Question

我有一个这样的课程：

Public Class ClassPermissions

    Public Class Configuration
        Public Const EditPermissions As String = "[Edit Permissions]"
        Public Const OpenConfigPanel As String = "[Open Configuration Panel]"
    End Class

    Public Class Access
        Public Const AccessCarForm As String = "[Access Car Form]"
        Public Const AccessCarList As String = "[Access Car List]"
    End Class

    ''' <summary>
    ''' Verifies permission for the logged on user
    ''' </summary>
    ''' <param name="permissao">Permission Required, ClassPermissions.(...)</param>
    ''' <returns>True if user has permission</returns>
    ''' <remarks></remarks>
    Public Shared Function HasPermission(permission As String) As Boolean
        Dim ret As Boolean = False
        Dim sqlQuery As String = ""
        Dim dt As DataTable

        sqlQuery = "SELECT P." & permission & " FROM Permissions AS P INNER JOIN Users AS C ON P.idUser = C.UserID AND C.UserID = " & vggLoggedUserID & " AND C.Active = 1"
        dt = GetGenericDataTable(sqlQuery, "Permission")

        If dt.Rows.Count > 0 AndAlso dt.Rows(0)(0) = "True" Then
            ret = True
        End If

        Return ret
    End Function
End Class

我怎么能说'HasPermission'函数的参数'permission'只能是在Class ClassPermissions里面的类中声明的常量？

我想要的是，当某人编码并写入'ClassPermissions.HasPermission（'然后它会显示一个常量列表，这种情况是'EditPermissions'，'OpenConfigPanel'，'AccessCarForm'和'AccessCarList'。

Answer 1

将数据库中的实际列名称作为字符串常量公开可能是个坏主意。

声明一个枚举：

Public Enum Configuration
  EditPermissions
  OpenConfigPanel 
End Enum

将您的方法更改为

Public Shared Function HasPermission(permission As Configuration) As Boolean

在方法内部，确保在枚举中定义permission并将其映射到相应的字符串值。例如。拥有可能值为Private Dictionary(Of Configuration, String)并使用TryGetValue()。

VB.Net Parameter作为另一个类中的一个类内的常量

1 个答案: