Check Box Support
- 3 minutes to read
ASPxTreeView allows end-users to check nodes. To enable this feature, set the ASPxTreeView.AllowCheckNodes property to true. You can disable the check box for a particular node by setting its TreeViewNode.AllowCheck property to false.
A node has two parameters that describe its check state:
- TreeViewNode.Checked property specifies whether the node is checked or not. Its value can to be equal to true or false;
- TreeViewNode.CheckState property gets the node check state. Its value can to be equal to CheckState.Checked, CheckState.Unchecked, CheckState.Indeterminate.
The CheckState property is read only. It changes automatically dependent on the node and node's child nodes Checked property values. This behavior is by design, because an indeterminate node state means that the node has checked and unchecked children. If setting this state manually was allowed, it could break the check box logic.
The correspondence table of Checked and CheckState property values is presented below.
|Appearance||Checked||CheckState||Conditions (provided the CheckNodesRecursive is set to true)|
|true||Checked||The node has been checked or all its child nodes have been checked|
|false||Unchecked||The node has been unchecked or all its child nodes have been unchecked|
|false||Indeterminate||The node has checked and unchecked child nodes|
ASPxTreeView allows you to change the appearance of all check boxes using the TreeViewStyles.NodeCheckBox property. The appearance of a particular check box can be customized via a node's TreeViewNode.CheckBoxStyle property. To customize an appearance of a focused check box use TreeViewStyles.NodeCheckBoxFocused property.
You can check/uncheck a node programmatically via the TreeViewNode.Checked property. When a node's Checked property value changes, the ASPxTreeView.CheckedChanged event occurs, allowing you to respond to this action. To obtain a node's check state, use the TreeViewNode.CheckState property.
On the client, you can handle the ASPxClientTreeView.CheckedChanged event to respond to a change of a node's Checked property value. To obtain and set a node's Checked property value, use the ASPxClientTreeViewNode.GetChecked and ASPxClientTreeViewNode.SetChecked methods respectively. To obtain a node's check state, use the ASPxClientTreeViewNode.GetCheckState method.
You can allow end-users to employ recursive node checking. When the ASPxTreeView.CheckNodesRecursive property is set to true:
- checking a parent node automatically checks all its children;
- a parent node is automatically checked if all its child nodes are checked;
- a parent node's check state is automatically set to indeterminate if it has checked and unchecked child nodes.
Take a look at this image to see how recursive node checking works.