Type.InvokeMember when method has a Dictionary parameter

Question

I am getting a

Method 'MyNameSpace.MyClass.MyMethod' not found.

when I changed a parameter of MyMethod from Hashtable to Dictionary<string, string>.

The invoke call is

return = t.InvokeMember("MyMethod", (BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.InvokeMethod), null, instance, params);

When I do

Type type = a.GetType(String.Concat(DLLName, ".MyClass"));
var methods = t.GetMethods();

methods contains MyMethod() so it is there.

Can anyone shed any light?

The params are

Object[] params = new Object[11];
...
params[5] = foo.myHashtable.Cast<DictionaryEntry>().ToDictionary(d => d.Key, d => d.Value);   
...

The MyMethod signature is

public MyMethodReturn MyMethod(Byte[] m, Hashtable d, Mutex mut, FileStream logFile, Hashtable t, Dictionary<string, Byte[]> fields, bool e, byte[] k, int hashCode, bool h, Byte[] mm)

`foo.myHashtable.Cast().ToDictionary(d => d.Key, d => d.Value);` doesn't actually put the dictionary anywhere - it just drops it on the floor for the garbage collector to deal with; did you assign this to a variable or anything? Better: can you show the *actual* code that *actually* calls `InvokeMember` with your inputs? And preferably the *actual* signature of `MyMethod` (because I have concerns about what may be lurking in the `...`) — Marc Gravell, Jul 01 '13 at 09:47

score 1 · Accepted Answer · answered Jul 01 '13 at 09:51

You have:

params[5] = foo.myHashtable.Cast<DictionaryEntry>()
               .ToDictionary(d => d.Key, d => d.Value);

This creates a Dictionary<object,object>, which does not match the signature. This is because a DictionaryEntry has object Key {get;} and object Value {get;}, and the compiler is using those to infer the types for the dictionary (generic type inference).

Try:

params[5] = foo.myHashtable.Cast<DictionaryEntry>()
               .ToDictionary(d => (string)d.Key, d => (byte[])d.Value);

This will create a Dictionary<string,byte[]>, which should match.

score 0 · Answer 2 · edited Jan 14 '16 at 03:18

0

Reflection can not find the method because the method expects a hash table not a dictinary, dictionary doesn't inherit from hashtable so you can not use dictionary instead of hashtable. Method signiture should match before reflection can invoke a method.

edited Jan 14 '16 at 03:18

Josh Crozier

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answered Jul 01 '13 at 09:49

Alexandr Mihalciuc

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from the question: "The MyMethod signature is `public MyMethodReturn MyMethod(... Dictionary fields ...)`" - looks like a dictionary to me... – Marc Gravell Jul 01 '13 at 09:49
Yep, Sorry didn't notice it – Alexandr Mihalciuc Jul 01 '13 at 09:51

Type.InvokeMember when method has a Dictionary parameter

2 Answers2