FormView.DataItem プロパティ

.NET Framework クラス ライブラリ リファレンス

FormView.DataItem プロパティ

メモ : このプロパティは、.NET Framework version 2.0 で新しく追加されたものです。

FormView コントロールにバインドされたデータ項目を取得します。

名前空間: System.Web.UI.WebControls
アセンブリ: System.Web (system.web.dll 内)
構文

Visual Basic (宣言)

Public Overridable ReadOnly
 Property DataItem As Object

Visual Basic (使用法)

Dim instance As FormView
Dim value As Object

value = instance.DataItem

C#

public virtual Object DataItem { get; }

C++

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

J#

/** @property */
public Object get_DataItem ()

JScript

public function get DataItem
 () : Object

プロパティ値
FormView コントロールにバインドされたデータ項目を表す Object。

解説

DataItem プロパティを使用して、FormView コントロールにバインドされたデータ項目にアクセスします。データ項目は、現在のレコードのフィールド値に直接アクセスする場合によく使用されます。このプロパティから返される Object の型は、データ ソースによって異なります。たとえば、SqlDataSource コントロールが FormView コントロールにバインドされている場合は、DataRowView オブジェクトが返されます。

メモ
このプロパティは、データ バインディングが発生した後にしか使用できません。まだデータ バインディングが発生していない場合、このプロパティは null 参照 (Visual Basic では Nothing) を返します。また、このプロパティは、FormView コントロールが挿入モードの場合にも適用できず、null 参照 (Visual Basic では Nothing) を返します。

使用例

DataItem プロパティを使用して、データ項目のフィールドの値を確認する方法を次の例に示します。

Visual Basic

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

<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> 
  <body>
    <form 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>

C#

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

<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> 
  <body>
    <form 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>

プラットフォーム

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework
サポート対象 : 2.0

参照

関連項目
FormView クラス
FormView メンバ
System.Web.UI.WebControls 名前空間
Object
Eval
DataItemCount
DataItemIndex