VB.Net 搜索泛型类型的命名空间（反射）

Question

我正在尝试使用上下文动态注册实体和配置（仅限 ef4 代码）

我通常会这样做：

Private Shared Sub ConfigureDatabase(ByRef Builder As ContextBuilder(Of ContextExtension))
  'Load configurations for each of the tables (Entity sets) in our database...
  ConfigureEntity(Builder, New ContactConfig)
End Sub

 Private Shared Sub ConfigureEntity(Of T)(ByRef Builder As ContextBuilder(Of ContextExtension), ByVal config As EntityConfiguration(Of T), ByVal setName As String)
    'Register the entity configuration with the builder
    Builder.Configurations.Add(config)

    'Register the entity set name with the builder
    Builder.RegisterSet(Of T)(setName)
End Sub

其中ContactConfig 是继承EntityConfiguration(Of Contact) 的类，Contact 是实现接口IEntity 的类（IEntity 是所有实体通用的）。

所以...我需要在命名空间（比如 Project.DB.Client）中搜索所有匹配的签名：

EntityConfiguration(Of <Class which implements IEntity>)

我怎样才能做到这一点？

Answer 1

命名空间只是对象名称的一部分。搜索继承泛型类的类型比仅按命名空间名称过滤要付出更多的努力：

Private Function CheckType(ByVal type As Type) As Boolean
    If (type Is GetType(Object)) Then ' object hierarhy root reached'
        Return False
    End If
    If (type.IsGenericType) Then
        ' inherits from some generic type'
        Dim parameters = type.GetGenericArguments()
        ' check if it has generic 1 parameter'
        If parameters.Length = 1 Then
            ' check if generic parameter is defined'
            If Not (parameters(0).FullName Is Nothing) Then
                ' check if parameter implements IEntity'
                If GetType(IEntity).IsAssignableFrom(parameters(0)) Then
                    ' check if it is EntityConfiguration(Of T)'
                    If type Is GetType(EntityConfiguration(Of )).MakeGenericType(parameters) Then
                        Return True
                    End If
                End If
            End If
        End If
    End If
    Return CheckType(type.BaseType)
End Function

Function FilterTypes(ByVal nameSpaceName As String, ByVal types As IEnumerable(Of Type)) As List(Of Type)
    Dim result As New List(Of Type)
    ' append . to namespace name'
    nameSpaceName = nameSpaceName + "."
    For Each type As Type In types
        ' we do not need abstract classes, wont be able to create their instances anyway'
        If (type.IsClass And Not type.IsAbstract And
             type.FullName.StartsWith(nameSpaceName)) Then
            ' check if type is inherited from EntityConfiguration(Of T)'
            If (CheckType(type)) Then
                result.Add(type)
            End If
        End If
    Next
    Return result
End Function

CheckType 函数检查类型是否继承自 EntityConfiguration(Of T)。

FilterTypes 函数还通过命名空间过滤类型并返回过滤列表结果。

例如：Dim types = FilterTypes("Project.DB.Client", Assembly.GetExecutingAssembly().GetTypes())。