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DataGrid.AllowSorting Property

  • Reference

Definition

Namespace:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Gets or sets a value that indicates whether sorting is enabled.

C# 
public virtual bool AllowSorting { get; set; }

Property Value

Boolean

true if sorting is enabled; otherwise, false. The default value is false.

Examples

The following code example demonstrates how to use the AllowSorting property to enable sorting.

ASP.NET (C#) 
<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
 
 <!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" >
 <script language="C#" runat="server">
    
    string SortExpression;
 
    ICollection CreateDataSource() 
    {
       DataTable dt = new DataTable();
       DataRow dr;
       Random Rand_Num = new Random();
 
       dt.Columns.Add(new DataColumn("IntegerValue", typeof(Int32)));
       dt.Columns.Add(new DataColumn("StringValue", typeof(string)));
       dt.Columns.Add(new DataColumn("CurrencyValue", typeof(double)));
 
       for (int i = 0; i < 15; i++) 
       {
          dr = dt.NewRow();
 
          dr[0] = i;
          dr[1] = "Item " + i.ToString();
          dr[2] = 1.23 * Rand_Num.Next(1, 15);
 
          dt.Rows.Add(dr);
       }
 
       DataView dv = new DataView(dt);
       dv.Sort=SortExpression;
       return dv;
    }
 
    void Page_Load(Object sender, EventArgs e) 
    {
 
       if (!IsPostBack) 
       {
 
          if (SortExpression == "")
             SortExpression = "IntegerValue";      
          ItemsGrid.DataSource = CreateDataSource();
          ItemsGrid.DataBind();
       }
 
    }
 
    void Sort_Grid(Object sender, DataGridSortCommandEventArgs e) 
    {
       SortExpression = e.SortExpression.ToString();
       ItemsGrid.DataSource = CreateDataSource();
       ItemsGrid.DataBind();
    }
 
 </script>
 
 <head runat="server">
    <title>DataGrid Sorting Example</title>
</head>
<body>
 
    <form id="form1" runat="server">
 
       <h3>DataGrid Sorting Example</h3>
 
       <asp:DataGrid id="ItemsGrid" runat="server"
            BorderColor="black"
            BorderWidth="1"
            CellPadding="3"
            AllowSorting="true"
            OnSortCommand="Sort_Grid"
            HeaderStyle-BackColor="#00aaaa"
            AutoGenerateColumns="true"/>
 
    </form>
 
 </body>
 </html>
ASP.NET (C#) 
<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
    ICollection CreateDataSource()
    {
        // Create a Random object to mix up the 
        // order of items in the sample data.
        Random randNum = new Random();

        // Create sample data for the DataGrid control.
        DataTable dt = new DataTable();

        // Define the columns of the table.
        dt.Columns.Add(new DataColumn("IntegerValue", typeof(Int32)));
        dt.Columns.Add(new DataColumn("StringValue", typeof(String)));
        dt.Columns.Add(new DataColumn("CurrencyValue", typeof(Double)));

        // Populate the table with sample values.
        for (int i = 0; i <= 8; i++)
        {
            DataRow dr = dt.NewRow();
            dr[0] = i;
            dr[1] = "Item " + randNum.Next(1, 15).ToString();
            dr[2] = 1.23 * randNum.Next(1, 15);
            dt.Rows.Add(dr);
        }

        // To persist the data source between posts to the server,
        // store it in session state.  
        Session["Source"] = dt;
        DataView dv = new DataView(dt);
        return dv;
    }

    void Page_Load(Object sender, EventArgs e)
    {
        // Load sample data only once, when the page is first loaded.
        if (!IsPostBack)
        {
            ItemsGrid.DataSource = CreateDataSource();
            ItemsGrid.DataBind();
        }
    }

    void Sort_Grid(Object sender, DataGridSortCommandEventArgs e)
    {
        // Retrieve the data source from session state.
        DataTable dt = (DataTable)Session["Source"];

        // Create a DataView from the DataTable.
        DataView dv = new DataView(dt);

        // The DataView provides an easy way to sort. Simply set the
        // Sort property with the name of the field to sort by.
        dv.Sort = e.SortExpression;

        // Rebind the data source and specify that it should be sorted
        // by the field specified in the SortExpression property.
        ItemsGrid.DataSource = dv;
        ItemsGrid.DataBind();
    }

    void Check_Change(Object sender, EventArgs e)
    {
        // Allow or prevent sorting depending on the user's selection.
        ItemsGrid.AllowSorting = AllowSortingCheckBox.Checked;

        // After changing the property, rebind the data to
        // refresh the DataGrid control.

        // Retrieve the data source from session state.
        DataTable dt = (DataTable)Session["Source"];

        // Create a DataView from the DataTable.
        DataView dv = new DataView(dt);

        // Rebind the data source.
        ItemsGrid.DataSource = dv;
        ItemsGrid.DataBind();
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>
        ExtractTemplateRows Example
    </title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      <h3>DataGrid AllowSorting Example</h3>

      <p>Select whether to allow sorting in the DataGrid control.<br />
      <asp:CheckBox id="AllowSortingCheckBox"
           Text="Allow sorting"
           AutoPostBack="True"
           Checked="True"
           OnCheckedChanged="Check_Change"
           runat="server"/></p>
      <hr />
 
      <b>Product List</b>
      <asp:DataGrid id="ItemsGrid"
           BorderColor="black"
           BorderWidth="1"
           CellPadding="3"
           OnSortCommand="Sort_Grid"
           UseAccessibleHeader="true"
           AutoGenerateColumns="False"
           AllowSorting="True"
           runat="server">

         <HeaderStyle BackColor="#00aaaa" />
         <Columns>
            <asp:BoundColumn DataField="IntegerValue" 
                 SortExpression="IntegerValue"
                 HeaderText="Item"/>

            <asp:BoundColumn DataField="StringValue"
                 SortExpression="StringValue" 
                 HeaderText="Description"/>

            <asp:BoundColumn DataField="CurrencyValue" 
                 HeaderText="Price"
                 SortExpression="CurrencyValue"
                 DataFormatString="{0:c}">

               <ItemStyle HorizontalAlign="Right">
               </ItemStyle>
            </asp:BoundColumn>
         </Columns> 
      </asp:DataGrid>
 
   </div>
   </form>
</body>
</html>

Remarks

When sorting is enabled, LinkButton controls are rendered in the heading section of each column where the SortExpression property is set. These LinkButton controls allow you to sort the DataGrid control by the selected column. The only exception is when you use a TemplateColumn column type with the HeaderTemplate property set. In this case, you must provide a Button control in the HeaderTemplate of the column.

The SortCommand event is raised when one of the LinkButton controls is clicked. It is up to you to provide code for the event handler. The typical logic for the handler is to sort the list, and then rebind the data to the DataGrid control.

Applies to

Product Versions
.NET Framework 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1

See also