通过

FormViewCommandEventHandler 委托

  • 参考

定义

命名空间:
System.Web.UI.WebControls
程序集:
System.Web.dll

表示处理 ItemCommand 控件的 FormView 事件的方法。 此类不能被继承。

public delegate void FormViewCommandEventHandler(System::Object ^ sender, FormViewCommandEventArgs ^ e);
public delegate void FormViewCommandEventHandler(object sender, FormViewCommandEventArgs e);
type FormViewCommandEventHandler = delegate of obj * FormViewCommandEventArgs -> unit
Public Delegate Sub FormViewCommandEventHandler(sender As Object, e As FormViewCommandEventArgs)

参数

sender
Object

事件源。

e
FormViewCommandEventArgs

包含事件数据的 FormViewCommandEventArgs。

示例

下面的示例演示如何以编程方式向 控件的 FormView 事件添加FormViewCommandEventHandler委托ItemCommand。

<%@ page language="C#" %>
<%@ import namespace="System.Data"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
  
  // To dynamically create a template for a FormView control,
  // you must create a custom template class to represent 
  // the template. This template class represents the item
  // template for a FormView control.
  private sealed class EmployeeTemplate : ITemplate
  {
    
    // When implementing the ITemplate interface, you must
    // implement the InstantiateIn method. The FormView
    // control calls this method to create the template's 
    // content. 
    void ITemplate.InstantiateIn(Control container)
    {
      // Create the child controls contained in the template.
      // For this example, the item template displays the
      // FirstName and LastName fields from the data source.
      // To support data binding, create event handlers 
      // for the DataBinding event of each child control.
      // The event handlers must bind the appropriate value 
      // to each control.
      Label firstNameLabel = new Label();
      firstNameLabel.ID = "FirstNameLabel";
      firstNameLabel.DataBinding += new EventHandler(FirstNameLabel_DataBinding);
      
      LiteralControl nameLineBreak = new LiteralControl("<br/>");
      LiteralControl buttonLineBreak = new LiteralControl("<br/>");

      Label lastNameLabel = new Label();
      lastNameLabel.ID = "LastNameLabel";
      lastNameLabel.DataBinding += new EventHandler(LastNameLabel_DataBinding);

      // Create a custom button control to display in the item
      // template. When a button within a FormView control is 
      // clicked, the ItemCommand event is raised. The ItemCommand
      // event is used to handle the clicking of this button.
      Button displayButton = new Button();
      displayButton.ID = "AddButton";
      displayButton.CommandName = "Display";
      displayButton.Text = "Display Employee";

      // Add the controls to the Controls collection of the 
      // container control.
      container.Controls.Add(firstNameLabel);
      container.Controls.Add(nameLineBreak);
      container.Controls.Add(lastNameLabel);
      container.Controls.Add(buttonLineBreak);
      container.Controls.Add(displayButton);

    }
    
    // This event handler binds the value of the FirstName field
    // to the FirstNameLabel Label control displayed in the template.
    private void FirstNameLabel_DataBinding(Object sender, EventArgs e)
    {
      // Use the sender parameter to retrieve the Label control
      // being bound to data.
      Label firstNameLabelControl = (Label)sender;

      // Retrieve the value to bind to the Label control. First,
      // use the NamingContainer property to retrieve the parent 
      // control of the Label control. In this example, the parent 
      // control is the FormView control.
      FormView formViewContainer = (FormView)firstNameLabelControl.NamingContainer;
      
      // Get the data item bound to the FormView control.
      DataRowView rowView = (DataRowView)formViewContainer.DataItem;

      // Use the data item to retrieve the value of the FirstName field.
      // Set the Text property of the Label control to this value.        
      firstNameLabelControl.Text = rowView["FirstName"].ToString();
    }

    // This event handler binds the value of the LastName field
    // to the LastNameLabel Label control displayed in the template.
    private void LastNameLabel_DataBinding(Object sender, EventArgs e)
    {
      // Use the sender parameter to retrieve the Label control
      // being bound to data.
      Label lastNameLabelControl = (Label)sender;

      // Retrieve the value to bind to the Label control. First,
      // use the NamingContainer property to retrieve the parent 
      // control of the Label control. In this example, the parent 
      // control is the FormView control.
      FormView formViewContainer = (FormView)lastNameLabelControl.NamingContainer;

      // Get the data item bound to the FormView control.
      DataRowView rowView = (DataRowView)formViewContainer.DataItem;

      // Use the data item to retrieve the value of the LastName field.
      // Set the Text property of the Label control to this value.         
      lastNameLabelControl.Text = rowView["LastName"].ToString();
    }
    
  }

  void Page_Load(Object sender, EventArgs e)
  {
    
    // Create a new FormView object.
    FormView employeesFormView = new FormView();
    
    // Set the FormView object's properties.
    employeesFormView.ID = "EmployeesFormView";
    employeesFormView.DataSourceID = "EmployeeSource";
    employeesFormView.AllowPaging = true;
    employeesFormView.HeaderText = "Employee Name";
    
    // Programmatically register the event handlers for the 
    // FormView control.
    employeesFormView.ItemCommand += new FormViewCommandEventHandler(EmployeesFormView_ItemCommand);
    employeesFormView.PageIndexChanged += new EventHandler(EmployeesFormView_PageIndexChanged);

    // Create the dynamic template using the custom template class.
    employeesFormView.ItemTemplate = new EmployeeTemplate();

    // Add the FormView object to the Controls collection
    // of the PlaceHolder control.
    FormViewPlaceHolder.Controls.Add(employeesFormView);

  }

  void EmployeesFormView_ItemCommand(Object sender, FormViewCommandEventArgs e)
  {

    // The ItemCommand event is raised when any button within
    // the FormView control is clicked. Use the CommandName property 
    // to determine which button was clicked. 
    if (e.CommandName == "Display")
    {
      
      // Use the sender parameter to get the FormView control
      // that contains the button clicked.
      FormView employeesFormView = (FormView)sender;

      // Use the Row property to retrieve the data row.
      FormViewRow row = employeesFormView.Row;

      // Retrieve the FirstNameLabel and LastNameLabel Label controls 
      // from the data row.
      Label firstNameLabel = (Label)row.FindControl("FirstNameLabel");
      Label lastNameLabel = (Label)row.FindControl("LastNameLabel");

      if (firstNameLabel != null && lastNameLabel != null)
      {
        // Display the employee's name.
        MessageLabel.Text = firstNameLabel.Text + " " + 
          lastNameLabel.Text;
      }
      
    }
    
  }

  void EmployeesFormView_PageIndexChanged(Object sender, EventArgs e)
  {
    
    // Clear the message label when the user navigates to 
    // a different record.
    MessageLabel.Text = "";

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" > 
  <head runat="server">
    <title>FormViewCommandEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>FormViewCommandEventHandler Example</h3>
        
      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated FormView control.            -->       
      <asp:placeholder id="FormViewPlaceHolder"
        runat="server"/>
            
      <br/><br/>
      
      <asp:label id="MessageLabel"
        forecolor="Red"
        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="EmployeeSource"
        selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>
          
    </form>
  </body>
</html>

<%@ page language="VB" %>
<%@ import namespace="System.Data"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
  
  ' To dynamically create a template for a FormView control,
  ' you must create a custom template class to represent 
  ' the template. This template class represents the item
  ' template for a FormView control.
  Private NotInheritable Class EmployeeTemplate
    Implements ITemplate
    
    ' When implementing the ITemplate interface, you must
    ' implement the InstantiateIn method. The FormView
    ' control calls this method to create the template's 
    ' content. 
    Sub InstantiateIn(ByVal container As Control) Implements ITemplate.InstantiateIn
    
      ' Create the child controls contained in the template.
      ' For this example, the item template displays the
      ' FirstName and LastName fields from the data source.
      ' To support data-binding, create event handlers 
      ' for the DataBinding event of each child control.
      ' The event handlers must bind the appropriate value 
      ' to each control.
      Dim firstNameLabel As New Label()
      firstNameLabel.ID = "FirstNameLabel"
      AddHandler firstNameLabel.DataBinding, AddressOf FirstNameLabel_DataBinding
      
      Dim nameLineBreak As New LiteralControl("<br/>")
      Dim buttonLineBreak As New LiteralControl("<br/>")

      Dim lastNameLabel As New Label()
      lastNameLabel.ID = "LastNameLabel"
      AddHandler lastNameLabel.DataBinding, AddressOf LastNameLabel_DataBinding

      ' Create a custom button control to display in the item
      ' template. When a button within a FormView control is 
      ' clicked, the ItemCommand event is raised. The ItemCommand
      ' event is used to handle the clicking of this button.
      Dim displayButton As New Button()
      displayButton.ID = "AddButton"
      displayButton.CommandName = "Display"
      displayButton.Text = "Display Employee"

      ' Add the controls to the Controls collection of the 
      ' container control.
      container.Controls.Add(firstNameLabel)
      container.Controls.Add(nameLineBreak)
      container.Controls.Add(lastNameLabel)
      container.Controls.Add(buttonLineBreak)
      container.Controls.Add(displayButton)

    End Sub
    
    ' This event handler binds the value of the FirstName field
    ' to the FirstNameLabel Label control displayed in the template.
    Private Sub FirstNameLabel_DataBinding(ByVal sender As Object, ByVal e As EventArgs)

      ' Use the sender parameter to retrieve the Label control
      ' being bound to data.
      Dim firstNameLabelControl As Label = CType(sender, Label)

      ' Retrieve the value to bind to the Label control. First,
      ' use the NamingContainer property to retrieve the parent 
      ' control of the Label control. In this example, the parent 
      ' control is the FormView control.
      Dim formViewContainer As FormView = CType(firstNameLabelControl.NamingContainer, FormView)
      
      ' Get the data item bound to the FormView control.
      Dim rowView As DataRowView = CType(formViewContainer.DataItem, DataRowView)

      ' Use the data item to retrieve the value of the FirstName field.
      ' Set the Text property of the Label control to this value.        
      firstNameLabelControl.Text = rowView("FirstName").ToString()
  
    End Sub

    ' This event handler binds the value of the LastName field
    ' to the LastNameLabel Label control displayed in the template.
    Private Sub LastNameLabel_DataBinding(ByVal sender As Object, ByVal e As EventArgs)

      ' Use the sender parameter to retrieve the Label control
      ' being bound to data.
      Dim lastNameLabelControl As Label = CType(sender, Label)

      ' Retrieve the value to bind to the Label control. First,
      ' use the NamingContainer property to retrieve the parent 
      ' control of the Label control. In this example, the parent 
      ' control is the FormView control.
      Dim formViewContainer As FormView = CType(lastNameLabelControl.NamingContainer, FormView)

      ' Get the data item bound to the FormView control.
      Dim rowView As DataRowView = CType(formViewContainer.DataItem, DataRowView)

      ' Use the data item to retrieve the value of the LastName field.
      ' Set the Text property of the Label control to this value.         
      lastNameLabelControl.Text = rowView("LastName").ToString()
    
    End Sub

  End Class
  
  Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
      
    ' Create a new FormView object.
    Dim employeesFormView As New FormView()
    
    ' Set the FormView object's properties.
    employeesFormView.ID = "EmployeesFormView"
    employeesFormView.DataSourceID = "EmployeeSource"
    employeesFormView.AllowPaging = True
    employeesFormView.HeaderText = "Employee Name"
    
    ' Programmatically register the event handlers for the 
    ' FormView control.
    AddHandler employeesFormView.ItemCommand, AddressOf EmployeesFormView_ItemCommand
    AddHandler employeesFormView.PageIndexChanged, AddressOf EmployeesFormView_PageIndexChanged

    ' Create the dynamic template using the custom template class.
    employeesFormView.ItemTemplate = New EmployeeTemplate()

    ' Add the FormView object to the Controls collection
    ' of the PlaceHolder control.
    FormViewPlaceHolder.Controls.Add(employeesFormView)

  End Sub

  Sub EmployeesFormView_ItemCommand(ByVal sender As Object, ByVal e As FormViewCommandEventArgs)

    ' The ItemCommand event is raised when any button within
    ' the FormView control is clicked. Use the CommandName property 
    ' to determine which button was clicked. 
    If e.CommandName = "Display" Then
      
      ' Use the sender parameter to get the FormView control
      ' that contains the button clicked.
      Dim employeesFormView As FormView = CType(sender, FormView)

      ' Use the Row property to retrieve the data row.
      Dim row As FormViewRow = employeesFormView.Row

      ' Retrieve the FirstNameLabel and LastNameLabel Label controls 
      ' from the data row.
      Dim firstNameLabel As Label = CType(row.FindControl("FirstNameLabel"), Label)
      Dim lastNameLabel As Label = CType(row.FindControl("LastNameLabel"), Label)

      If firstNameLabel IsNot Nothing And lastNameLabel IsNot Nothing Then
      
        ' Display the employee's name.
        MessageLabel.Text = firstNameLabel.Text & " " & _
        lastNameLabel.Text()
        
      End If
      
    End If
    
  End Sub
  
  Sub EmployeesFormView_PageIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
    
    ' Clear the message label when the user navigates to 
    ' a different record.
    MessageLabel.Text = ""

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" > 
  <head runat="server">
    <title>FormViewCommandEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>FormViewCommandEventHandler Example</h3>
        
      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated FormView control.            -->       
      <asp:placeholder id="FormViewPlaceHolder"
        runat="server"/>
            
      <br/><br/>
      
      <asp:label id="MessageLabel"
        forecolor="Red"
        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="EmployeeSource"
        selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>
          
    </form>
  </body>
</html>

以下示例演示如何以声明方式向 控件的 FormView 事件添加FormViewCommandEventHandler委托ItemCommand。

<%@ page language="C#" %>
<%@ import namespace="System.Data"%>

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

  void EmployeesFormView_ItemCommand(Object sender, FormViewCommandEventArgs e)
  {

    // The ItemCommand event is raised when any button within
    // the FormView control is clicked. Use the CommandName property 
    // to determine which button was clicked. 
    if (e.CommandName == "Display")
    {

      // Use the Row property to retrieve the data row.
      FormViewRow row = EmployeesFormView.Row;

      // Retrieve the FirstNameLabel and LastNameLabel Label controls 
      // from data row.
      Label firstNameLabel = (Label)row.FindControl("FirstNameLabel");
      Label lastNameLabel = (Label)row.FindControl("LastNameLabel");

      if (firstNameLabel != null && lastNameLabel != null)
      {
        // Display the employee's name.
        MessageLabel.Text = firstNameLabel.Text + " " + 
          lastNameLabel.Text;
      }
      
    }
    
  }

  void EmployeesFormView_PageIndexChanged(Object sender, EventArgs e)
  {
    
    // Clear the message label when the user navigates to 
    // a different record.
    MessageLabel.Text = "";

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" > 
  <head runat="server">
    <title>FormViewCommandEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>FormViewCommandEventHandler Example</h3>
        
      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated FormView control.            -->       
      <asp:formview id="EmployeesFormView"
        datasourceid="EmployeeSource"
        allowpaging="True"
        headertext="Employee Name"
        onitemcommand="EmployeesFormView_ItemCommand"
        onpageindexchanged="EmployeesFormView_PageIndexChanged"
        runat="server">
      
        <itemtemplate>
        
          <asp:label id="FirstNameLabel"
            text='<%# Eval("FirstName") %>'
            runat="server"/>
          <br/>
          <asp:label id="LastNameLabel"
            text='<%# Eval("LastName") %>'
            runat="server"/>
          <br/>
          <asp:button
            id="DisplayButton"
            text="Display Employee"
            commandname="Display" 
            runat="server"/>
        
        </itemtemplate>
        
      </asp:formview>
            
      <br/><br/>
      
      <asp:label id="MessageLabel"
        forecolor="Red"
        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="EmployeeSource"
        selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>
          
    </form>
  </body>
</html>

<%@ page language="VB" %>
<%@ import namespace="System.Data"%>

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

  Sub EmployeesFormView_ItemCommand(ByVal sender As Object, ByVal e As FormViewCommandEventArgs) Handles EmployeesFormView.ItemCommand

    ' The ItemCommand event is raised when any button within
    ' the FormView control is clicked. Use the CommandName property 
    ' to determine which button was clicked. 
    If e.CommandName = "Display" Then

      ' Use the Row property to retrieve the data row.
      Dim row As FormViewRow = EmployeesFormView.Row

      ' Retrieve the FirstNameLabel and LastNameLabel Label controls 
      ' from data row.
      Dim firstNameLabel As Label = CType(row.FindControl("FirstNameLabel"), Label)
      Dim lastNameLabel As Label = CType(row.FindControl("LastNameLabel"), Label)

      If firstNameLabel IsNot Nothing And lastNameLabel IsNot Nothing Then

        ' Display the employee's name.
        MessageLabel.Text = firstNameLabel.Text & " " & _
          lastNameLabel.Text()
        
      End If
      
    End If
    
  End Sub

  Sub EmployeesFormView_PageIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles EmployeesFormView.PageIndexChanged
    
    ' Clear the message label when the user navigates to 
    ' a different record.
    MessageLabel.Text = ""

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" > 
  <head runat="server">
    <title>FormViewCommandEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>FormViewCommandEventHandler Example</h3>
        
      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated FormView control.            -->       
      <asp:formview id="EmployeesFormView"
        datasourceid="EmployeeSource"
        allowpaging="True"
        headertext="Employee Name"
        runat="server">
      
        <itemtemplate>
        
          <asp:label id="FirstNameLabel"
            text='<%# Eval("FirstName") %>'
            runat="server"/>
          <br/>
          <asp:label id="LastNameLabel"
            text='<%# Eval("LastName") %>'
            runat="server"/>
          <br/>
          <asp:button
            id="DisplayButton"
            text="Display Employee"
            commandname="Display" 
            runat="server"/>
        
        </itemtemplate>
        
      </asp:formview>
            
      <br/><br/>
      
      <asp:label id="MessageLabel"
        forecolor="Red"
        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="EmployeeSource"
        selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>
          
    </form>
  </body>
</html>

注解

单击 ItemCommand 控件中的 FormView 按钮时，将引发 事件。 这允许你提供一个事件处理方法，该方法在发生此事件时执行自定义例程。

控件中的 FormView 按钮还可以调用控件的某些内置功能。 若要执行这些操作之一，请将按钮的 属性设置为 CommandName 下表中的值之一。

CommandName 值 说明
“取消” 取消编辑或插入操作，并将 FormView 控件返回到 属性指定的 DefaultMode 模式。 引发 ModeChanged 和 ModeChanging 事件。
“Delete” 删除当前记录。 引发 ItemDeleted 和 ItemDeleting 事件。
“编辑” 将 FormView 控件置于编辑模式。 引发 ModeChanged 和 ModeChanging 事件。
“插入” 将当前记录插入到数据源中。 引发 ItemInserted 和 ItemInserting 事件。
“新建” 将 FormView 控件置于插入模式。 引发 ModeChanged 和 ModeChanging 事件。
“Page” 执行分页操作。 CommandArgument将按钮的 属性设置为“First”、“Last”、“Next”、“Prev”或页码，以指定要执行的分页操作的类型。 引发 PageIndexChanged 和 PageIndexChanging 事件。
“Update” 更新数据源中的当前记录。 引发 ItemUpdated 和 ItemUpdating 事件。

尽管在 ItemCommand 单击上一表中列出的按钮时会引发 事件，但建议你为操作处理表中列出的事件。

创建 FormViewCommandEventHandler 委托时，需要标识将处理该事件的方法。 若要将事件与事件处理程序关联，请将该委托的一个实例添加到事件中。 除非移除了该委托，否则每当发生该事件时就会调用事件处理程序。 有关事件处理程序委托的详细信息，请参阅 处理和引发事件。

扩展方法

GetMethodInfo(Delegate)

获取指示指定委托表示的方法的对象。

适用于

另请参阅