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DataGrid.OnItemCommand Method

Raises the ItemCommand event. This allows you to provide a custom handler for the event.

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

'Declaration
Protected Overridable Sub OnItemCommand ( _
	e As DataGridCommandEventArgs _
)

Use the OnItemCommand method to provide a custom handler for the ItemCommand event.

The ItemCommand event is raised when any button is clicked in the DataGrid control. This event is commonly used to handle buttons controls with a custom CommandName value, such as Add, in the DataGrid control.

Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.

Notes to Inheritors

When overriding OnItemCommand in a derived class, be sure to call the base class's OnItemCommand method.

For more information about handling events, see Consuming Events.

The following code example demonstrates how to specify and code a handler for the ItemCommand event to add or remove an item from a shopping cart.


<%@ 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 xmlns="http://www.w3.org/1999/xhtml" >
   <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="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 xmlns="http://www.w3.org/1999/xhtml" >
   <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

         ' Manually register the event-handling methods.
         AddHandler ItemsGrid.EditCommand, AddressOf ItemsGrid_Edit
         AddHandler ItemsGrid.CancelCommand, AddressOf ItemsGrid_Cancel
         AddHandler ItemsGrid.UpdateCommand, AddressOf ItemsGrid_Update
         AddHandler ItemsGrid.ItemCommand, AddressOf ItemsGrid_Command

      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. Make 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"
           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

Supported in: 4.5, 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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