DetailsViewUpdateEventHandler 委托

定义

表示处理 ItemUpdating 控件的 DetailsView 事件的方法。Represents the method that handles the ItemUpdating event of a DetailsView control.

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

参数

sender
Object

事件源。The source of the event.

e
DetailsViewUpdateEventArgs

包含事件数据的 DetailsViewUpdateEventArgsA DetailsViewUpdateEventArgs that contains the event data.

继承
DetailsViewUpdateEventHandler

示例

下面的代码示例演示如何以编程方式将DetailsViewUpdateEventHandler委托添加ItemUpdatingDetailsView控件的事件。The following code example demonstrates how to programmatically add a DetailsViewUpdateEventHandler delegate to the ItemUpdating event of a DetailsView control.


<%@ 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 DetailsView object.
    DetailsView customerDetailsView = new DetailsView();

    // Set the DetailsView object's properties.
    customerDetailsView.ID = "CustomerDetailsView";
    customerDetailsView.DataSourceID = "DetailsViewSource";
    customerDetailsView.AutoGenerateRows = true;
    customerDetailsView.AutoGenerateEditButton = true;
    customerDetailsView.AllowPaging = true;
    customerDetailsView.DataKeyNames = new String[1] { "CustomerID" };
    customerDetailsView.PagerSettings.Position = PagerPosition.Bottom;

    // Programmatically register the event-handling methods
    // for the DetailsView control.
    customerDetailsView.ItemUpdating 
      += new DetailsViewUpdateEventHandler(
      this.CustomerDetailsView_ItemUpdating);
    customerDetailsView.ModeChanging 
      += new DetailsViewModeEventHandler(
      this.CustomerDetailsView_ModeChanging);

    // Add the DetailsView object to the Controls collection
    // of the PlaceHolder control.
    DetailsViewPlaceHolder.Controls.Add(customerDetailsView);

  }
  
  void CustomerDetailsView_ItemUpdating(Object sender, 
    DetailsViewUpdateEventArgs e)
  {

    // Validate the field values entered by the user. This
    // example determines whether the user left any fields
    // empty. Use the NewValues property to access the new 
    // values entered by the user.
    ArrayList emptyFieldList = 
      ValidateFields((IOrderedDictionary)e.NewValues);

    if (emptyFieldList.Count > 0)
    {

      // The user left some fields empty. Display an error message.
      
      // Use the Keys property to retrieve the key field value.
      String keyValue = e.Keys["CustomerID"].ToString();

      MessageLabel.Text = 
        "You must enter a value for all fields of record " +
        keyValue + ".<br/>The following fields are missing:<br/><br/>";

      // Display the missing fields.
      foreach (String value in emptyFieldList)
      {
        // Use the OldValues property access the original value
        // of a field.
        MessageLabel.Text += value + " - Original Value = " + 
          e.OldValues[value].ToString() + "<br />";
      }

      // Cancel the update operation.
      e.Cancel = true;

    }
    else
    {
      // The field values passed validation. Clear the
      // error message label.
      MessageLabel.Text = "";
    }

  }

  ArrayList ValidateFields(IOrderedDictionary list)
  {
    
    // Create an ArrayList object to store the
    // names of any empty fields.
    ArrayList emptyFieldList = new ArrayList();

    // Iterate though the field values entered by
    // the user and check for an empty field. Empty
    // fields contain a null value.
    foreach (DictionaryEntry entry in list)
    {
      if (entry.Value == null)
      {
        // Add the field name to the ArrayList object.
        emptyFieldList.Add(entry.Key.ToString());
      }
    }

    return emptyFieldList;
  }

  void CustomerDetailsView_ModeChanging(Object sender, 
    DetailsViewModeEventArgs e)
  {
    if (e.CancelingEdit)
    {
      // The user canceled the update operation.
      // Clear the error message label.
      MessageLabel.Text = "";
    }
  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>DetailsViewUpdateEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>DetailsViewUpdateEventHandler Example</h3>
        
      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated DetailsView control.         -->       
      <asp:placeholder id="DetailsViewPlaceHolder"
        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="DetailsViewSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], 
          [City], [PostalCode], [Country] From [Customers]"
        updatecommand="Update [Customers] Set 
          [CompanyName]=@CompanyName, [Address]=@Address, 
          [City]=@City, [PostalCode]=@PostalCode, 
          [Country]=@Country 
          Where [CustomerID]=@CustomerID"
        connectionstring=
          "<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>
          
    </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 DetailsView object.
    Dim customerDetailsView As New DetailsView()

    ' Set the DetailsView object's properties.
    customerDetailsView.ID = "CustomerDetailsView"
    customerDetailsView.DataSourceID = "DetailsViewSource"
    customerDetailsView.AutoGenerateRows = True
    customerDetailsView.AutoGenerateEditButton = True
    customerDetailsView.AllowPaging = True
    customerDetailsView.PagerSettings.Position = PagerPosition.Bottom

    Dim keyArray() As String = {"CustomerID"}
    customerDetailsView.DataKeyNames = keyArray
    
    ' Programmatically register the event-handling methods
    ' for the DetailsView control.
    AddHandler customerDetailsView.ItemUpdating, _
      AddressOf CustomerDetailsView_ItemUpdating
    AddHandler customerDetailsView.ModeChanging, _
      AddressOf CustomerDetailsView_ModeChanging

    ' Add the DetailsView object to the Controls collection
    ' of the PlaceHolder control.
    DetailsViewPlaceHolder.Controls.Add(customerDetailsView)

  End Sub
  
  Sub CustomerDetailsView_ItemUpdating(ByVal sender As Object, _
    ByVal e As DetailsViewUpdateEventArgs)

    ' Validate the field values entered by the user. This
    ' example determines whether the user left any fields
    ' empty. Use the NewValues property to access the new 
    ' values entered by the user.
    Dim emptyFieldList As ArrayList = _
      ValidateFields(CType(e.NewValues, IOrderedDictionary))

    If emptyFieldList.Count > 0 Then

      ' The user left some fields empty. Display an error message.
      
      ' Use the Keys property to retrieve the key field value.
      Dim keyValue As String = e.Keys("CustomerID").ToString()

      MessageLabel.Text = _
        "You must enter a value for all fields of record " & _
        keyValue & ".<br/>The following fields are missing:<br/><br/>"

      ' Display the missing fields.
      Dim value As String
      For Each value In emptyFieldList
      
        ' Use the OldValues property access the original value
        ' of a field.
        MessageLabel.Text &= value & " - Original Value = " & _
          e.OldValues(value).ToString() & "<br />"
        
      Next

      ' Cancel the update operation.
      e.Cancel = True

    Else
    
      ' The field values passed validation. Clear the
      ' error message label.
      MessageLabel.Text = ""
      
    End If

  End Sub

    Function ValidateFields(ByVal list As IOrderedDictionary) _
      As ArrayList
    
        ' Create an ArrayList object to store the
        ' names of any empty fields.
        Dim emptyFieldList As New ArrayList()

        ' Iterate though the field values entered by
        ' the user and check for an empty field. Empty
        ' fields contain a null value.
        Dim entry As DictionaryEntry
    
        For Each entry In list
    
            If entry.Value Is Nothing Then
      
                ' Add the field name to the ArrayList object.
                emptyFieldList.Add(entry.Key.ToString())
        
            End If
        Next

        Return emptyFieldList
  
    End Function

  Sub CustomerDetailsView_ModeChanging(ByVal sender As Object, ByVal e As DetailsViewModeEventArgs)
  
    If e.CancelingEdit Then
      
      ' The user canceled the update operation.
      ' Clear the error message label.
      MessageLabel.Text = ""
    
    End If
    
  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>DetailsViewUpdateEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>DetailsViewUpdateEventHandler Example</h3>
        
      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated DetailsView control.         -->       
      <asp:placeholder id="DetailsViewPlaceHolder"
        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="DetailsViewSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], 
          [City], [PostalCode], [Country] From [Customers]"
        updatecommand="Update [Customers] Set 
          [CompanyName]=@CompanyName, [Address]=@Address, 
          [City]=@City, [PostalCode]=@PostalCode, 
          [Country]=@Country Where [CustomerID]=@CustomerID"
        connectionstring=
          "<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>
s    </form>
  </body>
</html>

下面的代码示例演示如何以声明方式将DetailsViewUpdateEventHandler委托添加ItemUpdatingDetailsView控件的事件。The following code example demonstrates how to declaratively add a DetailsViewUpdateEventHandler delegate to the ItemUpdating event of a DetailsView control.


<%@ 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 CustomerDetailsView_ItemUpdating(Object sender, 
    DetailsViewUpdateEventArgs e)
  {

    // Validate the field values entered by the user. This
    // example determines whether the user left any fields
    // empty. Use the NewValues property to access the new 
    // values entered by the user.
    ArrayList emptyFieldList = 
      ValidateFields((IOrderedDictionary)e.NewValues);

    if (emptyFieldList.Count > 0)
    {

      // The user left some fields empty. Display an error message.
      
      // Use the Keys property to retrieve the key field value.
      String keyValue = e.Keys["CustomerID"].ToString();

      MessageLabel.Text = 
        "You must enter a value for all fields of record " +
        keyValue + ".<br/>The following fields are missing:<br/><br/>";

      // Display the missing fields.
      foreach (String value in emptyFieldList)
      {
        // Use the OldValues property access the original value
        // of a field.
        MessageLabel.Text += value + " - Original Value = " + 
          e.OldValues[value].ToString() + "<br />";
      }

      // Cancel the update operation.
      e.Cancel = true;

    }
    else
    {
      // The field values passed validation. Clear the
      // error message label.
      MessageLabel.Text = "";
    }

  }

  ArrayList ValidateFields(IOrderedDictionary list)
  {
    
    // Create an ArrayList object to store the
    // names of any empty fields.
    ArrayList emptyFieldList = new ArrayList();

    // Iterate though the field values entered by
    // the user and check for an empty field. Empty
    // fields contain a null value.
    foreach (DictionaryEntry entry in list)
    {
      if (entry.Value == null)
      {
        // Add the field name to the ArrayList object.
        emptyFieldList.Add(entry.Key.ToString());
      }
    }

    return emptyFieldList;
  }

  void CustomerDetailsView_ModeChanging(Object sender, 
    DetailsViewModeEventArgs e)
  {
    if (e.CancelingEdit)
    {
      // The user canceled the update operation.
      // Clear the error message label.
      MessageLabel.Text = "";
    }
  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>DetailsViewUpdateEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>DetailsViewUpdateEventHandler Example</h3>
                       
      <asp:detailsview id="CustomerDetailsView"
        datasourceid="DetailsViewSource"
        autogeneraterows="true"
        autogenerateeditbutton="true"  
        allowpaging="true"
        datakeynames="CustomerID" 
        onitemupdating="CustomerDetailsView_ItemUpdating"
        onmodechanging="CustomerDetailsView_ModeChanging" 
        runat="server">
          
        <pagersettings position="Bottom"/> 
                  
      </asp:detailsview>
      
      <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="DetailsViewSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], 
          [City], [PostalCode], [Country] From [Customers]"
        updatecommand="Update [Customers] Set 
          [CompanyName]=@CompanyName, [Address]=@Address, 
          [City]=@City, [PostalCode]=@PostalCode, 
          [Country]=@Country 
          Where [CustomerID]=@CustomerID"
        connectionstring=
          "<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>
          
    </form>
  </body>
</html>


<%@ Page language="VB" autoeventwireup="false" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
  
  Sub CustomerDetailsView_ItemUpdating(ByVal sender As Object, ByVal e As DetailsViewUpdateEventArgs) Handles CustomerDetailsView.ItemUpdating

    ' Validate the field values entered by the user. This
    ' example determines whether the user left any fields
    ' empty. Use the NewValues property to access the new 
    ' values entered by the user.
        Dim emptyFieldList As ArrayList = ValidateFields(CType(e.NewValues, IOrderedDictionary))

    If emptyFieldList.Count > 0 Then

      ' The user left some fields empty. Display an error message.
      
      ' Use the Keys property to retrieve the key field value.
      Dim keyValue As String = e.Keys("CustomerID").ToString()

      MessageLabel.Text = "You must enter a value for all fields of record " & _
        keyValue & ".<br/>The following fields are missing:<br/><br/>"

      ' Display the missing fields.
      Dim value As String
      For Each value In emptyFieldList
      
        ' Use the OldValues property access the original value
        ' of a field.
        MessageLabel.Text &= value & " - Original Value = " & _
          e.OldValues(value).ToString() & "<br />"
        
      Next

      ' Cancel the update operation.
      e.Cancel = True

    Else
    
      ' The field values passed validation. Clear the
      ' error message label.
      MessageLabel.Text = ""
      
    End If

  End Sub

    Function ValidateFields(ByVal list As IOrderedDictionary) As ArrayList
    
        ' Create an ArrayList object to store the
        ' names of any empty fields.
        Dim emptyFieldList As New ArrayList()

        ' Iterate though the field values entered by
        ' the user and check for an empty field. Empty
        ' fields contain a null value.
        Dim entry As DictionaryEntry
    
        For Each entry In list
    
            If entry.Value Is Nothing Then
      
                ' Add the field name to the ArrayList object.
                emptyFieldList.Add(entry.Key.ToString())
        
            End If
        Next

        Return emptyFieldList
  
    End Function

  Sub CustomerDetailsView_ModeChanging(ByVal sender As Object, ByVal e As DetailsViewModeEventArgs) Handles CustomerDetailsView.ModeChanging
  
    If e.CancelingEdit Then
      
      ' The user canceled the update operation.
      ' Clear the error message label.
      MessageLabel.Text = ""
    
    End If
    
  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>DetailsViewUpdateEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>DetailsViewUpdateEventHandler Example</h3>
                       
      <asp:detailsview id="CustomerDetailsView"
        datasourceid="DetailsViewSource"
        autogeneraterows="true"
        autogenerateeditbutton="true"  
        allowpaging="true"
        datakeynames="CustomerID" 
        runat="server">
          
        <pagersettings position="Bottom"/> 
                  
      </asp:detailsview>
      
      <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="DetailsViewSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], 
          [City], [PostalCode], [Country] From [Customers]"
        updatecommand="Update [Customers] Set 
          [CompanyName]=@CompanyName, [Address]=@Address, 
          [City]=@City, [PostalCode]=@PostalCode, 
          [Country]=@Country 
          Where [CustomerID]=@CustomerID"
        connectionstring=
          "<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>
          
    </form>
  </body>
</html>

注解

当单击控件中ItemUpdating的 "更新" 按钮 (其CommandName属性设置为 "Update") 时, 但在DetailsView控件更新记录之前,控件引发事件。DetailsViewThe DetailsView control raises the ItemUpdating event when an Update button (a button with its CommandName property set to "Update") within the control is clicked, but before the DetailsView control updates the record. 这使您可以在每次发生此事件时, 提供一个执行自定义例程的事件处理程序, 如在数据源中更新记录之前对记录的值进行 HTML 编码。This allows you to provide an event handler that performs a custom routine, such as HTML-encoding the values of a record before updating it in the data source, whenever this event occurs.

创建 DetailsViewUpdateEventHandler 委托时,需要标识将处理该事件的方法。When you create a DetailsViewUpdateEventHandler delegate, you identify the method that will handle the event. 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。To associate the event with your event handler, add an instance of the delegate to the event. 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。The event handler is called whenever the event occurs, unless you remove the delegate. 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For more information about event-handler delegates, see Handling and Raising Events.

扩展方法

GetMethodInfo(Delegate)

获取指示指定委托表示的方法的对象。Gets an object that represents the method represented by the specified delegate.

适用于

另请参阅