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GridView.SortExpression Property

Note: This property is new in the .NET Framework version 2.0.

Gets the sort expression associated with the column or columns being sorted.

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

public virtual string SortExpression { get; }
/** @property */
public String get_SortExpression ()

public function get SortExpression () : String

Property Value

The sort expression associated with the column or columns being sorted.

Use the SortExpression property to determine the sort expression associated with the column or columns being sorted.

NoteNote

The GridView control has a built-in sorting feature that automatically sets this property. This property is typically used only when you need to programmatically determine the column or columns being sorted or when you are adding your own custom sorting functionality to a GridView control.

When multiple columns are sorted, this property contains a comma-separated list of the fields by which to sort.

The following code example demonstrates how to use the SortExpression property to determine the name of the column being sorted.


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

<script runat="server">

  void CustomersGridView_RowCreated(Object sender, GridViewRowEventArgs e)
  {
    
    // Use the RowType property to determine whether the 
    // row being created is the header row. 
    if (e.Row.RowType == DataControlRowType.Header)
    {
      // Call the GetSortColumnIndex helper method to determine
      // the index of the column being sorted.
      int sortColumnIndex = GetSortColumnIndex();
      
      if (sortColumnIndex != -1)
      {
        // Call the AddSortImage helper method to add
        // a sort direction image to the appropriate
        // column header. 
        AddSortImage(sortColumnIndex, e.Row);
      }
    }
  }

  // This is a helper method used to determine the index of the
  // column being sorted. If no column is being sorted, -1 is returned.
  int GetSortColumnIndex()
  {

    // Iterate through the Columns collection to determine the index
    // of the column being sorted.
    foreach (DataControlField field in CustomersGridView.Columns)
    {
      if (field.SortExpression == CustomersGridView.SortExpression)
      {
        return CustomersGridView.Columns.IndexOf(field);
      }
    }

    return -1;
  }

  // This is a helper method used to add a sort direction
  // image to the header of the column being sorted.
  void AddSortImage(int columnIndex, GridViewRow headerRow)
  {
    
    // Create the sorting image based on the sort direction.
    Image sortImage = new Image();
    if (CustomersGridView.SortDirection == SortDirection.Ascending)
    {
      sortImage.ImageUrl = "~/Images/Ascending.jpg";
      sortImage.AlternateText = "Ascending Order";
    }
    else
    {
      sortImage.ImageUrl = "~/Images/Descending.jpg";
      sortImage.AlternateText = "Descending Order";
    }

    // Add the image to the appropriate header cell.
    headerRow.Cells[columnIndex].Controls.Add(sortImage);
    
  }
    
</script>

<html>
  <body>
    <form runat="server">
        
      <h3>GridView AllowSorting Example</h3>

      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSource" 
        autogeneratecolumns="false"
        emptydatatext="No data available." 
        allowsorting="true"
        onrowcreated="CustomersGridView_RowCreated"
        runat="server">
        
        <columns>
          <asp:boundfield datafield="CustomerID"
            headertext="Customer ID"
            headerstyle-wrap="false" 
            sortexpression="CustomerID"/>
          <asp:boundfield datafield="CompanyName"
            headertext="CompanyName"
            headerstyle-wrap="false"
            sortexpression="CompanyName"/>
          <asp:boundfield datafield="Address"
            headertext="Address"
            headerstyle-wrap="false"
            sortexpression="Address"/>
          <asp:boundfield datafield="City"
            headertext="City"
            headerstyle-wrap="false"
            sortexpression="City"/>
          <asp:boundfield datafield="PostalCode"
            headertext="Postal Code"
            headerstyle-wrap="false"
            sortexpression="PostalCode" />
          <asp:boundfield datafield="Country"
            headertext="Country"
            headerstyle-wrap="false"
            sortexpression="Country"/>         
        </columns>
                
      </asp:gridview>
            
      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the Web.config file.                            -->
      <asp:sqldatasource id="CustomersSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>
        
    </form>
  </body>
</html>


Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0

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