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| 1 | +--- |
| 2 | +title: Remembering and Restoring Expanded Rows in TreeDataGrid for .NET MAUI |
| 3 | +description: Learn how to efficiently remember expanded rows and restore them in TreeDataGrid for .NET MAUI. |
| 4 | +type: how-to |
| 5 | +page_title: Efficiently Remember and Restore Expanded Rows in TreeDataGrid for .NET MAUI |
| 6 | +meta_title: Efficiently Remember and Restore Expanded Rows in TreeDataGrid for .NET MAUI |
| 7 | +slug: remembering-restoring-expanded-rows-treedatagrid-dotnet-maui |
| 8 | +tags: treedatagrid, .net maui, expand, collapse, isexpanded, isexpandablebinding |
| 9 | +res_type: kb |
| 10 | +--- |
| 11 | + |
| 12 | +## Environment |
| 13 | + |
| 14 | +| Version | Product | Author | |
| 15 | +| --- | --- | ---- | |
| 16 | +| 11.1.0 | Telerik UI for .NET MAUI TreeDataGrid | [Dobrinka Yordanova](https://www.telerik.com/blogs/author/dobrinka-yordanova) | |
| 17 | + |
| 18 | +## Description |
| 19 | + |
| 20 | +I want to remember the expanded rows in the TreeDataGrid and restore them later. What is the most efficient way to achieve this? |
| 21 | + |
| 22 | +This knowledge base article also answers the following questions: |
| 23 | +- How can I store expanded items in TreeDataGrid for later use? |
| 24 | +- How can I restore the expansion state in TreeDataGrid after changes? |
| 25 | +- What is the best way to manage expanded rows in TreeDataGrid? |
| 26 | + |
| 27 | +## Solution |
| 28 | + |
| 29 | +To achieve the scenario you can use one of the following approaches: |
| 30 | +* [Using `Expand` and `Collapse` methods](#using-expand-and-collapse-methods) |
| 31 | +* [Using `IsExpandableBinding` property of the `TreeDataGridDescriptor`](#using-isexpandablebinding) |
| 32 | + |
| 33 | +### Using Expand and Collapse Methods |
| 34 | + |
| 35 | +To achieve this, follow these steps: |
| 36 | + |
| 37 | +1. Use `Expand()` and `Collapse()` methods to expand or collapse items. |
| 38 | +2. Use the `IsExpanded` method to check whether an item is expanded. |
| 39 | +3. Store the expanded items in a collection, such as a `List<YourDataClass>`. |
| 40 | +4. Iterate through the collection to restore the expanded state by calling the `Expand()` method. |
| 41 | + |
| 42 | +```C# |
| 43 | +public partial class MainPage : ContentPage |
| 44 | +{ |
| 45 | + public MainPage() |
| 46 | + { |
| 47 | + InitializeComponent(); |
| 48 | + this.BindingContext = new ViewModel(); |
| 49 | + } |
| 50 | + |
| 51 | + // Collection for storing expanded items |
| 52 | + List<Data> expandedItems = new List<Data>(); |
| 53 | + |
| 54 | + private void Button_Clicked(object sender, EventArgs e) |
| 55 | + { |
| 56 | + var items = (IEnumerable)this.tdg.ItemsSource; |
| 57 | + this.expandedItems = new List<Data>(); |
| 58 | + AddExpandedItems(items, expandedItems); |
| 59 | + } |
| 60 | + |
| 61 | + private void AddExpandedItems(IEnumerable items, List<Data> expandedItems) |
| 62 | + { |
| 63 | + foreach (Data item in items) |
| 64 | + { |
| 65 | + if (this.tdg.IsExpanded(item)) |
| 66 | + { |
| 67 | + expandedItems.Add(item); |
| 68 | + } |
| 69 | + |
| 70 | + IEnumerable childrenOfTheItem = item.Children; |
| 71 | + AddExpandedItems(childrenOfTheItem, expandedItems); |
| 72 | + } |
| 73 | + } |
| 74 | + |
| 75 | + private void Button2_Clicked(object sender, EventArgs e) |
| 76 | + { |
| 77 | + foreach (Data item in this.expandedItems) |
| 78 | + { |
| 79 | + this.tdg.Expand(item); |
| 80 | + } |
| 81 | + } |
| 82 | +} |
| 83 | +``` |
| 84 | + |
| 85 | +### Using `IsExpandableBinding` |
| 86 | + |
| 87 | +As an alternative, use the [`IsExpandableBinding`](https://docs.telerik.com/devtools/maui/controls/treedatagrid/descriptor) property at the descriptor level. This approach provides direct control over the expandability of rows via data binding. |
| 88 | + |
| 89 | +1. Add a `bool` property in the data model to indicate whether an item is expandable. |
| 90 | +2. Bind this property to the `IsExpandableBinding` property of the TreeDataGrid descriptor. |
| 91 | +3. Implement the logic in button clicks to get and restore expanded items. |
| 92 | + |
| 93 | +## See Also |
| 94 | + |
| 95 | +- [TreeDataGrid Overview](https://docs.telerik.com/devtools/maui/controls/treedatagrid/overview) |
| 96 | +- [Expand and Collapse Methods in TreeDataGrid](https://docs.telerik.com/devtools/maui/controls/treedatagrid/methods) |
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