Invoke method using Reflection on COM Object

Question

I have an instance of a COM object... which is created like this:

Type type = TypeDelegator.GetTypeFromProgID("Broker.Application");
Object application = Activator.CreateInstance(type);

When I try to invoke a method:

type.GetMethod("RefreshAll").Invoke(application, null);

-> type.GetMethod("RefreshAll") returns null. When I try to get all the methods with type.GetMethods(), there is only these methods:

GetLifetimeService
InitializeLifetimeService
CreateObjRef
ToString
Equals
GetHashCode
GetType

Where is the RefreshAll Method? And how can I invoke it?

Nathan W · Accepted Answer · 2010-07-08 00:35:27Z

13

You can't use GetMethod on COM objects, you have to use a different way:

this.application.GetType().InvokeMember("RefreshAll", BindingFlags.InvokeMethod, null, this.application, null);

I am using this way in a old project that uses COM so it should work ok for you.

answered Jul 8, 2010 at 0:35

Nathan W

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3 Comments

user585968 Over a year ago

Though a fine answer at the time, c# 4 makes it much easier to perform COM-interop via the dynamic keyword below

Waescher Over a year ago

Attention, coming from using dynamic in my tool github.com/awaescher/RepoZ I discovered heavy memory leaks with it. I switched to the answer from Nathan W to fix that! See more here: stackoverflow.com/questions/33080252/…

Waescher Over a year ago

See the other comments on MickyD's answer on how to deal with the issue ...

user585968 · Accepted Answer · 2015-02-07 00:11:41Z

5

I realise this is a late answer but c# 4 changes things a bit with the introduction of the dynamic keyword which was designed with COM-interop in mind.

MSDN:

The COM interop scenario that the C# team specifically targeted in the C# 4 release was programming against Microsoft Office applications, such as Word and Excel. The intent was to make this task as easy and natural in C# as it always was in Visual Basic. [1]

Your code now becomes:

Type type = TypeDelegator.GetTypeFromProgID("Broker.Application");
dynamic application = Activator.CreateInstance(type);
application.RefreshAll(); // <---- new in c# 4

Now you won't see RefreshAll() in Visual Studio statement completion so don't be alarmed. It will compile.

[1] Understanding the Dynamic Keyword in C# 4

answered Feb 7, 2015 at 0:11

user585968

9 Comments

Waescher Over a year ago

Attention, coming from using dynamic in my tool github.com/awaescher/RepoZ I discovered heavy memory leaks with it. I switched to the answer from Nathan W to fix that! See more here: stackoverflow.com/questions/33080252/…

user585968 Over a year ago

@Waescher odd considering MS made it for COM in the first place. I suspect you are just not releasing things properly which has nothing to do with dynamic

user585968 Over a year ago

@Waescher ooh I just did some googling and it appears you are correct. Nasty little dynamic. Good find

Waescher Over a year ago

Thanks for the correction. That link I posted (stackoverflow.com/questions/33080252/…) shows exactly the problem I face as well, with all the RuntimeBinder stuff. And don't get that wrong, that leak is huge: i.imgur.com/5ucIcI6.png. I might add that I call that method containing the dynamic quite often but anyways ...

user585968 Over a year ago

@Waescher No, thank-you. I guess I wasn't noticing it in my stuff as the apps don't run for very long then exit. Hopefully MS will rectify. :)

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