Access to private method using reflection in C#/Silverlight applications

Question

My code invokes method using reflection:

        scoringType.InvokeMember("scoringClient_ScorePostsCompleted",
            BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.NonPublic,
            null, scoringInstance,
            new object[] { sArg, eArg });

where scoringInstance is an instance of a ModelView class. The method is private, but I use BindingFlags.NonPublic, so, i should be able to access it, but I cannot - I get MethodAccessException exception: "Attempt by method ... to access method ... failed." Google doesnt seem to have an answer. Do you have any idea how to fix it by any chance?

Review the ReflectionPermission class. – Hans Passant Sep 01 '11 at 22:09 — Hans Passant, Sep 01 '11 at 22:09

MerickOWA · Accepted Answer · 2012-01-27T15:32:56.770

11

From MSDN on silverlight

In Silverlight, you cannot use reflection to access private types and members. If the access level of a type or member would prevent you from accessing it in statically compiled code, you cannot access it dynamically by using reflection.

Edit:

Silverlight 5 now does allow for reflection of private members ONLY if you're running with elevated privileges either out-of-browser or in-browser (in-browser using the generated test page DOES NOT WORK).

edited Jan 27 '12 at 15:32

answered Sep 01 '11 at 22:09

MerickOWA

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Thanks! You saved me hours of failed attempts :) – Val Sep 02 '11 at 18:07
@MerickOWA, any workaround? any way to trust my apps? `Reflection.Emit`? – Shimmy Weitzhandler Jan 27 '12 at 10:02
@Shimmy I did some more testing and the only work around is to use Silverlight 5 with elevated privileges either in-browers or out-of-browser. Silverlight 4 elevated privileges does not allow reflection. I'll update the answer to reflect this since Silverlight 5 has been released. – MerickOWA Jan 27 '12 at 15:28
I'm on SL 5. I'll make a research on elevated trusts. – Shimmy Weitzhandler Jan 28 '12 at 20:33
Just FYI, the ability to get at private members with elevated privileges is buggy on Mac OSX. I've had to work around an issue where code in a leaf class *can* access the private member but the exact same code in the leaf's parent cannot... it is bizarre. – aggieNick02 Jun 18 '13 at 14:36
@MerickOWA. Hi Merick, I am trying to access an internal member on ManualResetEvent class (SafeWaitHandle) but I get FIeldAccessException. I am running SL5 with elevated permissions. What exactly did you mean by "DOES NOT WORK in-browser using generated test page"? I replaced the webpage with a new one and made that as the startup page but it is till the same. Can you provide more information. Thx – user559788 Nov 20 '13 at 05:32
@user559788 just what it says, it wont work. You need to associate your silverlight application with a local asp.net website project, and launch the website instead. – MerickOWA Nov 20 '13 at 19:02

score 3 · Answer 2 · answered Mar 21 '13 at 16:08

3

If you need access to non-public members, you can do this using the LambdaExpression. I wrote this article that explains in detail why it works.

answered Mar 21 '13 at 16:08

Vyacheslav Volkov

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LamdaExpression doesn't work for SL 5 .NET internal methods marked with SecuritySafeCriticalAttribute. Have you tested your solution? – yar_shukan Aug 21 '14 at 14:07
Unfortunately, this solution also does not work for internal methods with `SecuritySafeCriticalAttribute` attribute. – Vyacheslav Volkov Aug 21 '14 at 14:11

Access to private method using reflection in C#/Silverlight applications

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