GridViewDeleteEventHandler Делегат

Ссылка

Определение

Пространство имен:: System.Web.UI.WebControls

Сборка:: System.Web.dll

Важно!

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Представляет метод, обрабатывающий событие RowDeleting элемента управления GridView.

public delegate void GridViewDeleteEventHandler(System::Object ^ sender, GridViewDeleteEventArgs ^ e);

public delegate void GridViewDeleteEventHandler(object sender, GridViewDeleteEventArgs e);

type GridViewDeleteEventHandler = delegate of obj * GridViewDeleteEventArgs -> unit

Public Delegate Sub GridViewDeleteEventHandler(sender As Object, e As GridViewDeleteEventArgs)

Параметры

sender: Object

Источник события.

e: GridViewDeleteEventArgs

Объект GridViewDeleteEventArgs, содержащий данные события.

Примеры

В следующем примере показано, как программным способом GridViewDeleteEventHandler добавить делегат в RowDeleting событие GridView элемента управления .


<%@ Page language="C#" %>

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

  void Page_Load(Object sender, EventArgs e)
  {
        
    // Create a new GridView control.
    GridView customersGridView = new GridView();
         
    // Set the GridView control's properties.          
    customersGridView.ID = "CustomersGridView";
    customersGridView.DataSourceID = "CustomersSqlDataSource"; 
    customersGridView.AutoGenerateColumns = true;
    customersGridView.AutoGenerateDeleteButton = true;
    customersGridView.DataKeyNames = new String[] {"CustomerID"};
       
    // Programmatically register the event-handling methods.
    customersGridView.RowDeleting += new GridViewDeleteEventHandler(this.CustomersGridView_RowDeleting);
        
    // Add the GridView object to the Controls collection
    // of the PlaceHolder control.
    GridViewPlaceHolder.Controls.Add(customersGridView);
        
  }
    
  void CustomersGridView_RowDeleting(Object sender, GridViewDeleteEventArgs e)
  {

    // User the sender parameter to retrieve the GridView control
    // that raised the event.
    GridView customersGridView = (GridView)sender;
    
    // Cancel the delete operation if the user attempts to remove
    // the last record from the GridView control.
    if (customersGridView.Rows.Count <= 1)
    {
        
      e.Cancel = true;
      Message.Text = "You must keep at least one record.";
            
    }
    
  }  

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewDeleteEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewDeleteEventHandler Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"          
        runat="server"/>
                
      <br/>
      
      <asp:placeholder id="GridViewPlaceHolder"
        runat="server"/>
            
      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the Web.config file.                            -->
      <asp:sqldatasource id="CustomersSqlDataSource"  
        selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
        deletecommand="Delete from Customers where CustomerID = @CustomerID"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
        runat="server">
      </asp:sqldatasource>
      
    </form>
  </body>
</html>


<%@ Page language="VB" %>

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

  Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
            
    ' Create a new GridView control.
    Dim customersGridView As New GridView()
         
    ' Set the GridView control's properties.          
    customersGridView.ID = "CustomersGridView"
    customersGridView.DataSourceID = "CustomersSqlDataSource"
    customersGridView.AutoGenerateColumns = True
    customersGridView.AutoGenerateDeleteButton = True
    Dim keyArray() As String = {"CustomerID"}
    customersGridView.DataKeyNames = keyArray
       
    ' Programmatically register the event-handling methods.
    AddHandler customersGridView.RowDeleting, AddressOf CustomersGridView_RowDeleting
        
    ' Add the GridView object to the Controls collection
    ' of the PlaceHolder control.
    GridViewPlaceHolder.Controls.Add(customersGridView)
        
  End Sub
    
  Sub CustomersGridView_RowDeleting(ByVal sender As Object, ByVal e As GridViewDeleteEventArgs)

    ' User the sender parameter to retrieve the GridView control
    ' that raised the event.
    Dim customersGridView As GridView = CType(sender, GridView)
    
    ' Cancel the delete operation if the user attempts to remove
    ' the last record from the GridView control.
    If customersGridView.Rows.Count <= 1 Then

      e.Cancel = True
      Message.Text = "You must keep at least one record."
            
    End If
    
  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewDeleteEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewDeleteEventHandler Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"          
        runat="server"/>
                
      <br/>
      
      <asp:placeholder id="GridViewPlaceHolder"
        runat="server"/>
            
      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the Web.config file.                            -->
      <asp:sqldatasource id="CustomersSqlDataSource"  
        selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
        deletecommand="Delete from Customers where CustomerID = @CustomerID"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
        runat="server">
      </asp:sqldatasource>
      
    </form>
  </body>
</html>

В следующем примере показано, как декларативно добавить GridViewDeleteEventHandler делегат в RowDeleting событие GridView элемента управления .


<%@ Page Language="C#" %>

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

<script runat="server">

    void CustomersGridView_RowDeleting
        (Object sender, GridViewDeleteEventArgs e)
    {
        TableCell cell = CustomersGridView.Rows[e.RowIndex].Cells[2];
        if (cell.Text == "Beaver")
        {
            e.Cancel = true;
            Message.Text = "You cannot delete customer Beaver.";
        }
        else
        {
            Message.Text = "";
        }
    }  

</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>GridView RowDeleting Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <h3>
        GridView RowDeleting Example
    </h3>
    <asp:Label ID="Message" ForeColor="Red" runat="server" />
    <br />
    <asp:GridView ID="CustomersGridView" runat="server" 
        DataSourceID="CustomersSqlDataSource" 
        AutoGenerateColumns="False"
        AutoGenerateDeleteButton="True" 
        OnRowDeleting="CustomersGridView_RowDeleting"
        DataKeyNames="CustomerID,AddressID">
        <Columns>
            <asp:BoundField DataField="FirstName" 
                HeaderText="FirstName" SortExpression="FirstName" />
            <asp:BoundField DataField="LastName" HeaderText="LastName" 
                SortExpression="LastName" />
            <asp:BoundField DataField="City" HeaderText="City" 
                SortExpression="City" />
            <asp:BoundField DataField="StateProvince" HeaderText="State" 
                SortExpression="StateProvince" />
        </Columns>
    </asp:GridView>
    <asp:SqlDataSource ID="CustomersSqlDataSource" runat="server"
        SelectCommand="SELECT SalesLT.CustomerAddress.CustomerID, 
            SalesLT.CustomerAddress.AddressID, 
            SalesLT.Customer.FirstName, 
            SalesLT.Customer.LastName, 
            SalesLT.Address.City, 
            SalesLT.Address.StateProvince 
            FROM SalesLT.Customer 
            INNER JOIN SalesLT.CustomerAddress 
            ON SalesLT.Customer.CustomerID = 
                SalesLT.CustomerAddress.CustomerID 
            INNER JOIN SalesLT.Address ON SalesLT.CustomerAddress.AddressID = 
                SalesLT.Address.AddressID"
        DeleteCommand="Delete from SalesLT.CustomerAddress where CustomerID = 
            @CustomerID and AddressID = @AddressID" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>">
        <DeleteParameters>
            <asp:Parameter Name="AddressID" />
            <asp:Parameter Name="CustomerID" />
        </DeleteParameters>
    </asp:SqlDataSource>
    </form>
</body>
</html>


<%@ Page Language="VB" %>

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

<script runat="server">

    Private Sub CustomersGridView_RowDeleting _
        (ByVal sender As [Object], _
        ByVal e As GridViewDeleteEventArgs)
        Dim cell As TableCell
        cell = CustomersGridView.Rows(e.RowIndex).Cells(2)
        If cell.Text = "Beaver" Then
            e.Cancel = True
            Message.Text = "You cannot delete customer Beaver."
        Else
            Message.Text = ""
        End If
    End Sub
    
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>GridView RowDeleting Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <h3>
        GridView RowDeleting Example
    </h3>
    <asp:Label ID="Message" ForeColor="Red" runat="server" />
    <br />
    <asp:GridView ID="CustomersGridView" runat="server" 
        DataSourceID="CustomersSqlDataSource" 
        AutoGenerateColumns="False"
        AutoGenerateDeleteButton="True" 
        OnRowDeleting="CustomersGridView_RowDeleting"
        DataKeyNames="CustomerID,AddressID">
        <Columns>
            <asp:BoundField DataField="FirstName" 
                HeaderText="FirstName" SortExpression="FirstName" />
            <asp:BoundField DataField="LastName" HeaderText="LastName" 
                SortExpression="LastName" />
            <asp:BoundField DataField="City" HeaderText="City" 
                SortExpression="City" />
            <asp:BoundField DataField="StateProvince" HeaderText="State" 
                SortExpression="StateProvince" />
        </Columns>
    </asp:GridView>
    <asp:SqlDataSource ID="CustomersSqlDataSource" runat="server"
        SelectCommand="SELECT SalesLT.CustomerAddress.CustomerID, 
            SalesLT.CustomerAddress.AddressID, 
            SalesLT.Customer.FirstName, 
            SalesLT.Customer.LastName, 
            SalesLT.Address.City, 
            SalesLT.Address.StateProvince 
            FROM SalesLT.Customer 
            INNER JOIN SalesLT.CustomerAddress 
            ON SalesLT.Customer.CustomerID = 
                SalesLT.CustomerAddress.CustomerID 
            INNER JOIN SalesLT.Address ON SalesLT.CustomerAddress.AddressID = 
                SalesLT.Address.AddressID"
        DeleteCommand="Delete from SalesLT.CustomerAddress where CustomerID = 
            @CustomerID and AddressID = @AddressID" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>">
        <DeleteParameters>
            <asp:Parameter Name="AddressID" />
            <asp:Parameter Name="CustomerID" />
        </DeleteParameters>
    </asp:SqlDataSource>
    </form>
</body>
</html>

Элемент GridView управления вызывает RowDeleting событие при нажатии кнопки Удалить (кнопка со свойством CommandName "Удалить"), но перед удалением GridView записи элементом управления. Это позволяет предоставить метод обработки событий, который выполняет настраиваемую подпрограмму, например отмену операции удаления, при каждом возникновении этого события.

При создании делегата GridViewDeleteEventHandler необходимо указать метод, обрабатывающий событие. Чтобы связать событие с обработчиком событий, нужно добавить в событие экземпляр делегата. Обработчик событий вызывается всякий раз, когда происходит событие, если делегат не удален. Дополнительные сведения о делегатах обработчика событий см. в разделе Обработка и вызов событий.

Методы расширения

GetMethodInfo(Delegate)

Получает объект, представляющий метод, представленный указанным делегатом.

Применяется к

Поделиться через

GridViewDeleteEventHandler Делегат

Определение

Параметры

Примеры

Комментарии

Методы расширения

Применяется к

См. также раздел

Дополнительные ресурсы