[Enhancement] Allow to maually deselect item from CollectionView

[HobDev]

Summary

In many scenarios developer would require to programmatically needs to deselect a selected item. I tried to do so by binding SelectedItem to a property in ViewModel. I am assigning it a value of null to deselect the selected item. But that does not work.

[pinoelefante]

I am using a workaround. I have added a Tapped event handler to the ItemTemplate and using this code

private void ItemTapped(object sender, EventArgs e)
{
    if (e is TappedEventArgs)
    {
        var ev = e as TappedEventArgs;
        var collection = ((sender as Element).Parent as CollectionView);

        if (collection.SelectedItem == ev.Parameter)
            collection.SelectedItem = null;
        else
            collection.SelectedItem = ev.Parameter;
    }
}

[hartez]

Once PR #6085 is merged, setting SelectedItem to null will clear the selection.

[BrayanKhosravian]

this seems not to work anymore for me

[BrayanKhosravian]

setting the selected item to null dosnt reset the selection

[hartez]

@BrayanKhosravian Which version of Forms? And on which platform?

[BrayanKhosravian]

Wow that was a very fast response. Thanks :D

Latest stable release of xamarin forms (4.4.0.99142).
Tested on UWP.

But before you invest some time to investigate, let me check it one more time.
I just switched from listview to collectionview.

Is it fine for you to notify you here?

[BrayanKhosravian]

im online on gitter as well

[hartez]

Is it fine for you to notify you here?

This is always the correct place for that.

Also, since you said it was happening on UWP, I wonder if you're seeing this bug: #8842

[BrayanKhosravian]

oh yes its exactly the bug.
i tried to unselect it by multiple ways.

private void IngredientSelected(object sender, SelectedItemChangedEventArgs e)
	    {
		    if(e is null) return;
		    ((CollectionView) sender).SelectedItem = null;
                    e.CurrentSelection = null;
                    IngredientCollectionView.SelectedItem = null;
	    }

[BrayanKhosravian]

but none worked actually. i tought that i made a mistake in my source.
but i actually found another issue as well.
but its not related to this bug report.

[Tuytje]

I had the same problem and found a solution by wrapping the SelectedItem = null in a UI call for UWP:
Device.BeginInvokeOnMainThread(() => SelectedItem = null);

I'm working with a ViewModel with a TwoWay Binded SelectedItem

[drejoh63]

I had the same problem and found a solution by wrapping the SelectedItem = null in a UI call for UWP: Device.BeginInvokeOnMainThread(() => SelectedItem = null);

I'm working with a ViewModel with a TwoWay Binded SelectedItem

This solved my issue