Merge pull request #1136 from telerik/new-kb-collectionview-maui-dragdrop-notify-viewmodel-871e4be7defe4d58903d4830e5c268fe

Added new kb article collectionview-maui-dragdrop-notify-viewmodel

Author: didiyordanova

knowledge-base/collectionview-maui-dragdrop-notify-viewmodel.md

@@ -0,0 +1,61 @@
+---
+title: Using the Drop Method in DragDropBehavior with CollectionView for .NET MAUI
+description: Learn how to notify the view model about drag-and-drop actions in CollectionView for .NET MAUI using the Drop method in DragDropBehavior.
+type: how-to
+page_title: Handling DragDropBehavior in CollectionView for .NET MAUI
+slug: collectionview-maui-dragdrop-notify-viewmodel
+tags: collectionview, .net maui, dragdropbehavior, drop-method, viewmodel
+res_type: kb
+---
+
+## Environment
+
+| Version | Product | Author | 
+| --- | --- | ---- | 
+| 10.1.0 | Telerik UI for .NET MAUI CollectionView |[Dobrinka Yordanova](https://www.telerik.com/blogs/author/dobrinka-yordanova) | 
+
+
+## Description
+
+I want to notify the view model when drag-and-drop actions are performed in the [CollectionView for .NET MAUI](https://docs.telerik.com/devtools/maui/controls/collectionview/overview). Unlike the `RadListView.ReorderEnded` event, CollectionView uses `DragDropBehavior`, but it isn't clear how to inform the view model of the drop action. 
+
+This knowledge base article also answers the following questions:
+- How to handle drag-and-drop in CollectionView for .NET MAUI?
+- How to use the `Drop` method of `DragDropBehavior` in CollectionView?
+- How to notify a view model of drag-and-drop actions in CollectionView for .NET MAUI?
+
+## Solution
+
+To notify the view model of drag-and-drop actions in the CollectionView for .NET MAUI, use the `Drop` method in the `DragDropBehavior`. This method is triggered when an item is dropped. You can call this method within the context of the behavior to handle the drag-and-drop operation.
+
+### Example
+Here is an example of implementing the `Drop` method:
+
+```csharp
+public class CustomDragDropBehavior : CollectionViewDragDropBehavior
+{
+    public override void Drop(CollectionViewDragDropContext state)
+    {
+        var collectionView = this.CollectionView;
+        if (collectionView != null)
+        {
+            base.Drop(state);
+            // Notify the view model about the drop action
+            var viewModel = collectionView.BindingContext as YourViewModel;
+            // add your logic here
+        }
+    }
+}
+```
+
+### Key Points
+
+1. Override the `Drop` method in a custom behavior class.
+2. Access the `CollectionView`.
+3. Notify the view model by invoking a method or updating properties.
+
+For additional information on drag-and-drop functionality, refer to the [DragDrop Grouped Items documentation](https://docs.telerik.com/devtools/maui/controls/collectionview/drag-and-drop/dragdrop-grouped-items).
+
+## See Also
+
+- [CollectionView Drag-and-Drop Overview](https://docs.telerik.com/devtools/maui/controls/collectionview/drag-and-drop/overview)