If the number of characters in a URL of a node is larger than that number, expanding that node will fail and no exception is thrown.īy default, clicking a node that is in selection mode posts the page back to the server and raises the SelectedNodeChanged event. For example, Microsoft Internet Explorer 6.0 has a URL character limit of 2067 characters that it posts. Some Internet browsers have a limitation that can affect the performance of the TreeView control. To put a node into selection mode, set the node's NavigateUrl property to an empty string. To put a node into navigation mode, set the node's NavigateUrl property to a value other than an empty string (""). The text of a node in the TreeView control can be in one of two modes: selection mode or navigation mode. This image is displayed next to the node text. You can display an image in a node by setting the ImageUrl property. When a check box is displayed, use the Checked property to determine whether the check box is selected. You can selectively override the check box of an individual node by setting the node's ShowCheckBox property. When the ShowCheckBoxes property is set to a value other than TreeNodeType.Node, check boxes are displayed next to the specified node type. To display a check box next to a node, set the ShowCheckBoxes property of the TreeView class. The expansion node indicator icons can even be hidden entirely by setting the ShowExpandCollapse property of the TreeView class to false. You can specify a custom image for the expandable, collapsible, and non-expandable node indicators by setting the ExpandImageUrl, CollapseImageUrl, and NoExpandImageUrl properties of the TreeView class. In this scenario, if the user clicks a node that has a duplicate value, the node that appears first in the TreeView control is selected.Ī TreeNode object is made up of the following four user interface (UI) elements, which can be customized or hidden:Īn expansion node indicator icon used to show whether the node is expanded, collapsed, or non-expandable.Īn optional check box associated with the node. Nodes at the same level must each have a unique value for the Value property the TreeView control cannot distinguish between different nodes at the same level that have the same value. The ValuePath property indicates the node's position relative to the root node. A node also stores the path from the node to its root node in the ValuePath property.
The value of the Text property is displayed in the TreeView control, and the Value property is used to store any additional data about the node, such as data used for handling postback events. This is useful when you want to display item listings without displaying a single main root node, as in a list of product categories.Ī node primarily stores data in two properties, the Text property and the Value property. Several visual and behavioral properties of nodes are determined by whether a node is a root, parent, or leaf node.Īlthough a typical tree has only one root node, the TreeView control allows you to add multiple root nodes to your tree structure. A node can be both a parent and a child, but root, parent, and leaf nodes are mutually exclusive. A node that is not contained by any other node but is the ancestor to all the other nodes is the root node. A node that has no child nodes is called a leaf node. A node that is contained by another node is called a child node. A node that contains other nodes is called a parent node.
Each entry in the tree is called a node and is represented by a TreeNode object. The TreeView control is made up of nodes. This example is used within the frameset of the previous example to display a table of contents.
TREEVIEW IN ASP NET HOW TO
The following code example demonstrates how to use declarative syntax to create TreeNode objects in the TreeView control. The following code example demonstrates how to set up the frames for the next code example.
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