オブジェクトバインディングに関するヒントとテクニック

Private _LastName As String
Public Property LastName() As String
   Get
      Return _LastName
   End Get
   Set(ByVal value As String)
      _LastName = value
   End Set
End Property

private string _LastName;
public string LastName
{
   get { return _LastName;}
   set { _LastName = value;}
}

Private Function Retrieve(ByVal CustomerID As Int32) As DataRow
Dim dt As New DataTable
   ’ Define the columns
   dt.Columns.Add("CustomerID")
   dt.Columns.Add("LastName")
   dt.Columns.Add("FirstName")
   Select Case CustomerID
   Case 1
      dt.Rows.Add(1, "Einstein", "Albert")
   Case 2
      dt.Rows.Add(2, "Curie", "Marie")
   Case 3
      dt.Rows.Add(3, "Brahe", "Tycho")
   Case 4
      dt.Rows.Add(4, "Faraday", "Michael")
   End Select
   Return dt.Rows(0)
End Function

private DataRow Retrieve(Int32 CustomerID)
{
   DataTable dt = new DataTable();
   // Define the columns
   dt.Columns.Add("CustomerID");
   dt.Columns.Add("LastName");
   dt.Columns.Add("FirstName");
   switch (CustomerID)
   {
      case 1:
         dt.Rows.Add(1, "Einstein", "Albert");
         break;
      case 2:
         dt.Rows.Add(2, "Curie", "Marie");
         break;
      case 3:
         dt.Rows.Add(3, "Brahe", "Tycho");
         break;
      case 4:
         dt.Rows.Add(4, "Faraday", "Michael");
         break;
   }
   return dt.Rows[0];
}

Private Sub New()
’ Don’t allow creation of this object
End Sub
Public Shared Function Create(ByVal CustomerID _
   As Int32) As Customer
   ’ Create the customer
   Dim oCustomer As New Customer
   ’ Retrieve the data for this customer
   Dim dr As DataRow
   dr = oCustomer.Retrieve(CustomerID)
   ’ Populate the business object
   oCustomer.Populate(dr)
   Return oCustomer
End Function

private Customer()
{
   // Don’t allow creation of this object
}
public static Customer Create(Int32 CustomerID)
{
   // Create the customer
   Customer oCustomer = new Customer();
   // Retrieve the data for this customer
   DataRow dr =oCustomer.Retrieve(CustomerID);
   // Populate the business object
   oCustomer.Populate(dr);
   return oCustomer;
}

Private Sub Populate(ByVal CustomerDataRow As _
   DataRow)
   With CustomerDataRow
      Me.LastName = .Item("LastName").ToString
      Me.FirstName = .Item("FirstName").ToString
      Me.CustomerID = .Item("CustomerID").ToString
   End With
End Sub

private void Populate(DataRow CustomerDataRow)
{
   this.LastName =
      CustomerDataRow["LastName"].ToString();
   this.FirstName =
      CustomerDataRow["FirstName"].ToString();
   this.CustomerID =
   Convert.ToInt32(CustomerDataRow["CustomerID"]);
}

Private Sub CustomerWin_Load(ByVal sender As _
   Object, ByVal e As System.EventArgs) _
   Handles Me.Load
   Dim CustomerInstance As Customer
      CustomerInstance = Customer.Create(1)
      CustomerBindingSource.DataSource =
         CustomerInstance
End Sub

private void CustomerWin_Load(object sender,
   EventArgs e)
{
   Customer CustomerInstance =
      Customer.Create(1);
   customerBindingSource.DataSource =
      CustomerInstance;
}

Public Property LastName() As String
   Get
      Return _LastName
   End Get
   Set(ByVal value As String)
      If String.IsNullOrEmpty(value) Then
         Throw New Exception( _
            "The Last Name cannot be empty")
      End If
      _LastName = value
   End Set
End Property

public string LastName
{
   get { return _LastName;}
   set
   {
      if (String.IsNullOrEmpty(value))
      {
         throw new Exception(
            "The Last Name cannot be empty");
      }
      _LastName = value;
   }
}

Public Enum EntityStateEnum
   Unchanged
   Added
   Deleted
   Modified
End Enum

public enum EntityStateEnum
{
   Unchanged,
   Added,
   Deleted,
   Modified,
}

Private _EntityState As EntityStateEnum
Public Property EntityState() As EntityStateEnum
   Get
      Return _EntityState
   End Get
   Private Set(ByVal value As EntityStateEnum)
      _EntityState = value
   End Set
End Property

private EntityStateEnum _EntityState;
public EntityStateEnum EntityState
{
   get { return _EntityState; }
   private set { _EntityState = value; }
}

Public Class Customer
   Implements INotifyPropertyChanged
   Public Event PropertyChanged(ByVal sender As _
     Object, ByVal e As PropertyChangedEventArgs) _
     Implements INotifyPropertyChanged.PropertyChanged

class Customer : INotifyPropertyChanged
public event PropertyChangedEventHandler
   PropertyChanged;

Private Sub DataStateChanged(ByVal dataState As _
   EntityStateEnum, ByVal propertyName As String)
   ’ Raise the event
   If Not String.IsNullOrEmpty(propertyName) Then
      RaiseEvent PropertyChanged(Me, _
         New PropertyChangedEventArgs(propertyName))
   End If
   ’ If the state is deleted, mark it as deleted
   If dataState = EntityStateEnum.Deleted Then
      Me.EntityState = dataState
   End If
   If Me.EntityState = EntityStateEnum.Unchanged Then
      Me.EntityState = dataState
   End If
End Sub

private void DataStateChanged(EntityStateEnum
   dataState, string propertyName)
{
   // Raise the event
   if (PropertyChanged != null &&
      propertyName != null)
   {
      PropertyChanged(this, new
         PropertyChangedEventArgs(propertyName));
   }
   // If the state is deleted, mark it as deleted
   if (dataState == EntityStateEnum.Deleted)
   {
      this.EntityState = dataState;
   }
   if (this.EntityState ==
      EntityStateEnum.Unchanged)
   {
      this.EntityState = dataState;
   }
}

Public Property LastName() As String
   Get
      Return _LastName
   End Get
   Set (ByVal value as String)
      If String.IsNullOrEmpty(value) Then
         Throw New Exception( _
            "The Last Name cannot be empty")
      End If
      If value <> _LastName Then
         Me.DataStateChanged( _
            EntityStateEnum.Modified, _
            "LastName")
      End If
      _LastName = value
   End Set
End Property

public string LastName
{
   get { return _LastName;}
   set
   {
      if (String.IsNullOrEmpty(value))
      {
         throw new Exception(
            "The Last Name cannot be empty");
      }
      if (value != _LastName)
      {
         this.DataStateChanged(
            EntityStateEnum.Modified,
            "LastName");
      }
      _LastName = value;
   }
}

Public ReadOnly Property IsDirty() As Boolean
   Get
      Return Me.EntityState <> _
         EntityStateEnum.Unchanged
   End Get
End Property

public Boolean IsDirty
{
   get{ return
      this.EntityState!=EntityStateEnum.Unchanged;}
}

Public Class PurchasedItemCollection
Inherits BindingList(Of PurchasedItem)

class PurchasedItemCollection :
   BindingList<PurchasedItem>

Public Shared Function Create(ByVal CustomerID _
   As Int32) As PurchasedItemCollection
   Dim oCollection As New PurchasedItemCollection
   Dim dt As DataTable
   ’ Perform the appropriate retrieve
   dt = oCollection.Retrieve(CustomerID)
   ’ For each row, create an object in the list
   For Each dr As DataRow In dt.Rows
      Dim oItem As PurchasedItem
      oItem = PurchasedItem.Create(dr)
      oCollection.Add(oItem)
   Next
   Return oCollection
End Function

public static PurchasedItemCollection Create(
   Int32 CustomerID)
{
   PurchasedItemCollection oCollection =
      new PurchasedItemCollection();
   // Perform the appropriate retrieve
   DataTable dt =
      oCollection.Retrieve(CustomerID);
   // For each row, create an object in the list
   foreach (DataRow dr in dt.Rows)
   {
      PurchasedItem oItem =
         PurchasedItem.Create(dr);
      oCollection.Add(oItem);
   }
   return oCollection;
}

Private Sub CustomerWin_Load(ByVal sender As _
   Object, ByVal e As System.EventArgs) _
   Handles Me.Load
   Dim CustomerInstance As Customer
   CustomerInstance = Customer.Create(1)
   CustomerBindingSource.DataSource = _
      CustomerInstance
   Dim ItemCollection As PurchasedItemCollection
   ItemCollection = _
      PurchasedItemCollection.Create(1)
   PurchasedItemCollectionBindingSource. _
      DataSource = ItemCollection
End Sub

private void CustomerWin_Load(object sender,
   EventArgs e)
{
   Customer CustomerInstance =
      Customer.Create(1);
   customerBindingSource.DataSource =
      CustomerInstance;
   PurchasedItemCollection ItemCollection =
      PurchasedItemCollection.Create(1);
   purchasedItemCollectionBindingSource.
      DataSource = ItemCollection;
}

Public Class CustomerList
   Public ReadOnly Property FullName() As String
      Get
         Return ""
      End Get
   End Property
   Public ReadOnly Property CustomerID() As Int32
      Get
         Return 0
      End Get
   End Property
   Public ReadOnly Property CustomerDataTable() As DataTable
      Get
         Return Retrieve()
      End Get
   End Property
   Private Function Retrieve() As DataTable
      Dim dt As New DataTable
      dt.Columns.Add("FullName")
      dt.Columns.Add("CustomerID")
      dt.Rows.Add("Einstein, Albert", 1)
      dt.Rows.Add("Curie, Marie", 2)
      dt.Rows.Add("Brahe, Tycho", 3)
      dt.Rows.Add("Faraday, Michael", 4)
      Return dt
   End Function
End Class

class CustomerList
{
   public string FullName
   {
      get { return "";}
   }
   public Int32 CustomerID
   {
      get { return 0;}
   }
   public DataTable CustomerDataTable
   {
      get { return Retrieve();}
   }
   private DataTable Retrieve()
   {
      DataTable dt = new DataTable();
      dt.Columns.Add("FullName");
      dt.Columns.Add("CustomerID");
      dt.Rows.Add("Einstein, Albert", 1);
      dt.Rows.Add("Curie, Marie", 2);
      dt.Rows.Add("Brahe, Tycho", 3);
      dt.Rows.Add("Faraday, Michael", 4);
      return dt;
   }
}

Private Sub CustomerWin_Load(ByVal sender As _
   Object, ByVal e As System.EventArgs) _
   Handles Me.Load
   ’ Bind the list
   Dim oList As New CustomerList
   CustomerListBindingSource.DataSource = _
      oList.CustomerDataTable
End Sub
Private Sub _
   FullNameComboBox_SelectionChangeCommitted( _
   ByVal sender As Object, _
   ByVal e As System.EventArgs) _
   Handles FullNameComboBox.SelectionChangeCommitted
   Dim oCustomer As Customer
   oCustomer = Customer.Create(
      FullNameComboBox.SelectedValue)
   CustomerBindingSource.DataSource = oCustomer
   Dim oCollection As PurchasedItemCollection
   oCollection = PurchasedItemCollection.Create( _
      FullNameComboBox.SelectedValue)
   PurchasedItemCollectionBindingSource. _
      DataSource = oCollection
End Sub

private void CustomerWin_Load(object sender,
   EventArgs e)
{
   CustomerList oList = new CustomerList();
   customerListBindingSource.DataSource =
      oList.CustomerDataTable;
}
private void
   fullNameComboBox_SelectionChangeCommitted(
      object sender, EventArgs e)
{
   Int32 selectedID = Convert.ToInt32(
      fullNameComboBox.SelectedValue);
   Customer oCustomer =
      Customer.Create(selectedID);
   customerBindingSource.DataSource =
      oCustomer;
   PurchasedItemCollection oCollection =
      PurchasedItemCollection.Create(selectedID);
   purchasedItemCollectionBindingSource.
      DataSource = oCollection;
}