantity}" />
<GridViewColumn Width="90" Header="TotalPrice"
DisplayMemberBinding="{Binding TotalAmtString}" />
</GridView>
</ListView.View>
</ListView>
</ScrollViewer>
Now say I have 4 OpenSaleViewModel objects, 1 for each sale and each has its own collection of SalesItems
I try and bind the collection to a dialog window i open elsewhere in the application and it only shows me the namespace and the name of the viewmodel : see screenshot
I have tried using path=PROPERTYNAME and Data.PROPERTYNAME
The datacontext IS set as I am accessing properties in the parent viewmodel and binding successfully as you can see in the 3 labels above the grid. I have debugged and can see that the correct amount of items are picked up for each sale but the data is not recnoginized.
The thing is if i set 'ItemsSource="{Binding OpenSale.OpenSalesItems' to be 'ItemsSource="{Binding OpenSale' just to test what happens in the MAIN Screen, this means there is no data to bind against, so it seems that when the observable collection is null in the Main Screen, my dialog window does display the data ok - so i cant understand why 2 different viewmodels with different collections ( using the same class as the basis of the collection though ) seems to be conflicting??
It seems I can only bind when only 1 window is using a collection of the same type of viewmodel ( in this case 'SaleItems' within the sale viewmodel )
This is the code for my dialog window
<Grid x:Name="grdTableSalesItemsxxc" Margin="2,0,2,0" Grid.Row="0" Width="610" Height="200" MaxHeight="1000" >
<ScrollViewer x:Name="tableSalesScrollViewer" PanningMode="VerticalOnly" VerticalScrollBarVisibility="Hidden" HorizontalScrollBarVisibility="Hidden" >
<ListView x:Name="lstviewTableSalexxc" ItemContainerStyle="{StaticResource alternatingListViewItemStyle}" AlternationCount="2"
HorizontalAlignment="Stretch" HorizontalContentAlignment="Left" ItemsSource="{Binding Sale.OpenSalesItems, BindsDirectlyToSource=True, UpdateSourceTrigger=PropertyChanged}" >
<!--<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<Setter Property="Height" Value="30" />
</Style>
</ListView.ItemContainerStyle>-->
<ListView.View>
<GridView x:Name="grdTableSaleGridxxc">
<GridViewColumn Width="295" Header="Item Name"
DisplayMemberBinding="{Binding SaleItemName}" />
<!--<GridViewColumn Width="100" Header="Quantity"
DisplayMemberBinding="{Binding SaleItemName}" />
<GridViewColumn Width="105" Header="Total Price"
DisplayMemberBinding="{Binding SaleItemName}" />-->
</GridView>
</ListView.View>
</ListView>
</ScrollViewer>
This is the collection from the parent viewmodel 'OpenSaleViewModel' which binds first time in the main screen
public ObservableCollection<OpenSaleItemViewModel> OpenSalesItems
{
get
{
if (_salesItems == null)
{
_salesItems = new ObservableCollection<OpenSaleItemViewModel>();
foreach (OpenSaleItem itm in _openSale.OpenSaleItems)
{
// Check if we need to grab the stockPLU or RecipeProduct PLU
if (itm.StockPLU != null)
{
_osi = new OpenSaleItemViewModel(itm.StockPLU);
}
else
{
_osi = new OpenSaleItemViewModel(itm.RecipeProductID);
}
// Populate remaining properties
_osi.Quantity = itm.Quantity;
_osi.TotalAmount = itm.TotalAmount;
_osi.SalesUnitCostPrice = itm.SalesUnitCostPrice;
if (itm.OpenSale != null)
_osi.OpenSaleID = itm.OpenSale.ID;
_salesItems.Add(_osi);
}
}
return _salesItems;
}
set
{
_salesItems = value;
RaisePropertyChanged("OpenSalesItems");
RaisePropertyChanged("TotalVAT");
RaisePropertyChanged("TotalAmtIncVAT");
}
}

Answer 1

I feel like your ItemsSource should be set on your GridView an not on your ListView. Did that not work for you?