FormView.DataItem Eigenschaft

Referenz

Definition

Namespace:: System.Web.UI.WebControls

Assembly:: System.Web.dll

Wichtig

Einige Informationen beziehen sich auf Vorabversionen, die vor dem Release ggf. grundlegend überarbeitet werden. Microsoft übernimmt hinsichtlich der hier bereitgestellten Informationen keine Gewährleistungen, seien sie ausdrücklich oder konkludent.

Ruft das an das FormView-Steuerelement gebundene Datenelement ab.

public:
 virtual property System::Object ^ DataItem { System::Object ^ get(); };

[System.ComponentModel.Browsable(false)]
public virtual object DataItem { get; }

[<System.ComponentModel.Browsable(false)>]
member this.DataItem : obj

Public Overridable ReadOnly Property DataItem As Object

Eigenschaftswert

Object

Ein Object, das das an das FormView-Steuerelement gebundene Datenelement darstellt.

Implementiert

DataItem

Attribute: BrowsableAttribute

Beispiele

Im folgenden Beispiel wird veranschaulicht, wie die DataItem Eigenschaft verwendet wird, um den Wert eines Felds im Datenelement zu bestimmen.

<%@ 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 child control.
      // The event handler must bind the appropriate value 
      // to the control.
      Label firstNameLabel = new Label();
      firstNameLabel.ID = "FirstNameLabel";
      firstNameLabel.DataBinding += new EventHandler(FirstNameLabel_DataBinding);
      
      LiteralControl lineBreak = new LiteralControl("<br/>");
      
      Label lastNameLabel = new Label();
      lastNameLabel.ID = "LastNameLabel";
      lastNameLabel.DataBinding += new EventHandler(LastNameLabel_DataBinding);

      // Add the controls to the Controls collection of the 
      // container control.
      container.Controls.Add(firstNameLabel);
      container.Controls.Add(lineBreak);
      container.Controls.Add(lastNameLabel);
    }
    
    // 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.PagerSettings.Mode = PagerButtons.NextPrevious;
    employeesFormView.HeaderText = "Employee Name";
    employeesFormView.RowStyle.BackColor = System.Drawing.Color.LightBlue;
    employeesFormView.HeaderStyle.BackColor = System.Drawing.Color.Silver;
    employeesFormView.PagerStyle.BackColor = System.Drawing.Color.Silver;

    // 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.
    DetailsViewPlaceHolder.Controls.Add(employeesFormView);

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" > 
  <head runat="server">
    <title>FormView Constructor Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>FormView Constructor Example</h3>
        
      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated FormView control.            -->       
      <asp:PlaceHolder id="DetailsViewPlaceHolder"
        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 child control.
      ' The event handler must bind the appropriate value 
      ' to the control.
      Dim firstNameLabel As New Label()
      firstNameLabel.ID = "FirstNameLabel"
      AddHandler firstNameLabel.DataBinding, AddressOf FirstNameLabel_DataBinding
      
      Dim lineBreak As LiteralControl = New LiteralControl("<br/>")
      
      Dim lastNameLabel As New Label()
      lastNameLabel.ID = "LastNameLabel"
      AddHandler lastNameLabel.DataBinding, AddressOf LastNameLabel_DataBinding

      ' Add the controls to the Controls collection of the 
      ' container control.
      container.Controls.Add(firstNameLabel)
      container.Controls.Add(lineBreak)
      container.Controls.Add(lastNameLabel)
    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.PagerSettings.Mode = PagerButtons.NextPrevious
    employeesFormView.HeaderText = "Employee Name"
    employeesFormView.RowStyle.BackColor = System.Drawing.Color.LightBlue
    employeesFormView.HeaderStyle.BackColor = System.Drawing.Color.Silver
    employeesFormView.PagerStyle.BackColor = System.Drawing.Color.Silver

    ' 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.
    DetailsViewPlaceHolder.Controls.Add(employeesFormView)

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" > 
  <head runat="server">
    <title>FormView Constructor Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>FormView Constructor Example</h3>
        
      <!-- Use a PlaceHolder control as the container for the -->
      <!-- dynamically generated FormView control.            -->       
      <asp:PlaceHolder id="DetailsViewPlaceHolder"
        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>

Hinweise

Verwenden Sie die DataItem Eigenschaft, um auf das an das FormView Steuerelement gebundene Datenelement zuzugreifen. Das Datenelement wird häufig verwendet, um direkt auf die Feldwerte des aktuellen Datensatzes zuzugreifen. Der Typ der Object von dieser Eigenschaft zurückgegebenen Eigenschaft variiert je nach Datenquelle. Wenn beispielsweise ein SqlDataSource Steuerelement an das FormView Steuerelement gebunden ist, wird ein DataRowView Objekt zurückgegeben.

Hinweis

Diese Eigenschaft ist nur verfügbar, nachdem die Datenbindung aufgetreten ist. Bevor die Datenbindung auftritt, gibt diese Eigenschaft zurück null. Diese Eigenschaft gilt auch nicht, wenn sich das FormView Steuerelement im Einfügemodus befindet und zurückgibt null.

Gilt für