PowerShell fails to call a simple function from an ASP.NET DLL

Question

I'm trying to call this really simple .NET 4 function with PowerShell v2. Its definition look like:

Public Shared Function currentSchoolYear() As String Member of NM4.SiteAdmin.Logic.Subscription

Let's add the path to the DLL file containing that function. It's an ASP.NET MVC web application DLL file.

PS > Add-Type -Path C:\xxx\bin\xxxWebApp.dll

Let's try it (FAIL!):

PS >
[NM4.SiteAdmin.Logic.Subscription]::currentSchoolYear()
Exception calling "currentSchoolYear"
with "0" argument(s): "The type
initializer for
'NM4.SiteAdmin.Logic.Subscription'
threw an exception." At line:1 char:54
+ [NM4.SiteAdmin.Logic.Subscription]::currentSchoolYear
<<<< ()
+ CategoryInfo : NotSpecified: (:) [],
MethodInvocationException
+ FullyQualifiedErrorId : DotNetMethodException

Let's observe the class from PowerShell:

PS >
[NM4.SiteAdmin.Logic.Subscription]

IsPublic IsSerial Name
BaseType

-------- -------- ---- -------- True False Subscription
System.Object

Let's observe the function from PowerShell

PS >
[NM4.SiteAdmin.Logic.Subscription]::currentSchoolYear

MemberType : Method
OverloadDefinitions : {static string
currentSchoolYear()} TypeNameOfValue
:
System.Management.Automation.PSMethod
Value : static string
currentSchoolYear() Name
: currentSchoolYear IsInstance
: True

Why oh why? It seems like the doc to me.

Peter Mortensen · Accepted Answer · 2015-01-29 12:13:46Z

3

I used this command to get more details about the error:

$error | Format-List -force

Which then throwed this more precise example:

System.NullReferenceException: Object
reference not set to an instance of an
object.
at
NM4.SiteAdmin.GlobalFunctions.EstMachineProduction()
in
C:\xxx\Old_App_Code\DataModel\GlobalFunctions.vb:line
17

And I discovered it was a call to the web.config that failed:

Return
ConfigurationManager.ConnectionStrings.Item("test_DBNM4").ConnectionString

DLL files loaded by PowerShell are probably not in their usual web context. I hardcoded a ConnectionString to test it (temporary, not a good security practice), and it's working.

edited Jan 29, 2015 at 12:13

Peter Mortensen

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answered Nov 30, 2010 at 1:42

Malartre

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Comments

Serguei · Accepted Answer · 2010-11-30 00:27:30Z

0

It sounds like an exception in the static constructor OR a type on which NM4.SiteAdmin.Logic.Subscription depends could not be loaded. I'm assuming "C:\xxx\bin\xxxWebApp.dll" and friends aren't in GAC and you're not running from "C:\xxx\bin\" so therefore powershell can't resolve the dependencies. Try running this from "C:\xxx\bin\".

answered Nov 30, 2010 at 0:27

Serguei

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