Question

I have 3 controls on my page

• ListBox A
• ListBox B
• ComboBox C

ListBox A is databound to a collection of items A

ComboBox C is databound to a collection of items C

ListBox B is databound to a collection of items B

B has a reference to Item A and Item C, the ListBox B should only show the items where Item A is the selected item of ListBox A, and Item C is the selected item of ListBox C

i’ve messed a little with collectionviews as ItemSource on ListBox B, setting a filter, but I can only get it to update the content of ListBox B based on either ListBox A or ComboBox C, not them both at the same time.

Any ideas?

Answer 1

In your view model, give the CollectionView a filter predicate, something like this:

Items = CollectionViewSource.GetDefaultView(_Items) as CollectionView;
Items.Filter = (x => ((Item)x).CategoryA == SelectedCategoryA 
                && ((Item)x).CategoryC == SelectedCategoryC);

Bind the list/combo boxes’ SelectedItem to SelectedCategoryA and SelectedCategoryC properties. In the setters for those properties, call Items.Refresh().

Edit

In your list box, bind both ItemsSource and SelectedItem, e.g.

<ListBox ItemsSource="{Binding CategoryListA}"
         SelectedItem="{Binding SelectedCategoryA, Mode=TwoWay}"/>

In your view model, create a property like this:

private Category _SelectedCategoryA;

public Category SelectedCategoryA
{
   get { return _SelectedCategoryA; }
   set
   {
      if (value != _SelectedCategoryA)
      {
         _SelectedCategoryA = value;
         Items.Refresh();
      }
   }
}