SearchExpression Class (System.Web.UI.WebControls.Expressions)

The QueryExtender control provides the ability to filter data in a Web page by using the SearchExpression class. The SearchExpression class compares a specified string in a field or fields to a value that you supply. The expression performs a "starts with", "contains", or "ends with" search. You must specify values for the SearchType and the DataFields properties in order to indicate the type of search you want to perform and the data fields that you want to search. If the LINQ provider that you use in the QueryExtender control supports case sensitivity, you can use the ComparisonType property to enable or ignore case sensitivity.

The value to search can be provided by an ASP.NET control. To specify this, you set the ControlID property of the ControlParameter class in the SearchExpression object to the ID of a ASP.NET control. For example, if the value to search is entered in a text box, the ControlID property must be set to the ID of the text box control. You can use the SearchExpression class in combination with the other expressions that the QueryExtender supports, such as the RangeExpression filter. For example, you can search for product names that contain the string "tea" and a list price between 100 and 200.

The following example shows how to search the Name column in the Products table of the AdventureWorks database for products whose that start with the string that is specified in the SearchTextBox control. The result that is returned from the LinqDataSource control is displayed in a GridView control.

This code example is part of a larger example that is provided in Walkthrough: Filtering Data in a Web Page Using Declarative Syntax.

<form id="form1" runat="server">
  Search: <asp:TextBox ID="SearchTextBox" runat="server" />
  <div>
  <asp:Button ID="Button1" runat="server" Text="Search"  />
  </div>

  <asp:LinqDataSource ID="LinqDataSource1"  
       ContextTypeName="AdventureWorksDataContext"  
       TableName="Products" runat="server"> 
  </asp:LinqDataSource>

  <asp:QueryExtender runat="server" 
       TargetControlID="LinqDataSource1">
    <asp:SearchExpression SearchType="StartsWith" DataFields="Name" >
      <asp:ControlParameter ControlID="SearchTextBox" />
    </asp:SearchExpression>
  </asp:QueryExtender>

  <asp:GridView ID="GridView1" runat="server"  
      DataSourceID="LinqDataSource1" AllowPaging="True" >
  </asp:GridView>
</form>

.NET Framework

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

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