Added new kb article remembering-restoring-expanded-rows-treedatagrid-dotnet-maui

Author: KB Bot

knowledge-base/remembering-restoring-expanded-rows-treedatagrid-dotnet-maui.md

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+---
+title: Remembering and Restoring Expanded Rows in TreeDataGrid for .NET MAUI
+description: Learn how to efficiently remember expanded rows and restore them in TreeDataGrid for .NET MAUI.
+type: how-to
+page_title: Efficiently Remember and Restore Expanded Rows in TreeDataGrid for .NET MAUI
+meta_title: Efficiently Remember and Restore Expanded Rows in TreeDataGrid for .NET MAUI
+slug: remembering-restoring-expanded-rows-treedatagrid-dotnet-maui
+tags: treedatagrid, .net maui, expand, collapse, isexpanded, isexpandablebinding
+res_type: kb
+---
+
+## Environment
+
+| Version | Product | Author | 
+| --- | --- | ---- | 
+| 11.1.0 | Telerik UI for .NET MAUI TreeDataGrid | [Dobrinka Yordanova](https://www.telerik.com/blogs/author/dobrinka-yordanova) | 
+
+## Description
+
+I want to remember the expanded rows in the TreeDataGrid and restore them later. What is the most efficient way to achieve this?
+
+This knowledge base article also answers the following questions:
+- How can I store expanded items in TreeDataGrid for later use?
+- How can I restore the expansion state in TreeDataGrid after changes?
+- What is the best way to manage expanded rows in TreeDataGrid?
+
+## Solution
+
+To achieve the scenario you can use one of the following approaches:
+* [Using `Expand` and `Collapse` Methods](#using-expand-and-collapse-methods)
+* [Using `IsExpandableBinding` property of the `TreeDataGridDescriptor`](#using-isexpandablebinding)
+
+### Using Expand and Collapse Methods
+
+To achieve this, follow these steps:
+
+1. Use `Expand()` and `Collapse()` methods to expand or collapse items.
+2. Use the `IsExpanded` method to check whether an item is expanded.
+3. Store the expanded items in a collection, such as a `List<YourDataClass>`.
+4. Iterate through the collection to restore the expanded state by calling the `Expand()` method.
+
+```C#
+public partial class MainPage : ContentPage
+{
+    public MainPage()
+    {
+        InitializeComponent();
+        this.BindingContext = new ViewModel();
+    }
+
+    // Collection for storing expanded items
+    List<Data> expandedItems = new List<Data>();
+
+    private void Button_Clicked(object sender, EventArgs e)
+    {
+        var items = (IEnumerable)this.tdg.ItemsSource;
+        this.expandedItems = new List<Data>();
+        AddExpandedItems(items, expandedItems);
+    }
+
+    private void AddExpandedItems(IEnumerable items, List<Data> expandedItems)
+    {
+        foreach (Data item in items)
+        {
+            if (this.tdg.IsExpanded(item))
+            {
+                expandedItems.Add(item);
+            }
+
+            IEnumerable childrenOfTheItem = item.Children;
+            AddExpandedItems(childrenOfTheItem, expandedItems);
+        }
+    }
+
+    private void Button2_Clicked(object sender, EventArgs e)
+    {
+        foreach (Data item in this.expandedItems)
+        {
+            this.tdg.Expand(item);
+        }
+    }
+}
+```
+
+### Using `IsExpandableBinding`
+
+As an alternative, use the [`IsExpandableBinding`](https://docs.telerik.com/devtools/maui/controls/treedatagrid/descriptor) property at the descriptor level:
+
+1. Add a `bool` property in the data model to indicate whether an item is expandable.
+2. Bind this property to the `IsExpandableBinding` property of the TreeDataGrid descriptor.
+3. Implement the logic in button clicks to get and restore expanded items.
+
+This approach provides direct control over the expandability of rows via data binding.
+
+## See Also
+
+- [TreeDataGrid Overview](https://docs.telerik.com/devtools/maui/controls/treedatagrid/overview)
+- [Expand and Collapse Methods in TreeDataGrid](https://docs.telerik.com/devtools/maui/controls/treedatagrid/methods)