GridViewDeleteEventHandler Delegát

Reference

Definice

Obor názvů:: System.Web.UI.WebControls

Sestavení:: System.Web.dll

Důležité

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Představuje metodu, která zpracovává RowDeleting událost GridView ovládacího prvku.

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)

Parametry

sender: Object

Zdroj události

e: GridViewDeleteEventArgs

Objekt GridViewDeleteEventArgs , který obsahuje data události.

Příklady

Následující příklad ukazuje, jak programově přidat GridViewDeleteEventHandler delegáta k RowDeleting události GridView ovládacího prvku.


<%@ 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>

Následující příklad ukazuje, jak deklarativně přidat GridViewDeleteEventHandler delegáta k RowDeleting události GridView ovládacího prvku.


<%@ 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>

Poznámky

Ovládací GridView prvek vyvolá RowDeleting událost, když kliknete na tlačítko Odstranit (tlačítko s CommandName jeho vlastností nastavenou na "Delete"), ale předtím, než GridView ovládací prvek odstraní záznam. To vám umožní poskytnout metodu zpracování událostí, která provádí vlastní rutinu, jako je například zrušení operace odstranění, kdykoli dojde k této události.

Při vytváření delegáta GridViewDeleteEventHandler identifikujete metodu, která bude zpracovávat událost. Pokud chcete událost přidružit k obslužné rutině události, přidejte do události instanci delegáta. Obslužná rutina události je volána při každém výskytu události, dokud neodeberete delegáta. Další informace o delegátech obslužné rutiny událostí najdete v tématu Zpracování a vyvolávání událostí.

Metody rozšíření

GetMethodInfo(Delegate)

Získá objekt, který představuje metodu reprezentovanou zadaným delegátem.

Platí pro