FormViewCommandEventHandler Délégué

  • Référence

Définition

Espace de noms:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Représente la méthode qui gère l'événement ItemCommand d'un contrôle FormView. Cette classe ne peut pas être héritée.

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)

Paramètres

sender
Object

Source de l'événement.

e
FormViewCommandEventArgs

FormViewCommandEventArgs qui contient les données d’événement.

Exemples

L’exemple suivant montre comment ajouter par programmation un FormViewCommandEventHandler délégué à l’événement ItemCommand d’un FormView contrôle.

<%@ 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>

L’exemple suivant montre comment ajouter de manière déclarative un FormViewCommandEventHandler délégué à l’événement ItemCommand d’un FormView contrôle.

<%@ 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>

Remarques

L’événement ItemCommand est déclenché lorsqu’un bouton du FormView contrôle est cliqué. Cela vous permet de fournir une méthode de gestion des événements qui effectue une routine personnalisée chaque fois que cet événement se produit.

Les boutons d’un FormView contrôle peuvent également appeler certaines des fonctionnalités intégrées du contrôle. Pour effectuer l’une de ces opérations, définissez la CommandName propriété d’un bouton sur l’une des valeurs du tableau suivant.

Valeur CommandName Description
« Annuler » Annule une opération de modification ou d’insertion et retourne le FormView contrôle au mode spécifié par la DefaultMode propriété . Déclenche les ModeChanged événements et ModeChanging .
"Delete" Supprime l’enregistrement actif. Déclenche les ItemDeleted événements et ItemDeleting .
« Modifier » Place le FormView contrôle en mode édition. Déclenche les ModeChanged événements et ModeChanging .
« Insérer » Insère l'enregistrement actif dans la source de données. Déclenche les ItemInserted événements et ItemInserting .
« Nouveau » Place le FormView contrôle en mode insertion. Déclenche les ModeChanged événements et ModeChanging .
« Page » Effectue une opération de pagination. Définissez la CommandArgument propriété du bouton sur « First », « Last », « Next », « Prev » ou un numéro de page pour spécifier le type d’opération de pagination à effectuer. Déclenche les PageIndexChanged événements et PageIndexChanging .
« Mise à jour » Met à jour l'enregistrement en cours dans la source de données. Déclenche les ItemUpdated événements et ItemUpdating .

Bien que l’événement ItemCommand soit déclenché lorsqu’un bouton répertorié dans le tableau précédent est cliqué, il est recommandé de gérer les événements répertoriés dans la table pour l’opération.

Lorsque vous créez un délégué FormViewCommandEventHandler, vous identifiez la méthode qui gérera l'événement. Pour associer l'événement au gestionnaire d'événements, ajoutez une instance du délégué à l'événement. Le gestionnaire d'événements est appelé chaque fois qu'un événement se produit, sauf si vous supprimez le délégué. Pour plus d’informations sur les délégués du gestionnaire d’événements, consultez Gestion et levée d’événements.

Méthodes d’extension

GetMethodInfo(Delegate)

Obtient un objet qui représente la méthode représentée par le délégué spécifié.

S’applique à

Voir aussi