TreeNodeBinding.ValueField Property

 

Gets or sets the name of the field from the data source to bind to the Value property of a TreeNode object to which the TreeNodeBinding object is applied.

Namespace:   System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

[TypeConverterAttribute("System.Web.UI.Design.DataSourceViewSchemaConverter, System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a")]
public string ValueField { get; set; }

Property Value

Type: System.String

The name of the field to bind to the Value property of a TreeNode object to which the TreeNodeBinding object is applied. The default is an empty string (""), which indicates that the ValueField property is not set.

When the TreeView control is bound to a data source, use the ValueField property to specify the field name to bind to the Value property of a TreeNode object. This binding relationship affects all TreeNode objects to which the TreeNodeBinding object is applied. The Value property is used to supplement the Text property by storing any additional data associated with the node to which the TreeNodeBinding object is applied. This value is not displayed in the control and is commonly used to store data for handling postback events.

System_CAPS_noteNote

You can selectively override the ValueField property by setting the Value property of each node directly.

Instead of using the ValueField property to bind the Value property of a TreeNode object to an field, you can set the Value property to a fixed value by setting the Value property.

System_CAPS_noteNote

If the data source contains multiple fields, you must first set the Depth or DataMember property, or both properties in order to bind to the appropriate field.

The value of this property is stored in view state.

This section contains two code examples. The first code example demonstrates how to use the ValueField property to specify which attribute of an XML element to bind to the Value property of a TreeNode object to which the TreeNodeBinding object is applied. The second code example provides sample XML data for the first code example.

The following example demonstrates how to use the ValueField property to specify which attribute of an XML element to bind to the Value property of a TreeNode object to which the TreeNodeBinding object is applied. For this example to work correctly, you must copy the sample XML data, provided after this code example, to a file named Booklist.xml.


<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>TreeViewBinding Example</title>
</head>
<body>
    <form id="form1" runat="server">

      <h3>TreeViewBinding Example</h3>

      <!-- Set the TextField, ImageUrlField, NavigateUrlField, -->
      <!-- ValueField, and ToolTipField properties of a    -->
      <!-- TreeNodeBinding object declaratively.         -->
      <asp:TreeView id="BookTreeView" 
        DataSourceID="BookXmlDataSource"
        Target="_blank" 
        runat="server">

        <DataBindings>
          <asp:TreeNodeBinding DataMember="Books" 
            Depth="0" 
            TextField="Text"/>
          <asp:TreeNodeBinding DataMember="Book" 
            Depth="1" 
            TextField="Text" 
            ImageUrlField="Image"
            ImageToolTipField="ImageToolTip" 
            NavigateUrlField="Nav" 
            ValueField="Value" 
            ToolTipField="Tip"/>
          <asp:TreeNodeBinding DataMember="Description" 
            Depth="2" 
            TextField="Text"/>
          <asp:TreeNodeBinding DataMember="Price" 
            Depth="2" 
            TextField="Value"/>
        </DataBindings>

      </asp:TreeView>

      <asp:XmlDataSource id="BookXmlDataSource"  
        DataFile="Booklist.xml"
        runat="server">
      </asp:XmlDataSource>

    </form>
  </body>
</html>

The following code example provides sample XML data for the preceding code example.

<Books Text="Books List">
    <Book Text="Book Title One"
        Value="1" 
        Image="Bookimage1.jpg"
        ImageToolTip="Book 1 Photo" 
        Nav="http://www.microsoft.com"
        Tip="Book Title 1">
        <Description Text="Book Description">
        </Description>
        <Price Value="$1.99">
        </Price>
        <Author Text="Author Name"
            Value="LastName" 
            Image="Authorimage1.jpg" 
            Nav="http://www.microsoft.com"
            Tip="Author Name">
        </Author>
    </Book>
    <Book Text="Book Title Two"
        Value="2" 
        Image="Bookimage2.jpg"
        ImageToolTip="Book 2 Photo" 
        Nav="http://www.microsoft.com"
        Tip="Click Me">
        <Description Text="Book Description">
        </Description>
        <Price Value="$2.99">
        </Price>
        <Author Text="Author Name"
            Value="LastName" 
            Image="Authorimage2.jpg" 
            Nav="http://www.microsoft.com"
            Tip="Author Name">
        </Author>
    </Book>
</Books>

.NET Framework
Available since 2.0
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