DataGrid.OnCancelCommand(DataGridCommandEventArgs) Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Raises the CancelCommand event. This allows you to provide a custom handler for the event.
protected:
virtual void OnCancelCommand(System::Web::UI::WebControls::DataGridCommandEventArgs ^ e);protected virtual void OnCancelCommand (System.Web.UI.WebControls.DataGridCommandEventArgs e);abstract member OnCancelCommand : System.Web.UI.WebControls.DataGridCommandEventArgs -> unit
override this.OnCancelCommand : System.Web.UI.WebControls.DataGridCommandEventArgs -> unitProtected Overridable Sub OnCancelCommand (e As DataGridCommandEventArgs)Parameters
A DataGridCommandEventArgs that contains event data.
Examples
The following code example demonstrates how to specify and code a handler for the CancelCommand event to cancel edits made to an item in 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 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>
<%@ 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="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">
// 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();
}
// Manually register the event-handling methods.
ItemsGrid.EditCommand +=
new DataGridCommandEventHandler(this.ItemsGrid_Edit);
ItemsGrid.CancelCommand +=
new DataGridCommandEventHandler(this.ItemsGrid_Cancel);
ItemsGrid.UpdateCommand +=
new DataGridCommandEventHandler(this.ItemsGrid_Update);
ItemsGrid.ItemCommand +=
new DataGridCommandEventHandler(this.ItemsGrid_Command);
}
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. 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 '$' character, from the price before
// converting it to a Double.
if(price[0] == '$')
{
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>
<%@ 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>
Remarks
Use the OnCancelCommand method to provide a custom handler for the CancelCommand event.
The CancelCommand event is raised when the Cancel button is clicked for an item in 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
Text is not HTML encoded before it is displayed in the DataGrid control. This makes it possible to embed script within HTML tags in the text. If the values for the control come from user input, be sure to validate the values to reduce security vulnerabilities.
Raising an event invokes the event handler through a delegate. For more information, see Handling and Raising Events.
Notes to Inheritors
When overriding OnCancelCommand(DataGridCommandEventArgs) in a derived class, be sure to call the base class's OnCancelCommand(DataGridCommandEventArgs) method.
For more information about how to handle events, see Handling and Raising Events.
Applies to
See also
Samarbeta med oss på GitHub
Källan för det här innehållet finns på GitHub, där du även kan skapa och granska ärenden och pull-begäranden. Se vår deltagarguide för mer information.
