EditCommandColumn Class (System.Web.UI.WebControls)

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Microsoft Visual Studio 2008/.NET Framework 3.5

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.NET Framework Class Library

EditCommandColumn Class

A special column type for the DataGrid control that contains the Edit buttons for editing data items in each row.

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

Syntax

Visual Basic (Declaration)

<AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level := AspNetHostingPermissionLevel.Minimal)> _
<AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level := AspNetHostingPermissionLevel.Minimal)> _
Public Class EditCommandColumn _
    Inherits DataGridColumn

Visual Basic (Usage)

Dim instance As EditCommandColumn

[AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal)]
public class EditCommandColumn : DataGridColumn

Visual C++

[AspNetHostingPermissionAttribute(SecurityAction::LinkDemand, Level = AspNetHostingPermissionLevel::Minimal)]
[AspNetHostingPermissionAttribute(SecurityAction::InheritanceDemand, Level = AspNetHostingPermissionLevel::Minimal)]
public ref class EditCommandColumn : public DataGridColumn

JScript

public class EditCommandColumn extends DataGridColumn

Remarks

Use the EditCommandColumn class to create a special column for the DataGrid control that contains the Edit, Update, and Cancel buttons for each data row in the grid. These buttons allow you to edit the values of a row in the DataGrid control.

If no row is selected, an Edit button displays in the EditCommandColumn object for each data row in the DataGrid control. When the Edit button for an item is clicked, the EditCommand event is raised and the Edit button is replaced with the Update and Cancel buttons. You need to provide code to handle the EditCommand event. A typical event handler sets the EditItemIndex property to the selected row, and then rebinds the data to the DataGrid control.

Note:
You must provide values for the CancelText, EditText, and UpdateText properties. Otherwise, the associated buttons will not appear in the EditCommandColumn.

The buttons in the EditCommandColumn can be set to display as hyperlinks or push buttons by setting the ButtonType property.

Clicking the Update or Cancel button raises the UpdateCommand or CancelCommand event, respectively. You need to provide code to handle these events.

A typical handler for the UpdateCommand event updates the data, sets the EditItemIndex property to -1 (to deselect the item), and then rebinds the data to the DataGrid control.

A typical handler for the CancelCommand event sets the EditItemIndex property to -1 (to deselect the item), and then rebinds the data to the DataGrid control.

Caution:
The EditCommandColumn object can be used to display user input, which might include malicious client script. Check any information that is sent from a client for executable script, SQL statements, or other code before displaying it in your application. You can use validation controls to verify user input before displaying the input text in a DataGrid control. ASP.NET provides an input request validation feature to block script and HTML in user input. For more information, see Securing Standard Controls, How to: Protect Against Script Exploits in a Web Application by Applying HTML Encoding to Strings, and Validating User Input in ASP.NET Web Pages.

Caution:

The EditCommandColumn object can be used to display user input, which might include malicious client script. Check any information that is sent from a client for executable script, SQL statements, or other code before displaying it in your application. You can use validation controls to verify user input before displaying the input text in a DataGrid control. ASP.NET provides an input request validation feature to block script and HTML in user input. For more information, see Securing Standard Controls, How to: Protect Against Script Exploits in a Web Application by Applying HTML Encoding to Strings, and Validating User Input in ASP.NET Web Pages.

By default, page validation is performed when an Update button in the EditCommandColumn control is clicked. Page validation determines whether the input controls that are associated with a validation control on the page all pass the validation rules that are specified by the validation control. To prevent page validation from occurring, set the CausesValidation property to false.

Examples

The following code example demonstrates how to add an EditCommandColumn object to a DataGrid control.

Visual Basic

<%@ Page Language="VB" 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  >
   <script runat="server">

      ' The Cart and CartView objects temporarily store the data source
      ' for the DataGrid control while the page is being processed.
      Dim Cart As DataTable = New DataTable()
      Dim CartView As DataView    

      Sub Page_Load(sender As Object, e As EventArgs) 

         ' With a database, use an select query to retrieve the data. Because 
         ' the data source in this example is an in-memory DataTable, retrieve
         ' the data from session state if it exists; otherwise create the data
         ' source.
         GetSource()

         ' The DataGrid control maintains state between posts to the server;
         ' it only needs to be bound to a data source the first time the page
         ' is loaded or when the data source is updated.
         If Not IsPostBack Then

            BindGrid()

         End If

      End Sub

      Sub ItemsGrid_Edit(sender As Object, e As DataGridCommandEventArgs) 

         ' Set the EditItemIndex property to the index of the item clicked 
         ' in the DataGrid control to enable editing for that item. Be sure
         ' to rebind the DateGrid to the data source to refresh the control.
         ItemsGrid.EditItemIndex = e.Item.ItemIndex
         BindGrid()

      End Sub

      Sub ItemsGrid_Cancel(sender As Object, e As DataGridCommandEventArgs) 

         ' Set the EditItemIndex property to -1 to exit editing mode.
         ' Be sure to rebind the DateGrid to the data source to refresh
         ' the control.
         ItemsGrid.EditItemIndex = -1
         BindGrid()

      End Sub

      Sub ItemsGrid_Update(sender As Object, e As DataGridCommandEventArgs) 

         ' Retrieve the text boxes that contain the values to update.
         ' For bound columns, the edited value is stored in a TextBox.
         ' The TextBox is the 0th control in a cell's Controls collection.
         ' Each cell in the Cells collection of a DataGrid item represents
         ' a column in the DataGrid control.
         Dim qtyText As TextBox = CType(e.Item.Cells(3).Controls(0), TextBox)
         Dim priceText As TextBox = CType(e.Item.Cells(4).Controls(0), TextBox)

         ' Retrieve the updated values.
         Dim item As String = e.Item.Cells(2).Text
         Dim qty As String = qtyText.Text
         Dim price As String = priceText.Text

         Dim dr As DataRow

         ' With a database, use an update command to update the data. 
         ' Because the data source in this example is an in-memory 
         ' DataTable, delete the old row and replace it with a new one.

         ' Remove the old entry and clear the row filter.
         CartView.RowFilter = "Item='" & item & "'"
         If CartView.Count > 0 Then

            CartView.Delete(0)

         End If 
         CartView.RowFilter = ""

         ' ***************************************************************
         ' Insert data validation code here. Be sure to validate the
         ' values entered by the user before converting to the appropriate
         ' data types and updating the data source.
         ' ***************************************************************

         ' Add the new entry.
         dr = Cart.NewRow()
         dr(0) = Convert.ToInt32(qty)
         dr(1) = item

         ' If necessary, remove the '$' character from the price before 
         ' converting it to a Double.
         If price.Chars(0) = "$" Then

            dr(2) = Convert.ToDouble(price.Substring(1))

         Else

            dr(2) = Convert.ToDouble(price)

         End If

         Cart.Rows.Add(dr)

         ' Set the EditItemIndex property to -1 to exit editing mode.
         ' Be sure to rebind the DateGrid to the data source to refresh
         ' the control.
         ItemsGrid.EditItemIndex = -1
         BindGrid()

      End Sub

      Sub BindGrid() 

         ' Set the data source and bind to the Data Grid control.
         ItemsGrid.DataSource = CartView
         ItemsGrid.DataBind()

      End Sub

      Sub GetSource()

         ' For this example, the data source is a DataTable that is stored
         ' in session state. If the data source does not exist, create it;
         ' otherwise, load the data.
         If Session("ShoppingCart") Is Nothing Then 

            ' Create the sample data.
            Dim dr As DataRow  

            ' Define the columns of the table.
            Cart.Columns.Add(new DataColumn("Qty", GetType(Int32)))
            Cart.Columns.Add(new DataColumn("Item", GetType(String)))
            Cart.Columns.Add(new DataColumn("Price", GetType(Double)))

            ' Store the table in session state to persist its values
            ' between posts to the server.
            Session("ShoppingCart") = Cart

            ' Populate the DataTable with sample data.
            Dim i As Integer

            For i = 1 To 9 

               dr = Cart.NewRow()
               If (i Mod 2) <> 0 Then

                  dr(0) = 2

               Else

                  dr(0) = 1

               End If

               dr(1) = "Item " & i.ToString()
               dr(2) = (1.23 * (i + 1))
               Cart.Rows.Add(dr)

            Next i

         Else

            ' Retrieve the sample data from session state.
            Cart = CType(Session("ShoppingCart"), DataTable)

         End If         

         ' Create a DataView and specify the field to sort by.
         CartView = New DataView(Cart)
         CartView.Sort="Item"

         Return

      End Sub

      Sub ItemsGrid_Command(sender As Object, e As DataGridCommandEventArgs)

         Select (CType(e.CommandSource, LinkButton)).CommandName

            Case "Delete"
               DeleteItem(e)

            ' Add other cases here, if there are multiple ButtonColumns in 
            ' the DataGrid control.

            Case Else
               ' Do nothing.

         End Select

      End Sub

      Sub DeleteItem(e As DataGridCommandEventArgs)

         ' e.Item is the table row where the command is raised. For bound 
         ' columns, the value is stored in the Text property of a TableCell.
         Dim itemCell As TableCell = e.Item.Cells(2)
         Dim item As String = itemCell.Text

         ' Remove the selected item from the data source.         
         CartView.RowFilter = "Item='" & item + "'"
         If CartView.Count > 0 Then 

            CartView.Delete(0)

         End If

         CartView.RowFilter = ""

         ' Rebind the data source to refresh the DataGrid control.
         BindGrid()

      End Sub

   </script>

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

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

      <h3>DataGrid Editing Example</h3>

      <asp:DataGrid id="ItemsGrid"
           BorderColor="black"
           BorderWidth="1"
           CellPadding="3"
           OnEditCommand="ItemsGrid_Edit"
           OnCancelCommand="ItemsGrid_Cancel"
           OnUpdateCommand="ItemsGrid_Update"
           OnItemCommand="ItemsGrid_Command"
           AutoGenerateColumns="false"
           runat="server">

         <HeaderStyle BackColor="#aaaadd">
         </HeaderStyle>

         <Columns>

            <asp:EditCommandColumn
                 EditText="Edit"
                 CancelText="Cancel"
                 UpdateText="Update" 
                 HeaderText="Edit item">

               <ItemStyle Wrap="False">
               </ItemStyle>

               <HeaderStyle Wrap="False">
               </HeaderStyle>

            </asp:EditCommandColumn>

            <asp:ButtonColumn 
                 HeaderText="Delete item" 
                 ButtonType="LinkButton" 
                 Text="Delete" 
                 CommandName="Delete"/>  

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

            <asp:BoundColumn HeaderText="Quantity" 
                 DataField="Qty"/>

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

         </Columns>

      </asp:DataGrid>

   </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  >
   <script runat="server">

      // The Cart and CartView objects temporarily store the data source
      // for the DataGrid control while the page is being processed.
      DataTable Cart = new DataTable();
      DataView CartView;   

      void Page_Load(Object sender, EventArgs e) 
      {

         // With a database, use an select query to retrieve the data. Because 
         // the data source in this example is an in-memory DataTable, retrieve
         // the data from session state if it exists; otherwise, create the data
         // source.
         GetSource();

         // The DataGrid control maintains state between posts to the server;
         // it only needs to be bound to a data source the first time the page
         // is loaded or when the data source is updated.
         if (!IsPostBack)
         {

            BindGrid();

         }

      }

      void ItemsGrid_Edit(Object sender, DataGridCommandEventArgs e) 
      {

         // Set the EditItemIndex property to the index of the item clicked 
         // in the DataGrid control to enable editing for that item. Be sure
         // to rebind the DateGrid to the data source to refresh the control.
         ItemsGrid.EditItemIndex = e.Item.ItemIndex;
         BindGrid();

      }

      void ItemsGrid_Cancel(Object sender, DataGridCommandEventArgs e) 
      {

         // Set the EditItemIndex property to -1 to exit editing mode. 
         // Be sure to rebind the DateGrid to the data source to refresh
         // the control.
         ItemsGrid.EditItemIndex = -1;
         BindGrid();

      }

      void ItemsGrid_Update(Object sender, DataGridCommandEventArgs e) 
      {

         // Retrieve the text boxes that contain the values to update.
         // For bound columns, the edited value is stored in a TextBox.
         // The TextBox is the 0th control in a cell's Controls collection.
         // Each cell in the Cells collection of a DataGrid item represents
         // a column in the DataGrid control.
         TextBox qtyText = (TextBox)e.Item.Cells[3].Controls[0];
         TextBox priceText = (TextBox)e.Item.Cells[4].Controls[0];

         // Retrieve the updated values.
         String item = e.Item.Cells[2].Text;
         String qty = qtyText.Text;
         String price = priceText.Text;

         DataRow dr;

         // With a database, use an update command to update the data. 
         // Because the data source in this example is an in-memory 
         // DataTable, delete the old row and replace it with a new one.

         // Remove the old entry and clear the row filter.
         CartView.RowFilter = "Item='" + item + "'";
         if (CartView.Count > 0)
         {
            CartView.Delete(0);
         }
         CartView.RowFilter = "";

         // ***************************************************************
         // Insert data validation code here. Be sure to validate the
         // values entered by the user before converting to the appropriate
         // data types and updating the data source.
         // ***************************************************************

         // Add the new entry.
         dr = Cart.NewRow();
         dr[0] = Convert.ToInt32(qty);
         dr[1] = item;

         // If necessary, remove the '$' character from the price before 
         // converting it to a Double.
         if(price[0] == '$')
         {
            dr[2] = Convert.ToDouble(price.Substring(1));
         }
         else
         {
            dr[2] = Convert.ToDouble(price);
         }

         Cart.Rows.Add(dr);

         // Set the EditItemIndex property to -1 to exit editing mode. 
         // Be sure to rebind the DateGrid to the data source to refresh
         // the control.
         ItemsGrid.EditItemIndex = -1;
         BindGrid();

      }

      void BindGrid() 
      {

         // Set the data source and bind to the Data Grid control.
         ItemsGrid.DataSource = CartView;
         ItemsGrid.DataBind();

      }

      void GetSource()
      {

         // For this example, the data source is a DataTable that is stored
         // in session state. If the data source does not exist, create it;
         //  otherwise, load the data.
         if (Session["ShoppingCart"] == null) 
         {     

            // Create the sample data.
            DataRow dr;  

            // Define the columns of the table.
            Cart.Columns.Add(new DataColumn("Qty", typeof(Int32)));
            Cart.Columns.Add(new DataColumn("Item", typeof(String)));
            Cart.Columns.Add(new DataColumn("Price", typeof(Double)));

            // Store the table in session state to persist its values 
            // between posts to the server.
            Session["ShoppingCart"] = Cart;

            // Populate the DataTable with sample data.
            for (int i = 1; i <= 9; i++) 
            {
               dr = Cart.NewRow();
               if (i % 2 != 0)
               {
                  dr[0] = 2;
               }
               else
               {
                  dr[0] = 1;
               }
               dr[1] = "Item " + i.ToString();
               dr[2] = (1.23 * (i + 1));
               Cart.Rows.Add(dr);
            }

         } 

         else
         {

            // Retrieve the sample data from session state.
            Cart = (DataTable)Session["ShoppingCart"];

         }         

         // Create a DataView and specify the field to sort by.
         CartView = new DataView(Cart);
         CartView.Sort="Item";

         return;

      }

      void ItemsGrid_Command(Object sender, DataGridCommandEventArgs e)
      {

         switch(((LinkButton)e.CommandSource).CommandName)
         {

            case "Delete":
               DeleteItem(e);
               break;

            // Add other cases here, if there are multiple ButtonColumns in 
            // the DataGrid control.

            default:
               // Do nothing.
               break;

         }

      }

      void DeleteItem(DataGridCommandEventArgs e)
      {

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

         // Remove the selected item from the data source.         
         CartView.RowFilter = "Item='" + item + "'";
         if (CartView.Count > 0) 
         {     
            CartView.Delete(0);
         }
         CartView.RowFilter = "";

         // Rebind the data source to refresh the DataGrid control.
         BindGrid();

      }

   </script>

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

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

      <h3>DataGrid Editing Example</h3>

      <asp:DataGrid id="ItemsGrid"
           BorderColor="black"
           BorderWidth="1"
           CellPadding="3"
           OnEditCommand="ItemsGrid_Edit"
           OnCancelCommand="ItemsGrid_Cancel"
           OnUpdateCommand="ItemsGrid_Update"
           OnItemCommand="ItemsGrid_Command"
           AutoGenerateColumns="false"
           runat="server">

         <HeaderStyle BackColor="#aaaadd">
         </HeaderStyle>

         <Columns>

            <asp:EditCommandColumn
                 EditText="Edit"
                 CancelText="Cancel"
                 UpdateText="Update" 
                 HeaderText="Edit item">

               <ItemStyle Wrap="False">
               </ItemStyle>

               <HeaderStyle Wrap="False">
               </HeaderStyle>

            </asp:EditCommandColumn>

            <asp:ButtonColumn 
                 HeaderText="Delete item" 
                 ButtonType="LinkButton" 
                 Text="Delete" 
                 CommandName="Delete"/>  

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

            <asp:BoundColumn HeaderText="Quantity" 
                 DataField="Qty"/>

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

         </Columns>

      </asp:DataGrid>

   </form>

</body>
</html>

.NET Framework Security

AspNetHostingPermission
for operating in a hosted environment. Demand value: LinkDemand; Permission value: Minimal.
AspNetHostingPermission
for operating in a hosted environment. Demand value: InheritanceDemand; Permission value: Minimal.

Inheritance Hierarchy

System..::.Object
System.Web.UI.WebControls..::.DataGridColumn
System.Web.UI.WebControls..::.EditCommandColumn

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

Version Information

.NET Framework

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

Reference

EditCommandColumn Members

System.Web.UI.WebControls Namespace