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DataGrid.Columns Property

Gets a collection of objects that represent the columns of the DataGrid control.

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

[PersistenceModeAttribute(PersistenceMode.InnerProperty)]
public virtual DataGridColumnCollection Columns { get; }

Property Value

Type: System.Web.UI.WebControls.DataGridColumnCollection
A DataGridColumnCollection object that contains a collection of objects that represent the columns of the DataGrid control.

Use this property to programmatically control the collection of columns in the DataGrid control. The Columns collection contains explicitly declared columns that get rendered in the DataGrid control.

NoteNote

Explicitly declared columns may be used in conjunction with automatically generated columns. When using both, explicitly declared columns will be rendered first, followed by the automatically generated columns. Automatically generated columns are not added to the Columns collection.

The order that the columns are displayed in the DataGrid control is controlled by the order that the columns appear in the Columns collection.

The following table shows the different column classes that derive from the DataGridColumn class and can be used in the Columns collection.

Column type

Description

BoundColumn

Displays a column bound to a field in a data source. It displays each item in the field as text. This is the default column type of the DataGrid control.

ButtonColumn

Displays a command button for each item in the column. This allows you to create a column of custom button controls, such as the Add or Remove button.

EditCommandColumn

Displays a column that contains editing commands for each item in the column.

HyperLinkColumn

Displays the contents of each item in the column as a hyperlink. The contents of the column can be bound to a field in a data source or static text.

TemplateColumn

Displays each item in the column following a specified template. This allows you to provide custom controls in the column.

NoteNote

Although you can programmatically add columns to the Columns collection, it is easier to list the columns statically and then use the Visible property to show or hide the column.

The following code example demonstrates how to use the Columns collection to dynamically add a column to the DataGrid control.

<%@ 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">

      DataTable Cart;
      DataView CartView;

      ICollection CreateDataSource() 
      {
         DataTable dt = new DataTable();
         DataRow dr;

         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 < 9; i++) 
         {
            dr = dt.NewRow();

            dr[0] = i;
            dr[1] = "Item " + i.ToString();
            dr[2] = 1.23 * (i + 1);

            dt.Rows.Add(dr);
         }

         DataView dv = new DataView(dt);
         return dv;
      } 

      void Page_Load(Object sender, EventArgs e) 
      {

         if (Session["DG4_ShoppingCart"] == null) 
         {
            Cart = new DataTable();
            Cart.Columns.Add(new DataColumn("Item", typeof(string)));
            Cart.Columns.Add(new DataColumn("Price", typeof(string)));
            Session["DG4_ShoppingCart"] = Cart;
         }
         else 
         {
            Cart = (DataTable)Session["DG4_ShoppingCart"];
         }    
         CartView = new DataView(Cart);
         ShoppingCart.DataSource = CartView;
         ShoppingCart.DataBind();

         if (!IsPostBack) 
         {
            // Load this data only once.
            ItemsGrid.DataSource= CreateDataSource();
            ItemsGrid.DataBind();
         }

      }

      void Page_Init(Object sender, EventArgs e) 
      {

         // Create a dynamic column to add to Columns collection.
         BoundColumn NumberColumn = new BoundColumn();
         NumberColumn.HeaderText="Item Number"; 
         NumberColumn.DataField="IntegerValue";

         // Add column to Columns collection.
         ItemsGrid.Columns.AddAt(2, NumberColumn);

      }

      void Grid_CartCommand(Object sender, DataGridCommandEventArgs e) {

         DataRow dr = Cart.NewRow();

         // e.Item is the table row where the command is raised.
         // For bound columns, the value is stored in the Text property of the TableCell.
         TableCell itemCell = e.Item.Cells[2];
         TableCell priceCell = e.Item.Cells[3];
         string item = itemCell.Text;
         string price = priceCell.Text;

         if (((Button)e.CommandSource).CommandName == "AddToCart") 
         {
            dr[0] = item;
            dr[1] = price;
            Cart.Rows.Add(dr);
         }
         else 
         { 

            //Remove from Cart.

            CartView.RowFilter = "Item='" + item + "'";
            if (CartView.Count > 0) 
            {    
               CartView.Delete(0);
            }
            CartView.RowFilter = "";
         }
         ShoppingCart.DataBind();

      }

   </script>

<head runat="server">
    <title>DataGrid Columns Example</title>
</head>
<body>

   <form id="form1" runat="server">

      <h3>DataGrid Columns Example</h3>

      <table cellpadding="5">
         <tr valign="top">
            <td>

               <b>Product List</b>

               <asp:DataGrid id="ItemsGrid"
                    BorderColor="black"
                    BorderWidth="1"
                    CellPadding="3"
                    AutoGenerateColumns="false"
                    OnItemCommand="Grid_CartCommand"
                    runat="server">

                  <HeaderStyle BackColor="#00aaaa">
                  </HeaderStyle>

                  <Columns>

                     <asp:ButtonColumn 
                          HeaderText="Add to cart" 
                          ButtonType="PushButton" 
                          Text="Add" 
                          CommandName="AddToCart"/>

                     <asp:ButtonColumn 
                          HeaderText="Remove from cart" 
                          ButtonType="PushButton" 
                          Text="Remove" 
                          CommandName="RemoveFromCart"/>

                     <asp:BoundColumn 
                          HeaderText="Item" 
                          DataField="StringValue"/>

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

                        <ItemStyle HorizontalAlign="right">
                        </ItemStyle>

                     </asp:BoundColumn>

                  </Columns>

               </asp:DataGrid>

            </td>
            <td>

               <b>Shopping Cart</b>

               <asp:DataGrid id="ShoppingCart" 
                    runat="server"
                    BorderColor="black"
                    BorderWidth="1"
                    GridLines="Both"
                    ShowFooter="false"
                    CellPadding="3"
                    CellSpacing="0">

                  <HeaderStyle BackColor="#00aaaa">
                  </HeaderStyle>

                </asp:DataGrid>

            </td>
         </tr>

      </table>

   </form>

</body>
</html>

<%@ 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 runat="server">

      ICollection CreateDataSource() 
      {

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

         // 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 < 5; i++) 
         {
            dr = dt.NewRow();

            dr[0] = i;
            dr[1] = "Item " + i.ToString();
            dr[2] = 1.23 * (i + 1);

            dt.Rows.Add(dr);
         }

         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 Button_Click(Object sender, EventArgs e) 
      {

         // Count the number of selected items in the DataGrid control.
         int count = 0;

         // Display the selected times.
         Message.Text = "You Selected: <br />";

         // Iterate through each item (row) in the DataGrid control and
         // determine whether it is selected.
         foreach (DataGridItem item in ItemsGrid.Items)
         {

            DetermineSelection(item, ref count);        

         }

         // If no items are selected, display the appropriate message.
         if (count == 0)
         {

            Message.Text = "No items selected";

         }

      }

      void DetermineSelection(DataGridItem item, ref int count)
      {

         // Retrieve the SelectCheckBox CheckBox control from the 
         // specified item (row) in the DataGrid control.
         CheckBox selection = (CheckBox)item.FindControl("SelectCheckBox");

         // If the item is selected, display the appropriate message and
         // increment the count of selected items.
         if (selection != null)
         {

           if (selection.Checked)
           {
              Message.Text += "- " + item.Cells[1].Text + "<br />";
              count++;
           }

         }    

      }

      void Check_Change(Object sender, EventArgs e)
      {

         // Show or hide the first column depending on the value of
         // the check box.
         if (ShowCheckBox.Checked)
         {
            ItemsGrid.Columns[0].Visible = true;
         }
         else
         {
            ItemsGrid.Columns[0].Visible = false;
         }

      }

   </script>

<head runat="server">
    <title>DataGridColumn Visible Example</title>
</head>
<body>

   <form id="form1" runat="server">

      <h3>DataGridColumn Visible Example</h3>

      Select whether to show or hide the first column.

      <br /><br />

      <b>Product List</b>

      <asp:DataGrid id="ItemsGrid"
           BorderColor="black"
           BorderWidth="1"
           CellPadding="3"
           ShowFooter="True"
           AutoGenerateColumns="False"
           runat="server">

         <HeaderStyle BackColor="#00aaaa">
         </HeaderStyle>

         <FooterStyle BackColor="#00aaaa">
         </FooterStyle>

         <Columns>

            <asp:BoundColumn DataField="IntegerValue"
                 Visible="True" 
                 HeaderText="Item"/>

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

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

               <ItemStyle HorizontalAlign="Right">
               </ItemStyle>

            </asp:BoundColumn>

            <asp:TemplateColumn HeaderText="Select Item"
                 Visible="True" >

               <ItemTemplate>

                  <asp:CheckBox id="SelectCheckBox"
                       Text="Add to Cart"
                       Checked="False"
                       runat="server"/>

               </ItemTemplate>

            </asp:TemplateColumn>

         </Columns>  

      </asp:DataGrid>

      <br /><br />

      <asp:Button id="SubmitButton"
           Text="Submit"
           OnClick = "Button_Click"
           runat="server"/>

      <br /><br />

      <asp:Label id="Message"
           runat="server"/>

      <hr />

      <asp:CheckBox id="ShowCheckBox"
           Text="Show first column"
           AutoPostBack="True"
           OnCheckedChanged="Check_Change"
           Checked="True"
           runat="server"/>

   </form>

</body>
</html>

.NET Framework

Supported in: 4.6, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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