# TreeNodeExtensions

Namespace: **Wisej.Web.Markup**

Assembly: **Wisej.Framework** (4.0.0.0)

Adds [fluent markup](https://learn.microsoft.com/en-us/dotnet/communitytoolkit/maui/markup/markup) extension methods to the [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md) class.

{% tabs %}
{% tab title="C#" %}

```csharp
public class TreeNodeExtensions
```

{% endtab %}

{% tab title="VB.NET" %}

```visual-basic
Public Class TreeNodeExtensions
```

{% endtab %}
{% endtabs %}

## Methods

### ![](/files/lIX317sDtMTZJBi9oSIx) Checked\<TTreeNode>(treeNode, value)

Sets the checked state of the tree node.

| Parameter     | Type                                                                                 | Description                                                                                                                   |
| ------------- | ------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md) | The tree node to set the checked state on.                                                                                    |
| **value**     | [Boolean](https://docs.microsoft.com/dotnet/api/system.boolean)                      | A boolean value indicating whether the node is checked.                                                                       |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The modified tree node with the checked state set.

### ![](/files/lIX317sDtMTZJBi9oSIx) LazyLoading\<TTreeNode>(treeNode, value)

Sets the lazy loading property of the tree node.

| Parameter     | Type                                                                                 | Description                                                                                                                   |
| ------------- | ------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md) | The tree node to set the lazy loading property on.                                                                            |
| **value**     | [Boolean](https://docs.microsoft.com/dotnet/api/system.boolean)                      | A boolean value indicating whether lazy loading is enabled.                                                                   |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The modified tree node with the lazy loading property set.

### ![](/files/lIX317sDtMTZJBi9oSIx) Nodes\<TTreeNode>(treeNode, nodes)

Adds an array of child nodes to the specified [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md).

| Parameter     | Type                                                                                 | Description                                                                                                                   |
| ------------- | ------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md) | The tree node to which the child nodes will be added.                                                                         |
| **nodes**     | [TreeNode\[\]](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md)        | An array of tree nodes to be added as children.                                                                               |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The tree node with the updated child nodes.

This method allows you to add multiple child nodes to a tree node in a tree view control.

```csharp

myTreeNode.Nodes(new TreeNode("Child1"), new TreeNode("Child2"));

```

### ![](/files/lIX317sDtMTZJBi9oSIx) OnAfterCheck\<TTreeNode>(treeNode, action)

Attaches an action to be executed after the tree node is checked.

| Parameter     | Type                                                                                 | Description                                                                                                                   |
| ------------- | ------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md) | The tree node to attach the action to.                                                                                        |
| **action**    | [Action\<TTreeNode>](https://docs.microsoft.com/dotnet/api/system.action-1)          | The action to execute after the node is checked.                                                                              |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The tree node with the action attached.

This method allows you to perform custom logic after a tree node's checked state changes.

```csharp

treeNode.OnAfterCheck(node => { /* custom logic */ });

```

### ![](/files/lIX317sDtMTZJBi9oSIx) OnAfterCollapse\<TTreeNode>(treeNode, action)

Attaches an action to be executed after the tree node is collapsed.

| Parameter     | Type                                                                                 | Description                                                                                                                   |
| ------------- | ------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md) | The tree node to attach the action to.                                                                                        |
| **action**    | [Action\<TTreeNode>](https://docs.microsoft.com/dotnet/api/system.action-1)          | The action to execute after the node is collapsed.                                                                            |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The tree node with the action attached.

This method allows you to perform custom logic after a tree node is collapsed.

```csharp

treeNode.OnAfterCollapse(node => { /* custom logic */ });

```

### ![](/files/lIX317sDtMTZJBi9oSIx) OnAfterExpand\<TTreeNode>(treeNode, action)

Attaches an action to be executed after the tree node is expanded.

| Parameter     | Type                                                                                 | Description                                                                                                                   |
| ------------- | ------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md) | The tree node to attach the action to.                                                                                        |
| **action**    | [Action\<TTreeNode>](https://docs.microsoft.com/dotnet/api/system.action-1)          | The action to execute after the node is expanded.                                                                             |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The tree node with the action attached.

This method allows you to perform custom logic after a tree node is expanded.

```csharp

treeNode.OnAfterExpand(node => { /* custom logic */ });

```

### ![](/files/lIX317sDtMTZJBi9oSIx) OnAfterSelect\<TTreeNode>(treeNode, action)

Attaches an action to be executed after the tree node is selected.

| Parameter     | Type                                                                                 | Description                                                                                                                   |
| ------------- | ------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md) | The tree node to attach the action to.                                                                                        |
| **action**    | [Action\<TTreeNode>](https://docs.microsoft.com/dotnet/api/system.action-1)          | The action to execute after the node is selected.                                                                             |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The tree node with the action attached.

This method allows you to perform custom logic after a tree node is selected.

```csharp

treeNode.OnAfterSelect(node => { /* custom logic */ });

```

### ![](/files/lIX317sDtMTZJBi9oSIx) OnBeforeCheck\<TTreeNode>(treeNode, action)

Attaches an action to be executed before the tree node is checked.

| Parameter     | Type                                                                                                 | Description                                                                                                                   |
| ------------- | ---------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md)                 | The tree node to attach the action to.                                                                                        |
| **action**    | [Action\<TTreeNode, TreeViewCancelEventArgs>](https://docs.microsoft.com/dotnet/api/system.action-2) | The action to execute before the node is checked.                                                                             |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The tree node with the action attached.

This method allows you to perform custom logic before a tree node's checked state changes.

```csharp

treeNode.OnBeforeCheck((node, args) => { /* custom logic */ });

```

### ![](/files/lIX317sDtMTZJBi9oSIx) OnBeforeCollapse\<TTreeNode>(treeNode, action)

Attaches an action to be executed before the tree node is collapsed.

| Parameter     | Type                                                                                                 | Description                                                                                                                   |
| ------------- | ---------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md)                 | The tree node to attach the action to.                                                                                        |
| **action**    | [Action\<TTreeNode, TreeViewCancelEventArgs>](https://docs.microsoft.com/dotnet/api/system.action-2) | The action to execute before the node is collapsed.                                                                           |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The tree node with the action attached.

This method allows you to perform custom logic before a tree node is collapsed.

```csharp

treeNode.OnBeforeCollapse((node, args) => { /* custom logic */ });

```

### ![](/files/lIX317sDtMTZJBi9oSIx) OnBeforeExpand\<TTreeNode>(treeNode, action)

Attaches an action to be executed before the tree node is expanded.

| Parameter     | Type                                                                                                 | Description                                                                                                                   |
| ------------- | ---------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md)                 | The tree node to attach the action to.                                                                                        |
| **action**    | [Action\<TTreeNode, TreeViewCancelEventArgs>](https://docs.microsoft.com/dotnet/api/system.action-2) | The action to execute before the node is expanded.                                                                            |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The tree node with the action attached.

This method allows you to perform custom logic before a tree node is expanded.

```csharp

treeNode.OnBeforeExpand((node, args) => { /* custom logic */ });

```

### ![](/files/lIX317sDtMTZJBi9oSIx) OnBeforeSelect\<TTreeNode>(treeNode, action)

Attaches an action to be executed before the tree node is selected.

| Parameter     | Type                                                                                                 | Description                                                                                                                   |
| ------------- | ---------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md)                 | The tree node to attach the action to.                                                                                        |
| **action**    | [Action\<TTreeNode, TreeViewCancelEventArgs>](https://docs.microsoft.com/dotnet/api/system.action-2) | The action to execute before the node is selected.                                                                            |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The tree node with the action attached.

This method allows you to perform custom logic before a tree node is selected.

```csharp

treeNode.OnBeforeSelect((node, args) => { /* custom logic */ });

```

### ![](/files/lIX317sDtMTZJBi9oSIx) ShowLoader\<TTreeNode>(treeNode, value)

Sets the show loader property of the tree node.

| Parameter     | Type                                                                                 | Description                                                                                                                   |
| ------------- | ------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------- |
| **TTreeNode** |                                                                                      | The type of the tree node, which must inherit from [TreeNode](/api/wisej.web/lists-and-grids/treeview/wisej.web.treenode.md). |
| **treeNode**  | [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md) | The tree node to set the show loader property on.                                                                             |
| **value**     | [Boolean](https://docs.microsoft.com/dotnet/api/system.boolean)                      | A boolean value indicating whether the loader should be shown.                                                                |

**Returns:** [TTreeNode](/api/wisej.web.markup/extensions/wisej.web.markup.treenodeextensions.md). The modified tree node with the show loader property set.


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