projtimecardexpenses.cls

VB中实现3层结构的完整教学示例（很难得的）

VERSION 1.0 CLASS
Begin
  MultiUse = -1  'True
  Persistable = 0  'NotPersistable
  DataBindingBehavior = 0  'vbNone  
  DataSourceBehavior = 0   'vbNone
  MTSTransactionMode = 0   'NotAnMTSObject
End
Attribute VB_Name = "ProjTimeCardExpenses"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = True
Attribute VB_Ext_KEY = "SavedWithClassBuilder", "Yes"
Attribute VB_Ext_KEY = "SavedWithClassBuilder6", "Yes"
Attribute VB_Ext_KEY = "SavedWithCOMExpress", "Yes"
Attribute VB_Ext_KEY = "Collection" ,"ProjTimeCardExpense"
Attribute VB_Ext_KEY = "Member0" ,"ProjTimeCardExpense"
Attribute VB_Ext_KEY = "Top_Level", "No"
Option Explicit  
Implements COMEXDataSource
Private m_Fields() 
Private mcol As Collection

Public Event OnRecordInsert(ByRef vProjTimeCardExpense As ProjTimeCardExpense)

Public Property Get Item(vntIndexKey As Variant) As ProjTimeCardExpense
Attribute Item.VB_UserMemId = 0
  On Error Resume Next
  Set Item = mCol(vntIndexKey)
  If Err.Number <> 0 Then
    Set Item = Nothing
  End If
End Property

Public Function Key(ByRef vProjTimeCardExpense As ProjTimeCardExpense) As String
  Key = ":" & vProjTimeCardExpense.TimeCardExpenseID 
End Function

Public Property Get Count() As Long
  Count = mCol.Count
End Property

Public Property Get NewEnum() As IUnknown
Attribute NewEnum.VB_UserMemId = -4
Attribute NewEnum.VB_MemberFlags = "40"
  Set NewEnum = mCol.[_NewEnum]
End Property

Private Sub Class_Initialize()
  Set mCol = New Collection 
  m_Fields = Array("ExpenseAmount", "ExpenseCodeID", "ExpenseDescription", "ProjectID", "TimeCardExpenseID", "TimeCardID", "ExpenseDate")
End Sub

Private Sub Class_Terminate()
  Set mCol = Nothing
End Sub

Public Sub Remove(vntIndexKey As Variant)
  mCol.Remove vntIndexKey
End Sub

Public Sub Clear()
  Set mCol = Nothing
  Set mCol = New Collection
End Sub

Public Function AddExisting(vProjTimeCardExpense As ProjTimeCardExpense, Optional sKey As String = vbNullString) As Boolean
  On Error GoTo Err_AddExisting
  If Len(sKey) = 0 Then
    mCol.Add vProjTimeCardExpense
  Else
    mCol.Add vProjTimeCardExpense, sKey
  End If
  AddExisting = True
  RaiseEvent OnRecordInsert(vProjTimeCardExpense)
  Exit Function
Err_AddExisting:
  AddExisting = False
End Function

Public Function Add(m_ExpenseAmount As Currency, m_ExpenseCodeID As Long, m_ExpenseDescription As String, m_ProjectID As Long, m_TimeCardExpenseID As Long, m_TimeCardID As Long, m_ExpenseDate As Date, Optional sKey As String = vbNullString) As ProjTimeCardExpense
  Dim objNewMember As ProjTimeCardExpense
  Set objNewMember = New ProjTimeCardExpense
  objNewMember.ExpenseAmount = m_ExpenseAmount
  objNewMember.ExpenseCodeID = m_ExpenseCodeID
  objNewMember.ExpenseDescription = m_ExpenseDescription
  objNewMember.ProjectID = m_ProjectID
  objNewMember.TimeCardExpenseID = m_TimeCardExpenseID
  objNewMember.TimeCardID = m_TimeCardID
  objNewMember.ExpenseDate = m_ExpenseDate

  If Len(sKey) = 0 Then
    mCol.Add objNewMember
  Else
    mCol.Add objNewMember, sKey
  End If
  Set Add = objNewMember
  RaiseEvent OnRecordInsert(objNewMember)
  Set objNewMember = Nothing
End Function


Public Function LoadRelated(ProjectID As Long, Optional ByVal SQLWhereClause As String = "") As Boolean
  Dim adoRS As New ADODB.Recordset
  Dim strSQL As String
  Dim uProjTimeCardExpense As New ProjTimeCardExpense
  On Error GoTo Err_LoadRelated

  Screen.MousePointer = vbHourglass

  Clear

  strSQL = "Select a.ExpenseAmount,a.ExpenseCodeID,b.ExpenseCode As ExpenseCode,a.ExpenseDescription,a.ProjectID,c.ProjectName As ProjectName,a.TimeCardExpenseID,a.TimeCardID,d.DateEntered As DateEntered,a.ExpenseDate From (([Time Card Expenses] a LEFT JOIN [Expense Codes] b ON a.ExpenseCodeID = b.ExpenseCodeID) LEFT JOIN Projects c ON a.ProjectID = c.ProjectID) LEFT JOIN [Time Cards] d ON a.TimeCardID = d.TimeCardID WHERE a.ProjectID = " & ProjectID & ""
  If SQLWhereClause <> "" Then
    If UCase(Trim(Left$(SQLWhereClause, 5))) = "WHERE" Then
      SQLWhereClause = Replace(UCase(SQLWhereClause), "WHERE ", "AND ")
    Else
      If UCase(Trim(Left$(SQLWhereClause, 3))) <> "AND" Then
        SQLWhereClause = "AND " & SQLWhereClause
      End If
    End If
  End If
  strSQL = strSQL & " " & SQLWhereClause

  adoRS.CacheSize = 250
  adoRS.Open strSQL, Conn, adOpenForwardOnly, adLockReadOnly
  With adoRS
    Do While Not .EOF
      Set uProjTimeCardExpense = Nothing
      Set uProjTimeCardExpense = New ProjTimeCardExpense
      uProjTimeCardExpense.ExpenseAmount= IIF(IsNull(adoRS("ExpenseAmount")), 0, adoRS("ExpenseAmount"))
      uProjTimeCardExpense.ExpenseCodeID= IIF(IsNull(adoRS("ExpenseCodeID")), 0, adoRS("ExpenseCodeID"))
      uProjTimeCardExpense.ExpenseCode= IIF(IsNull(adoRS("ExpenseCode")), "", adoRS("ExpenseCode"))
      uProjTimeCardExpense.ExpenseDescription= IIF(IsNull(adoRS("ExpenseDescription")), "", adoRS("ExpenseDescription"))
      uProjTimeCardExpense.ProjectID= IIF(IsNull(adoRS("ProjectID")), 0, adoRS("ProjectID"))
      uProjTimeCardExpense.ProjectName= IIF(IsNull(adoRS("ProjectName")), "", adoRS("ProjectName"))
      uProjTimeCardExpense.TimeCardExpenseID= IIF(IsNull(adoRS("TimeCardExpenseID")), 0, adoRS("TimeCardExpenseID"))
      uProjTimeCardExpense.TimeCardID= IIF(IsNull(adoRS("TimeCardID")), 0, adoRS("TimeCardID"))
      uProjTimeCardExpense.DateEntered= IIF(IsNull(adoRS("DateEntered")), "12:00:00AM", adoRS("DateEntered"))
      uProjTimeCardExpense.ExpenseDate= IIF(IsNull(adoRS("ExpenseDate")), "12:00:00AM", adoRS("ExpenseDate"))
      uProjTimeCardExpense.OldTimeCardExpenseID = uProjTimeCardExpense.TimeCardExpenseID

      uProjTimeCardExpense.IsDirty = False
      mcol.Add uProjTimeCardExpense, ":" & uProjTimeCardExpense.TimeCardExpenseID 

      .MoveNext
    Loop
    .Close
  End With
    
  LoadRelated = True
Done_LoadRelated:
  Screen.MousePointer = vbDefault
  Exit Function

Err_LoadRelated:
  ErrNum = Err.Number
  ErrMsg = Err.Description
  Call ErrHandler(ErrNum, ErrMsg,"ProjTimeCardExpenses","GetMultiRecords")
  Resume Done_LoadRelated 
End Function

Friend Sub Delete()
	Dim uProjTimeCardExpense As ProjTimeCardExpense
  For Each uProjTimeCardExpense In mCol
    uProjTimeCardExpense.Delete
  Next
End Sub
 

Private Function COMEXDataSource_GetData(ByVal Field As Long, ByVal Record As Long) As Variant 
  If Record > 0 And Record <= mcol.Count Then
    Dim vItem As COMEXDataSourceSingle
    Set vItem = mcol.Item(Record)
    COMEXDataSource_GetData = vItem.GetData(Field)
  Else
    COMEXDataSource_GetData = Null
  End If
End Function

Private Function COMEXDataSource_GetFieldCount() As Long
  COMEXDataSource_GetFieldCount =  UBound(m_Fields) + 1
End Function

Private Function COMEXDataSource_GetFieldName(ByVal Field As Long) As String
  If Field > 0 AND Field <= UBound(m_Fields) + 1 Then 
    COMEXDataSource_GetFieldName = m_Fields(Field - 1)
  End If
End Function

Private Function COMEXDataSource_GetRecordCount() As Long
  COMEXDataSource_GetRecordCount = mcol.Count
End Function

Private Sub COMEXDataSource_SetData(ByVal Field As Long, ByVal Record As Long, ByVal newData As Variant)
  Dim vItem As COMEXDataSourceSingle
  If Record > 0 And Record <= mcol.Count  Then    
    Set vItem = mcol.Item(Record)
    vItem.SetData Field, newData 
  ElseIf Record = mcol.count + 1 Then
    Set vItem = New ProjTimeCardExpense
    vItem.SetData Field, newData 
    mcol.Add vItem    
  End If
End Sub 

Private Sub COMEXDataSource_Delete(ByVal Record As Long)
  If Record > 0 And Record <= mcol.Count Then mcol.Item(Record).Delete  
End Sub

Private Function COMEXDataSource_Save() As Boolean
  Dim vItem As ProjTimeCardExpense, i As long, bolRet As Boolean  
  i = 1
  Do While i <= mcol.count
    Set vItem = mcol.Item(i)    
    If Not (vItem.IsNew and vItem.IsDeleted) Then 
      bolRet = vItem.Save
      If Not bolRet Then 
        COMEXDataSource_Save = False
        Exit Function
      End If                
      i = i + 1
    Else
      mcol.remove i
    End If
  Loop
  COMEXDataSource_Save = True  
End Function 

Private Property Get COMEXDataSource_IsDeleted(ByVal Record As Long) As Boolean
  If Record > 0 And Record <= mcol.Count Then  _
    COMEXDataSource_IsDeleted = Item(Record).IsDeleted
End Property