ObjectDataSource.UpdateMethod プロパティとは何？わかりやすく解説 Weblio辞書

.NET Framework クラスライブラリリファレンス

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ObjectDataSource.UpdateMethod 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。

ObjectDataSource コントロールがデータを更新するために呼び出すメソッドまたは関数の名前を取得または設定します。

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 Property UpdateMethod As
 String

Visual Basic (使用法)

Dim instance As ObjectDataSource
Dim value As String

value = instance.UpdateMethod

instance.UpdateMethod = value

public string UpdateMethod { get;
 set; }

C++

public:
property String^ UpdateMethod {
    String^ get ();
    void set (String^ value);
}

/** @property */
public String get_UpdateMethod ()

/** @property */
public void set_UpdateMethod (String value)

JScript

public function get UpdateMethod
 () : String

public function set UpdateMethod
 (value : String)

プロパティ値
ObjectDataSource がデータを更新するために使用するメソッドまたは関数の名前を表す文字列。既定値は空の文字列です。

解説

ObjectDataSource コントロールは、UpdateMethod プロパティで識別されるメソッドが、バッチではなく、一度に 1 つずつ更新を実行することを前提としています。

UpdateMethod プロパティは、ObjectDataSource コントロールに関連付けられた ObjectDataSourceView オブジェクトの UpdateMethod プロパティに処理を代行させます。

オブジェクトの有効期間

UpdateMethod プロパティで識別されるメソッドには、インスタンスメソッドまたは static (Visual Basic の場合は Shared) メソッドを指定できます。インスタンスメソッドの場合、UpdateMethod プロパティで指定されたメソッドが呼び出されるたびにビジネスオブジェクトが作成され、破棄されます。ObjectCreated イベントと ObjectCreating イベントを処理することで、UpdateMethod プロパティで指定されたメソッドが呼び出される前に、ビジネスオブジェクトを使用できます。UpdateMethod プロパティで指定されたメソッドが呼び出された後に発生する ObjectDisposing イベントを処理することもできます。ビジネスオブジェクトが IDisposable インターフェイスを実装している場合は、オブジェクトが破棄される前に Dispose メソッドが呼び出されます。メソッドが static (Visual Basic では Shared) の場合、ビジネスオブジェクトは作成されず、ObjectCreated、ObjectCreating、および ObjectDisposing の各イベントを処理できません。

パラメータのマージ

パラメータは、次の 3 つのソースから DeleteParameters コレクションに追加されます。

まず、データバインドコントロールから生成されたパラメータが UpdateParameters コレクションに追加されます。たとえば、ObjectDataSource コントロールが Name 列と Number 列を持つ GridView コントロールにバインドされている場合、Name および Number に対応するパラメータがコレクションに追加されます。パラメータの正確な名前は、OldValuesParameterFormatString プロパティによって決まります。これらのパラメータのデータ型は string です。次に、UpdateParameters 要素にリストされたパラメータが追加されます。UpdateParameters 要素のパラメータが UpdateParameters コレクション内の既存のパラメータと同じ名前で存在する場合、UpdateParameters 要素で指定されたパラメータと一致するように既存のパラメータが変更されます。通常、これはパラメータのデータの型を変更するために使用されます。最後に、Updating イベントでプログラムによってパラメータを追加および削除できます。このイベントは、Update メソッドが実行される前に発生します。メソッドは、パラメータがマージされた後に解決されます。メソッドの解決については、次のセクションで説明します。

メソッドの解決

Update メソッドが呼び出されると、データバインドコントロールのデータフィールド、UpdateParameters 要素で宣言によって作成されたパラメータ、および Updating イベントハンドラで追加されたパラメータがすべてマージされます (詳細については、前のセクションを参照してください)。次に、ObjectDataSource コントロールは、呼び出すメソッドの検索を試みます。まず、UpdateMethod プロパティで指定された名前を持つ 1 つ以上のメソッドが検索されます。一致するメソッドが見つからない場合、InvalidOperationException 例外がスローされます。一致するメソッドが見つかった場合は、一致するパラメータ名が検索されます。たとえば、TypeName プロパティで指定された型に UpdateARecord という名前のメソッドが 2 つあるとします。一方の UpdateARecord には、ID というパラメータが 1 つあり、もう一方の UpdateARecord には、Name と Number という 2 つのパラメータがあります。UpdateParameters コレクションに ID という名前のパラメータが 1 つしかない場合、ID パラメータだけを持つ UpdateARecord メソッドが呼び出されます。メソッドの解決時に、パラメータの型はチェックされません。パラメータの順序は重要ではありません。

DataObjectTypeName プロパティが設定されている場合には、メソッドは別の方法で解決されます。ObjectDataSource は、DataObjectTypeName プロパティで指定された型のパラメータを 1 つ受け取る UpdateMethod プロパティで指定された名前のメソッドを検索します。この場合、パラメータの名前は重要ではありません。

使用例

このセクションには、2 つのコード例が含まれています。1 つ目のコード例では、DropDownList コントロール、TextBox コントロール、および複数の ObjectDataSource オブジェクトを使用してデータを更新する方法を示します。2 つ目のコード例では、1 つ目のコード例で使用されている EmployeeLogic クラスを示します。

DropDownList コントロール、TextBox コントロール、および複数の ObjectDataSource コントロールを使用してデータを更新する方法を次のコード例に示します。TextBox コントロールがアドレス情報の入力と更新に使用されるのに対し、DropDownList は、Northwind の従業員の名前を表示します。UpdateParameters コレクションには、DropDownList で選択された値にバインドされた ControlParameter オブジェクトが格納されているため、Update 操作を発生させるボタンは、従業員を選択するまで有効になりません。

Visual Basic

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB"
 Assembly="Samples.AspNet.VB"
 %>
<%@ Page language="vb" %>
<%@ Import namespace="Samples.AspNet.VB"
 %>

<Script runat="server">

' Add parameters and initialize the user interface
' only if an employee is selected.
Private Sub Page_Load(sender As
 Object, e As EventArgs)

  ' Be sure the text boxes are initialized with
  ' data from the currently selected employee.
  Dim selectedEmployee As NorthwindEmployee
  selectedEmployee = EmployeeLogic.GetEmployee(DropDownList1.SelectedValue)

  If Not selectedEmployee Is
 Nothing Then
    AddressBox.Text    = selectedEmployee.Address
    CityBox.Text       = selectedEmployee.City
    PostalCodeBox.Text = selectedEmployee.PostalCode

    Button1.Enabled = True
  Else
    Button1.Enabled = False
  End If
End Sub ' Page_Load

' Press the button to update.
Private Sub Btn_UpdateEmployee (sender As
 Object, e As CommandEventArgs )
  ObjectDataSource2.Update()
End Sub ' Btn_UpdateEmployee

</Script>
<html>
  <head>
    <title>ObjectDataSource - VB Example</title>
  </head>
  <body>
    <form id="Form1" method="post"
 runat="server">

        <!-- The DropDownList is bound to
 the first ObjectDataSource. -->
        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          typename="Samples.AspNet.VB.EmployeeLogic"
 />

        <p><asp:dropdownlist
          id="DropDownList1"
          runat="server"
          datasourceid="ObjectDataSource1"
          datatextfield="FullName"
          datavaluefield="EmpID"
          autopostback="True" /></p>

        <!-- The second ObjectDataSource performs the Update. This
             preserves the state of the DropDownList, which otherwise
             would rebind when the DataSourceChanged event
 is
             raised as a result of an Update
 operation. -->

        <!-- Security Note: The ObjectDataSource uses a FormParameter,
             Security Note: which does not perform validation
 of input from the client.
             Security Note: To validate the value of
 the FormParameter,
             Security Note: handle the Updating event. -->

        <asp:objectdatasource
          id="ObjectDataSource2"
          runat="server"
          updatemethod="UpdateEmployeeWrapper"
          typename="Samples.AspNet.VB.EmployeeLogic">
          <updateparameters>
            <asp:controlparameter name="anID" controlid="DropDownList1"
 propertyname="SelectedValue" />
            <asp:formparameter name="anAddress"
 formfield="AddressBox" />
            <asp:formparameter name="aCity" formfield="CityBox"
 />
            <asp:formparameter name="aPostalCode"
 formfield="PostalCodeBox" />
          </updateparameters>
        </asp:objectdatasource>

        <p><asp:textbox
          id="AddressBox"
          runat="server" /></p>

        <p><asp:textbox
          id="CityBox"
          runat="server" /></p>

        <p><asp:textbox
          id="PostalCodeBox"
          runat="server" /></p>

        <asp:button
          id="Button1"
          runat="server"
          text="Update Employee"
          oncommand="Btn_UpdateEmployee" />

    </form>
  </body>
</html>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS"
 Assembly="Samples.AspNet.CS" %>
<%@ Page language="c#" %>
<%@ Import namespace="Samples.AspNet.CS" %>
<Script runat="server">

// Add parameters and initialize the user interface
// only if an employee is selected.
private void Page_Load(object sender, EventArgs
 e)
{
  // Be sure the text boxes are initialized with
  // data from the currently selected employee.
  NorthwindEmployee selectedEmployee = EmployeeLogic.GetEmployee(DropDownList1.SelectedValue);
  if (selectedEmployee != null) {
    AddressBox.Text    = selectedEmployee.Address;
    CityBox.Text       = selectedEmployee.City;
    PostalCodeBox.Text = selectedEmployee.PostalCode;

    Button1.Enabled = true;
  }
  else {
    Button1.Enabled = false;
  }
}

// Press the button to update.
private void Btn_UpdateEmployee (object sender,
 CommandEventArgs e) {
  ObjectDataSource2.Update();
}
</Script>
<html>
  <head>
    <title>ObjectDataSource - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <!-- The DropDownList is bound to the first ObjectDataSource. -->
        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          typename="Samples.AspNet.CS.EmployeeLogic" />

        <p><asp:dropdownlist
          id="DropDownList1"
          runat="server"
          datasourceid="ObjectDataSource1"
          datatextfield="FullName"
          datavaluefield="EmpID"
          autopostback="True" /></p>

        <!-- The second ObjectDataSource performs the Update. This
             preserves the state of the DropDownList, which otherwise
             would rebind when the DataSourceChanged event is
             raised as a result of an Update operation. -->

        <!-- Security Note: The ObjectDataSource uses a FormParameter,
             Security Note: which does not perform validation of input from the client.
             Security Note: To validate the value of the FormParameter,
             Security Note: handle the Updating event. -->

        <asp:objectdatasource
          id="ObjectDataSource2"
          runat="server"
          updatemethod="UpdateEmployeeWrapper"
          typename="Samples.AspNet.CS.EmployeeLogic">
          <updateparameters>
            <asp:controlparameter name="anID" controlid="DropDownList1"
 propertyname="SelectedValue" />
            <asp:formparameter name="anAddress" formfield="AddressBox"
 />
            <asp:formparameter name="aCity" formfield="CityBox"
 />
            <asp:formparameter name="aPostalCode" formfield="PostalCodeBox"
 />
          </updateparameters>
        </asp:objectdatasource>

        <p><asp:textbox
          id="AddressBox"
          runat="server" /></p>

        <p><asp:textbox
          id="CityBox"
          runat="server" /></p>

        <p><asp:textbox
          id="PostalCodeBox"
          runat="server" /></p>

        <asp:button
          id="Button1"
          runat="server"
          text="Update Employee"
          oncommand="Btn_UpdateEmployee" />

    </form>
  </body>
</html>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL"
 Assembly="Samples.AspNet.JSL" %>
<%@ Page language="VJ#" %>
<%@ Import namespace="Samples.AspNet.JSL" %>
<Script runat="server">

// Add parameters and initialize the user interface
// only if an employee is selected.
    private void Page_Load(Object sender, EventArgs
 e) throws NorthwindDataException
    {
        // Be sure the text boxes are initialized with
        // data from the currently selected employee.
        NorthwindEmployee selectedEmployee =
            EmployeeLogic.GetEmployee(DropDownList1.get_SelectedValue());
        if (selectedEmployee != null) {
            AddressBox.set_Text(selectedEmployee.get_Address());
            CityBox.set_Text(selectedEmployee.get_City());
            PostalCodeBox.set_Text(selectedEmployee.get_PostalCode());
            Button1.set_Enabled(true);
        }
        else {
            Button1.set_Enabled(false);
        }
    } //Page_Load

    // Press the button to update.
    private void Btn_UpdateEmployee(Object
 sender, CommandEventArgs e)
    {
        ObjectDataSource2.Update();
    } //Btn_UpdateEmployee
</Script>
<html>
  <head>
    <title>ObjectDataSource - VJ# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <!-- The DropDownList is bound to the first ObjectDataSource. -->
        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          typename="Samples.AspNet.JSL.EmployeeLogic" />

        <p><asp:dropdownlist
          id="DropDownList1"
          runat="server"
          datasourceid="ObjectDataSource1"
          datatextfield="FullName"
          datavaluefield="EmpID"
          autopostback="True" /></p>

        <!-- The second ObjectDataSource performs the Update. This
             preserves the state of the DropDownList, which otherwise
             would rebind when the DataSourceChanged event is
             raised as a result of an Update operation. -->

        <asp:objectdatasource
          id="ObjectDataSource2"
          runat="server"
          updatemethod="UpdateEmployeeWrapper"
          typename="Samples.AspNet.JSL.EmployeeLogic">
          <updateparameters>
            <asp:controlparameter name="anID" controlid="DropDownList1"
 propertyname="SelectedValue" />
            <asp:formparameter name="anAddress" formfield="AddressBox"
 />
            <asp:formparameter name="aCity" formfield="CityBox"
 />
            <asp:formparameter name="aPostalCode" formfield="PostalCodeBox"
 />
          </updateparameters>
        </asp:objectdatasource>

        <p><asp:textbox
          id="AddressBox"
          runat="server" /></p>

        <p><asp:textbox
          id="CityBox"
          runat="server" /></p>

        <p><asp:textbox
          id="PostalCodeBox"
          runat="server" /></p>

        <asp:button
          id="Button1"
          runat="server"
          text="Update Employee"
          oncommand="Btn_UpdateEmployee" />

    </form>
  </body>
</html>

前のコード例で使用されている EmployeeLogic クラスを次のコード例に示します。

Visual Basic

Imports System
Imports System.Collections
Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.UI
Imports System.Web.UI.WebControls

Namespace Samples.AspNet.VB
'
' EmployeeLogic is a stateless business object that encapsulates
' the operations one can perform on a NorthwindEmployee object.
'
Public Class EmployeeLogic

   ' Returns a collection of NorthwindEmployee objects.
   Public Shared Function
 GetAllEmployees() As ICollection
      Dim al As New ArrayList()

      ' Use the SqlDataSource class to wrap the
      ' ADO.NET code required to query the database.
      Dim cts As ConnectionStringSettings =
 ConfigurationManager.ConnectionStrings("NorthwindConnection")
      Dim sds As New SqlDataSource(cts.ConnectionString,
 _
                                  "SELECT EmployeeID FROM Employees")
      Try
         Dim IDs As IEnumerable = sds.Select(DataSourceSelectArguments.Empty)

         ' Iterate through the Enumeration and create a
         ' NorthwindEmployee object for each ID.
         Dim enumerator As IEnumerator = IDs.GetEnumerator()
         While enumerator.MoveNext()
            ' The IEnumerable contains DataRowView objects.
            Dim row As DataRowView = CType(enumerator.Current
,DataRowView)
            Dim id As String
 = row("EmployeeID").ToString()
            Dim nwe As New
 NorthwindEmployee(id)
            ' Add the NorthwindEmployee object to the collection.
            al.Add(nwe)
         End While
      Finally
         ' If anything strange happens, clean up.
         sds.Dispose()
      End Try

      Return al
   End Function 'GetAllEmployees


   Public Shared Function
 GetEmployee(anID As Object) As
 NorthwindEmployee
      Dim al As ArrayList = CType(GetAllEmployees(),
 ArrayList)
      Dim enumerator As IEnumerator = al.GetEnumerator()
      While enumerator.MoveNext()
         ' The IEnumerable contains initialized NorthwindEmployee objects.
         Dim ne As NorthwindEmployee = CType(enumerator.Current
,NorthwindEmployee)
         If ne.EmpID.Equals(anID.ToString()) Then
            Return ne
         End If
      End While
      Return Nothing
   End Function 'GetEmployee

   Public Shared Sub UpdateEmployee(ne
 As NorthwindEmployee)
      Dim retval As Boolean
 = ne.Update()
      If Not retval Then
         Throw New NorthwindDataException("Employee
 update failed.")
      End If
   End Sub 'UpdateEmployee

   ' This method is added as a conveniece wrapper on the original
   ' implementation.
   Public Shared Sub UpdateEmployeeWrapper(anID
 As String, _
                                           anAddress As String,
 _
                                           aCity As String,
 _
                                           aPostalCode As String)
      Dim ne As New NorthwindEmployee(anID)
      ne.Address = anAddress
      ne.City = aCity
      ne.PostalCode = aPostalCode
      UpdateEmployee(ne)
   End Sub 'UpdateEmployeeWrapper
   ' And so on...

End Class 'EmployeeLogic

Public Class NorthwindEmployee

   Public Sub New(anID As
 Object)
      Me.ID = anID
      Dim cts As ConnectionStringSettings =
 ConfigurationManager.ConnectionStrings("NorthwindConnection")
      Dim conn As New SqlConnection(cts.ConnectionString)
      Dim sc As New SqlCommand("
 SELECT FirstName,LastName,Address,City,PostalCode " & _
                               " FROM Employees "
 & _
                               " WHERE EmployeeID = @empId",
 conn)

      ' Add the employee ID parameter and set its value.
      sc.Parameters.Add(New SqlParameter("@empId",
 SqlDbType.Int)).Value = Int32.Parse(anID.ToString())
      Dim sdr As SqlDataReader = Nothing

      Try
         conn.Open()
         sdr = sc.ExecuteReader()

         ' This is not a while loop. It only loops once.
         If Not (sdr Is
 Nothing) AndAlso sdr.Read() Then
            ' The IEnumerable contains DataRowView objects.
            Me.aFirstName = sdr("FirstName").ToString()
            Me.aLastName = sdr("LastName").ToString()
            Me.aAddress = sdr("Address").ToString()
            Me.aCity = sdr("City").ToString()
            Me.aPostalCode = sdr("PostalCode").ToString()
         Else
            Throw New NorthwindDataException("Data
 not loaded for employee id.")
         End If
      Finally
         Try
            If Not (sdr Is
 Nothing) Then
               sdr.Close()
            End If
            conn.Close()
         Catch se As SqlException
            ' Log an event in the Application Event Log.
            Throw
         End Try
      End Try
   End Sub 'New

   Private ID As Object
   Public ReadOnly Property
 EmpID() As Object
      Get
         Return ID
      End Get
   End Property

   Private aLastName As String
   Public WriteOnly Property
 LastName() As String
      Set
         aLastName = value
      End Set
   End Property

   Private aFirstName As String
   Public WriteOnly Property
 FirstName() As String
      Set
         aFirstName = value
      End Set
   End Property

   Public ReadOnly Property
 FullName() As String
      Get
         Return aFirstName & " "
 & aLastName
      End Get
   End Property

   Private aAddress As String
   Public Property Address() As
 String
      Get
         Return aAddress
      End Get
      Set
         aAddress = value
      End Set
   End Property

   Private aCity As String
   Public Property City() As
 String
      Get
         Return aCity
      End Get
      Set
         aCity = value
      End Set
   End Property

   Private aPostalCode As String
   Public Property PostalCode() As
 String
      Get
         Return aPostalCode
      End Get
      Set
         aPostalCode = value
      End Set
   End Property

   Public Function Update() As
 Boolean

      ' Implement Update logic.
      Return True

   End Function 'Update

End Class 'NorthwindEmployee

Friend Class NorthwindDataException
   Inherits Exception

   Public Sub New(msg As
 String)
      MyBase.New(msg)
   End Sub 'New

End Class 'NorthwindDataException
End Namespace

namespace Samples.AspNet.CS {

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Web.UI;
using System.Web.UI.WebControls;
  //
  // EmployeeLogic is a stateless business object that encapsulates
  // the operations one can perform on a NorthwindEmployee object.
  //
  public class EmployeeLogic {

    // Returns a collection of NorthwindEmployee objects.
    public static ICollection GetAllEmployees
 () {
      ArrayList al = new ArrayList();

      // Use the SqlDataSource class to wrap the
      // ADO.NET code required to query the database.
      ConnectionStringSettings cts = ConfigurationManager.ConnectionStrings["NorthwindConnection"];

      SqlDataSource sds
        = new SqlDataSource(cts.ConnectionString,
                            "SELECT EmployeeID FROM Employees");
      try {
        IEnumerable IDs = sds.Select(DataSourceSelectArguments.Empty);

        // Iterate through the Enumeration and create a
        // NorthwindEmployee object for each ID.
        IEnumerator enumerator = IDs.GetEnumerator();
        while (enumerator.MoveNext()) {
          // The IEnumerable contains DataRowView objects.
          DataRowView row = enumerator.Current as DataRowView;
          string id = row["EmployeeID"].ToString();
          NorthwindEmployee nwe = new NorthwindEmployee(id);
          // Add the NorthwindEmployee object to the collection.
          al.Add(nwe);
        }
      }
      finally {
        // If anything strange happens, clean up.
        sds.Dispose();
      }

      return al;
    }

    public static NorthwindEmployee GetEmployee(object
 anID) {
      ArrayList al = GetAllEmployees() as ArrayList;
      IEnumerator enumerator = al.GetEnumerator();
      while (enumerator.MoveNext()) {
        // The IEnumerable contains initialized NorthwindEmployee objects.
        NorthwindEmployee ne = enumerator.Current as NorthwindEmployee;
        if (ne.EmpID.Equals(anID.ToString())) {
          return ne;
        }
      }
      return null;
    }
    public static void UpdateEmployee(NorthwindEmployee
 ne) {
      bool retval = ne.Update();
      if (! retval) { throw new NorthwindDataException("Employee
 update failed."); }
    }

    // This method is added as a conveniece wrapper on the original
    // implementation.
    public static void UpdateEmployeeWrapper(string
 anID,
                                             string anAddress
,
                                             string aCity,
                                             string aPostalCode)
 {
      NorthwindEmployee ne = new NorthwindEmployee(anID);
      ne.Address = anAddress;
      ne.City = aCity;
      ne.PostalCode = aPostalCode;
      UpdateEmployee(ne);
    }

    // And so on...
  }

  public class NorthwindEmployee {

    public NorthwindEmployee (object anID) {
      this.ID = anID;

      ConnectionStringSettings cts = ConfigurationManager.ConnectionStrings["NorthwindConnection"];
      SqlConnection conn = new SqlConnection (cts.ConnectionString);
      SqlCommand sc =
        new SqlCommand(" SELECT FirstName,LastName,Address,City,PostalCode
 " +
                       " FROM Employees " +
                       " WHERE EmployeeID = @empId",
                       conn);
      // Add the employee ID parameter and set its value.
      sc.Parameters.Add(new SqlParameter("@empId",SqlDbType.Int)).Value
 = Int32.Parse(anID.ToString());
      SqlDataReader sdr = null;

      try {
        conn.Open();
        sdr = sc.ExecuteReader();

        // This is not a while loop. It only loops once.
        if (sdr != null && sdr.Read())
 {
          // The IEnumerable contains DataRowView objects.
          this.firstName       = sdr["FirstName"].ToString();
          this.lastName        = sdr["LastName"].ToString();
          this.address         = sdr["Address"].ToString();
          this.city            = sdr["City"].ToString();
          this.postalCode      = sdr["PostalCode"].ToString();
        }
        else {
          throw new NorthwindDataException("Data not loaded
 for employee id.");
        }
      }
      finally {
        try {
          if (sdr != null) sdr.Close();
          conn.Close();
        }
        catch (SqlException) {
          // Log an event in the Application Event Log.
          throw;
        }
      }
    }

    private object ID;
    public object EmpID {
      get { return ID; }
    }

    private string lastName;
    public string LastName {
      set { lastName = value; }
    }

    private string firstName;
    public string FirstName {
      set { firstName = value;  }
    }

    public string FullName {
      get { return firstName + " "
 + lastName; }
    }

    private string address;
    public string Address {
      get { return address; }
      set { address = value;  }
    }

    private string city;
    public string City {
      get { return city; }
      set { city = value;  }
    }

    private string postalCode;
    public string PostalCode {
      get { return postalCode; }
      set { postalCode = value;  }
    }

    public bool Update () {

      // Implement Update logic.

      return true;
    }
  }

  internal class NorthwindDataException: Exception {
    public NorthwindDataException(string msg)
 : base (msg) { }
  }
}

package Samples.AspNet.JSL; 

import System.*;
import System.Collections.*;
import System.Configuration.*;
import System.Data.*;
import System.Data.SqlClient.*;
import System.Web.UI.*;
import System.Web.UI.WebControls.*;
   
//
// EmployeeLogic is a stateless business object that encapsulates
// the operations one can perform on a NorthwindEmployee object.
//
public class EmployeeLogic
{
    // Returns a collection of NorthwindEmployee objects.
    public static ICollection GetAllEmployees()
 throws NorthwindDataException
    {
        ArrayList al = new ArrayList();
        // Use the SqlDataSource class to wrap the
        // ADO.NET code required to query the database.
        ConnectionStringSettings cts =
            ConfigurationManager.get_ConnectionStrings().
            get_Item("NorthwindConnection");

        SqlDataSource sds = new SqlDataSource(cts.get_ConnectionString()
,
            "SELECT EmployeeID FROM Employees");
        try {
            IEnumerable ids = sds.Select(DataSourceSelectArguments.get_Empty());
            // Iterate through the Enumeration and create a
            // NorthwindEmployee object for each ID.
            IEnumerator enumerator = ids.GetEnumerator();
            while (enumerator.MoveNext()) {
                // The IEnumerable contains DataRowView objects.
                DataRowView row = (DataRowView)enumerator.get_Current();
                String idObj = row.get_Item("EmployeeID").ToString();
                NorthwindEmployee nwe = new NorthwindEmployee(idObj);
                // Add the NorthwindEmployee object to the collection.
                al.Add(nwe);
            }
        }
        finally {
            // If anything strange happens, clean up.
            sds.Dispose();
        }
        return al;
    } //GetAllEmployees

    public static NorthwindEmployee GetEmployee(Object
 anID)
        throws NorthwindDataException
    {
        ArrayList al = (ArrayList)GetAllEmployees();
        IEnumerator enumerator = al.GetEnumerator();
        while (enumerator.MoveNext()) {
            // The IEnumerable contains initialized NorthwindEmployee
 objects.
            NorthwindEmployee ne = (NorthwindEmployee)enumerator.get_Current();
            if (ne.get_EmpID().Equals(anID.ToString())) {
                return ne;
            }
        }
        return null;
    } //GetEmployee

    public static void UpdateEmployee(NorthwindEmployee
 ne)
        throws NorthwindDataException
    {
        boolean retVal = ne.Update();
        if (!(retVal)) {
            throw new NorthwindDataException("Employee update
 failed.");
        }
    } //UpdateEmployee

    // This method is added as a conveniece wrapper on the original
    // implementation.
    public static void UpdateEmployeeWrapper(String
 anID, String anAddress,
        String aCity, String aPostalCode) throws NorthwindDataException
    {
        NorthwindEmployee ne = new NorthwindEmployee(anID);
        ne.set_Address(anAddress);
        ne.set_City(aCity);
        ne.set_PostalCode(aPostalCode);
        UpdateEmployee(ne);
    } //UpdateEmployeeWrapper
    // And so on...
} //EmployeeLogic

public class NorthwindEmployee
{
    public NorthwindEmployee(Object anID) throws NorthwindDataException
    {
        this.id = anID;

        ConnectionStringSettings cts =
            ConfigurationManager.get_ConnectionStrings().
            get_Item("NorthwindConnection");
        SqlConnection conn = new SqlConnection(cts.get_ConnectionString());
        SqlCommand sc = new SqlCommand(" SELECT FirstName
,LastName,Address,"
            + "City,PostalCode " + " FROM Employees "
            + " WHERE EmployeeID = @empId", conn);
        // Add the employee ID parameter and set its value.
        sc.get_Parameters().Add(new SqlParameter("@empId",
 SqlDbType.Int)).
            set_Value(anID.ToString());
        SqlDataReader sdr = null;

        try {
            conn.Open();
            sdr = sc.ExecuteReader();
            // This is not a while loop. It only loops once.
            if (sdr != null && sdr.Read())
 {
                // The IEnumerable contains DataRowView objects.
                this.firstName = sdr.get_Item("FirstName").ToString();
                this.lastName = sdr.get_Item("LastName").ToString();
                this.address = sdr.get_Item("Address").ToString();
                this.city = sdr.get_Item("City").ToString();
                this.postalCode = sdr.get_Item("PostalCode").ToString();
            }
            else {
                throw new NorthwindDataException("Data not
 loaded for"
                    + " employee id.");
            }
        }
        finally {
            try {
                if (sdr != null) {
                    sdr.Close();
                }
                conn.Close();
            }
            catch (SqlException exp) {
                // Log an event in the Application Event Log.      
            
            }
        }
    } //NorthwindEmployee

    private Object id;

    /** @property 
     */
    public Object get_EmpID()
    {
        return id;
    } //get_EmpID

    private String lastName;

    /** @property 
     */
    public void set_LastName(String value)
    {
        lastName = value;
    } //set_LastName

    private String firstName;

    /** @property 
     */
    public void set_FirstName(String value)
    {
        firstName = value;
    } //set_FirstName

    /** @property 
     */
    public String get_FullName()
    {
        return firstName + " " + lastName;
    } //get_FullName

    private String address;

    /** @property 
     */
    public String get_Address()
    {
        return address;
    } //get_Address

    /** @property 
     */
    public void set_Address(String value)
    {
        address = value;
    } //set_Address

    private String city;

    /** @property
     */
    public String get_City()
    {
        return city;
    } //get_City

    /** @property
     */
    public void set_City(String value)
    {
        city = value;
    } //set_City

    private String postalCode;

    /** @property 
     */
    public String get_PostalCode()
    {
        return postalCode;
    } //get_PostalCode

    /** @property 
     */
    public void set_PostalCode(String value)
    {
        postalCode = value;
    } //set_PostalCode

    public boolean Update()
    {
        // Implement Update logic.
        return true;
    } //Update
} //NorthwindEmployee

public class NorthwindDataException extends
 Exception
{
    public NorthwindDataException(String msg)
    {
         super(msg);
    } //NorthwindDataException
} //NorthwindDataException