wblroles.vb

数据库学习的绝好例子简单的数据库经典入门

Public Class WBLRoles
    Implements IDisposable

    'Private variables and objects
    Private objWDARoles As WroxDataAccess.WDARoles

    Private disposed As Boolean = False

#Region " Constructor and Destructor "
    Public Sub New(ByVal Company As String, ByVal Application As String)
        objWDARoles = New WroxDataAccess.WDARoles(Company, Application)
    End Sub

    ' IDisposable
    Private Overloads Sub Dispose(ByVal disposing As Boolean)
        If Not Me.disposed Then
            If disposing Then
                ' TODO: put code to dispose managed resources
            End If

            objWDARoles.Dispose()
            objWDARoles = Nothing
        End If
        Me.disposed = True
    End Sub
#End Region

#Region " IDisposable Support "
    ' This code added by Visual Basic to correctly implement the disposable pattern.
    Public Overloads Sub Dispose() Implements IDisposable.Dispose
        ' Do not change this code.  Put cleanup code in Dispose(ByVal disposing As Boolean) above.
        Dispose(True)
        GC.SuppressFinalize(Me)
    End Sub

    Protected Overrides Sub Finalize()
        ' Do not change this code.  Put cleanup code in Dispose(ByVal disposing As Boolean) above.
        Dispose(False)
        MyBase.Finalize()
    End Sub
#End Region

#Region " Public Role Functions "
    Public Function GetNewRoleDS() As DataSet
        Try
            'Instantiate a new DataSet object
            GetNewRoleDS = New DataSet

            'Create a DataTable object
            Dim objDataTable As DataTable = GetNewRoleDS.Tables.Add("Role")

            'Create a DataColumn object
            Dim objDataColumn As DataColumn

            'Instantiate a new DataColumn and set its properties
            objDataColumn = New DataColumn("RoleID", _
                Type.GetType("System.Guid"))
            objDataColumn.AllowDBNull = False

            'Add the column to the table
            objDataTable.Columns.Add(objDataColumn)

            'Instantiate a new DataColumn and set its properties
            objDataColumn = New DataColumn("RoleName", _
                Type.GetType("System.String"))
            objDataColumn.AllowDBNull = False
            objDataColumn.MaxLength = 50

            'Add the column to the table
            objDataTable.Columns.Add(objDataColumn)

            'Instantiate a new DataColumn and set its properties
            objDataColumn = New DataColumn("RoleDescription", _
                Type.GetType("System.String"))

            'Add the column to the table
            objDataTable.Columns.Add(objDataColumn)

            'Instantiate a new DataColumn and set its properties
            objDataColumn = New DataColumn("Ranking", _
                Type.GetType("System.Byte"))
            objDataColumn.AllowDBNull = False

            'Add the column to the table
            objDataTable.Columns.Add(objDataColumn)
        Catch ExceptionErr As Exception
            Throw New System.Exception(ExceptionErr.Message, _
                ExceptionErr.InnerException)
        End Try
    End Function

    Public Function AddRole(ByVal Role As DataSet) As Boolean
        Try
            'Validate role data
            ValidateRoleData(Role)

            'Call the data component to add the new group
            Return objWDARoles.AddRole(Role)
        Catch ExceptionErr As Exception
            Throw New System.Exception(ExceptionErr.Message, _
                ExceptionErr.InnerException)
        End Try
    End Function

    Public Function GetRoles() As DataSet
        Try
            'Call the data component to get all roles
            GetRoles = objWDARoles.GetRoles
        Catch ExceptionErr As Exception
            Throw New System.Exception(ExceptionErr.Message, _
                ExceptionErr.InnerException)
        End Try
    End Function

    Public Function GetRole(ByVal RoleID As Guid) As DataSet
        Try
            'Call the data component to get a specific role
            GetRole = objWDARoles.GetRole(RoleID)
        Catch ExceptionErr As Exception
            Throw New System.Exception(ExceptionErr.Message, _
                ExceptionErr.InnerException)
        End Try
    End Function
#End Region

#Region " Private Validation Functions "
    Private Sub ValidateRoleData(ByRef Role As DataSet)
        'Validate the Name exists
        If Role.Tables("Role").Rows(0).Item( _
            "RoleName").ToString.Trim.Length = 0 Then
            Throw New System.Exception( _
                "Role Name is a required field.")
        End If

        'Validate Description value
        If Not IsDBNull(Role.Tables("Role").Rows(0).Item( _
            "RoleDescription")) Then
            If Role.Tables("Role").Rows(0).Item( _
                "RoleDescription") = String.Empty Or _
                Role.Tables("Role").Rows(0).Item( _
                "RoleDescription").ToString.Trim.Length = 0 Then
                'Set it to a null value
                Role.Tables("Role").Rows(0).Item( _
                    "RoleDescription") = DBNull.Value
            Else
                'Trim spaces
                Role.Tables("Role").Rows(0).Item("RoleDescription") = _
                    Role.Tables("Role").Rows(0).Item( _
                    "RoleDescription").ToString.Trim
            End If
        End If

        'Validate the Ranking
        If Role.Tables("Role").Rows(0).Item( _
            "Ranking") = 0 Then
            Throw New System.Exception( _
                "Ranking must contain a value between 1 and 255.")
        End If

        'Trim spaces
        Role.Tables("Role").Rows(0).Item("RoleName") = _
            Role.Tables("Role").Rows(0).Item("RoleName").ToString.Trim
    End Sub
#End Region
End Class