System.Type.GetType from across assemblies / namespaces

Question

Hi,

I'm writing a reflection module where I'm storing all reflection related methods.  I would like to move this module into a different assembly (and namespace) but the functions cease to work.

I will paste the method in its entirety bellow, as well as some sample code.

The statement that fails, however, is the following

generic = System.Type.GetType(objectName, True, True).MakeGenericType(types_for_Generic)

In this case, the "ObjectName" refers to a generic type in another assembly, and "Types_for_Generic" refers to type contained in the SAME assembly
as the Reflection Functions.

If I move the Reflection module back into the main project, it works again!

ex:
Project: MyLibrary

namespace: MyLibrary

Public Module ReflectionHelpers

    '''The following method provodies for the creation of Objects with support for generics

    Public Function CreateObject(ByVal name As String, Optional ByVal types_for_Generic As Type() = Nothing) As Object
        Dim objectName As String
        Dim generic As Type
        Try
            If Not types_for_Generic Is Nothing Then
                objectName = name & "`" & types_for_Generic.Length
                generic = System.Type.GetType(objectName).MakeGenericType(types_for_Generic)
            Else
                generic = System.Type.GetType(name)
            End If


            If generic Is Nothing Then
                Return generic
            Else : Return (Activator.CreateInstance(generic))
            End If
        Catch ex As Exception
            Throw New Exception("Failed to instantiate object " & name, ex)
        End Try

    End Function

End Module


Public Class AClassInMyLibrary

    Public data As String = "foo"
End Class

Project: TestApp
Namespace: TestAppApplication

Public Class TestReflection

    Private Function GetReportTest(ByVal reportName As String, ByVal propNames As List(Of String), ByVal srcType As Type) As Object
        Dim reportClass As Object = ReflectionModule.CreateObject(GetFullyQualifiedName(reportName), New Type() {srcType})
        Dim controller As Object = reportClass.GenerateReportController(propNames)
        Return controller
    End Function

    Private Function GetFullyQualifiedName(ByVal className As String) As String
        Return Me.GetType.Namespace & "." & className
    End Function
End Class

The CreateObject call receives

"TestAppApplication.Report1" and the type  MyLibrary.AClassInMyLibrary

I came across a few other posts like this one
http://social.msdn.microsoft.com/Forums/en-US/netfxbcl/thread/6928930c-54b4-45bf-a0d0-ecc15c89d570/?prof=required&wa=wsignin1.0

but they did not cover my particular issue with GetType on a generic.

Any help is greatly appreciated.

Answer 1

There are a few unknowns here....

1. Can we see the class definition of TestAppApplication.Report1.
2. What is the exact error and stack trace.  ("ceases to work" is a bit vague).
3. Are you able to at least perform the GetType portion without the MakeGenericType? (The stack trace should help you determine that)

---

Coding Light - Illuminated Ideas and Algorithms in Software
Coding Light Wiki • LinkedIn • ForumsBrowser

Answer 2

Hi David,

Sorry, should have included the error/stack trace.  I really appreciate the help.  I'm going to answer your questions a little out of order. 

Question 3:

I tried ReflectionModule.CreateObject with a non-generic.  The failure is that  System.Type.GetType(objectName, True, True) fails to generate a type and returns null (or throws an exception if param 2 = True.).  Because of this ".MakeGenericType(...)" is never reached.



Question 2:

I tried to simplify the code example to avoid pasting a hundred lines of code.  As a result I should probably explain the stack error & trace a little.

The stack trace for

generic = System.Type.GetType(objectName,

True, True).MakeGenericType(types_for_Generic)

is as follows:

The references "TransactionManagerApplication" which in my original post was represented by TestAppApplication.

The "TMServiceLib" is represented by "MyLibrary" in my simplified example.

Basically the reflection call is looking within its own assembly, and not the TestAppApplication.

Error Msg:

Could not load type 'TransactionManagerApplication.CurrencyExposure`1' from assembly 'TMServiceLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.

Stack Trace:

   at System.RuntimeTypeHandle._GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, Boolean loadTypeFromPartialName)
   at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark)
   at System.RuntimeType.PrivateGetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark)
   at System.Type.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase)
   at TMServiceLib.ReflectionModule.CreateObject(String name, Type[] types_for_Generic)


Question 1

I have multiple "Report" classes so I'll just paste on of them below.  This is located in the TransactionManagerApplication project & namespace

Public Class CurrencyExposure(Of ItemType)
    Implements iGenerateReportController(Of ItemType)

    Public Function GenerateReportController(ByVal propNames As List(Of String)) As ReportDataController(Of ItemType) Implements iGenerateReportController(Of ItemType).GenerateReportController
        Dim res As New ReportDataController(Of ItemType)

        Dim ObjPropropLst As New List(Of ObjectPropertyStringAndFormatCode)
        ObjPropropLst.Add(New ObjectPropertyStringAndFormatCode(propNames.Item(0), "", "Currency"))
        ObjPropropLst.Add(New ObjectPropertyStringAndFormatCode(propNames.Item(1), "C2", "Market Value"))
        ObjPropropLst.Add(New ObjectPropertyStringAndFormatCode(propNames.Item(2), "P2", "% Assets"))

        res.PropertyAndFormatList = ObjPropropLst.ToArray

        'Format the cells
        For i As Integer = 0 To res.PropertyAndFormatList.Length - 1
            res.FormatTemplateByColumn(i).Size = "8pt"
            res.FormatTemplateByColumn(i).Weight = RDLCFont_Weight.f_Medium
        Next

        res.GroupByTemplate.Weight = RDLCFont_Weight.h_Bold
        res.GroupFooterFormatTemplate.Size = "8pt"
        res.GroupFooterFormatTemplate.Weight = RDLCFont_Weight.e_Normal
        res.GroupFooterFormatTemplate.Style = RDLCFont_Style.Italic
        res.HeaderFormatTemplate.Weight = RDLCFont_Weight.h_Bold
        res.HeaderFormatTemplate.Size = "8pt"

        Return res
    End Function

End Class

Answer 3

You'll have to specify the assembly name:

'TransactionManagerApplication.CurrencyExposure`1, TransactionManagerApplication'

Is the string that should be used to resolve this type.  Note the assembly name appended at the end, following the comma.

---

Coding Light - Illuminated Ideas and Algorithms in Software
Coding Light Wiki • LinkedIn • ForumsBrowser

Answer 4

Thank you David, you're a life saver!!!
I spent way to much time trying to figure that out . . . and of course the solution was so simple.