CollectionViewSource is not triggering the filter event when refresh is called

Question

The idea is, I have a textbox in which I type a string, this string will filter the collectionviewsource which is a treeview. Attaching the code below:

The sorting and grouping are working fine.

View.xaml

<TreeView x:Name="SystemsTreeView" ItemsSource="{Binding Source={StaticResource SystemCollection}, Path=Groups}">

     <CollectionViewSource x:Key="SystemCollection" Source="{Binding SystemsList}" Filter="SystemCollectionChangeFilter" IsLiveFilteringRequested="True" >   
        <CollectionViewSource.LiveFilteringProperties>
                        <clr:String>SystemName</clr:String>
                        <clr:String>Version</clr:String>
                    </CollectionViewSource.LiveFilteringProperties>
        <!--Sorting of Systems--> 
        <CollectionViewSource.SortDescriptions>
            <scm:SortDescription PropertyName="SystemName"/>
            <scm:SortDescription PropertyName="Version" Direction="Descending"/>
        </CollectionViewSource.SortDescriptions>
         <!--Grouping of Systems--> 
        <CollectionViewSource.GroupDescriptions>
            <PropertyGroupDescription PropertyName="SystemName" />
        </CollectionViewSource.GroupDescriptions>                
    </CollectionViewSource>

The SystemCollectionChangeFilter calls the method on the viewmodel to filter.

ViewModel

ICollectionView viewSource = CollectionViewSource.GetDefaultView(SystemsList); //in the constructor


private string _systemNameFilter;

public string SystemNameFilter //Attached to Textbox (for filtering)
{
   get { return _systemNameFilter; }
   set
   {
      if (_systemNameFilter != value)
         {
            _systemNameFilter = value;
             viewSource.Refresh();  //This is not triggering the filtering event.  
             NotifyPropertyChanged();
         }
    }
}

The viewSource.Refresh() is not triggering the filter event on the collectionviewsource. I have checked that the filtering event is only triggered when the usercontrol is loaded.

Tried so far:

I have also tried by keeping LiveFilteringRequested property to true in xaml and also tried to add the CollectionViewType, but none of it is working.
Trigger Filter on CollectionViewSource, this solution requires me to keep the stuff in viewmodel rather than in xaml which is a problem for me.

Would be helpful if you can recommend any mvvm based solution for the above problem.

Call `Refresh` on the `CollectionViewSource` in the view or add your property to the `LiveFilteringProperties` collection of the same. — mm8, Mar 11 '20 at 13:39
Added the LiveFilteringProperties but no change. Can you please tell me how to call the refresh in the view in mvvm? — SmallestWish, Mar 11 '20 at 13:54
Define an `ICollectionView`, or any other type of source collection, in the view model and operate on this one. It makes no sense to define the sorting and filtering in the view and then try to refresh it from the view model. This is not MVVM. Keep the logic in the view model *or* in the view. — mm8, Mar 11 '20 at 13:57
To change my collection to ICollection in the viewmodel and do the sorting, grouping and filtering in viewmodel would be then my last resort, and then I will change my question, but since I do not want to change big now, is there a way that I can put my filtering logic in view only? could u please provide this, I will mark it as an answer. I didnt find the filtering logic in view anywhere. Thank you — SmallestWish, Mar 11 '20 at 14:08
Did you try to call `Refresh` on the `CollectionViewSource` named "SystemCollection"? — mm8, Mar 11 '20 at 14:15
ah yes!, I tried it, its working. I dont know why the ICollectionView I got in the viewmodel is not refreshing, as the refreshing of CollectionView of the view is working. Anyhow, thats the question, so if u can make it as an answer I will mark it. Thanks, still looking how the logic for filtering can be put in the view. :) — SmallestWish, Mar 11 '20 at 14:35

score 0 · Accepted Answer · answered Mar 11 '20 at 15:00

Call Refresh() on the CollectionViewSource named "SystemCollection" in the view or implement an ICollectionView, or any other type of source collection, in the view model and refresh it from there.

Adding LiveFilteringProperties should also work provided that the generated CollectionView implements the ICollectionViewLiveShaping interface.

CollectionViewSource is not triggering the filter event when refresh is called

1 Answers1