Func is a serializable class, but yet when I try to pass it as a parameter through a service. I'm told it "isn't a known type". I've tried the solutions here to no avail.
Many thanks out there...
+3
A:
No, basically. You can't pass an Expression either, since it talks to MemberInfo nodes. Your best bet is a string representation of the predicate.
Marc Gravell
2009-02-19 21:48:13
+4
A:
There's work happening to enable it. Check out the Expression Tree Serialization project on the MSDN Code Gallery.
Matt Hamilton
2009-02-19 21:51:08
That's really scary. Expressions are great for application code, but there are some serious security implications for service code.
Michael Meadows
2009-02-19 21:54:21
Yeah, but I can imagine a sort of "Linq to the Cloud" project where you pass a "where" clause to a service, and it returns, say, the first 100 rows matching that clause.
Matt Hamilton
2009-02-19 21:55:42
For that scenario, perhaps the type of wrapping that Astoria does is the way to go...
Marc Gravell
2009-02-20 00:36:48
Sure. I guess it depends on what you're trying to do. As I understand Astoria, it's very "single-table" focused - it'd be hard to pass an expression that looked at Order.Customer.Address.State == "CA", for example.
Matt Hamilton
2009-02-20 00:54:17
I am trying to do exactly the "where" scenario that you mentioned.
KevDog
2009-02-20 01:25:21
+3
A:
Wow, what a wild question - you're essentially asking, how do I serialise functions? Which seems quite strange from an OO perspective, but is a perfectly natural question from a functional perspective.
Interesting ...
Travis
2009-02-20 03:47:34
A:
Can you return any other delegate type in WCF? I don't think so. What would it even mean?
John Saunders
2009-02-20 13:11:01
A:
Hi,
Could you please explain a scenario where it would be useful to expose Func in the service boundary? Sniff, Sniff... it has a certain smell to it that I wouldn't characterize as proper service-orientation.
--larsw
larsw
2009-02-20 13:33:35
I want to pass a func as a parameter in a service call for querying against the repository.
KevDog
2009-02-20 13:38:14
I can see the use of it - but I still would not consider it a "kosher" thing to do - it would certainly be a bad option if you want your service to be interoperable.
larsw
2009-02-20 13:52:50
Why? You make an assertion (not necessarily a bad thing) and don't give an explanation. And I think you are only allowed to say your own ideas smell, doesn't seem too nice without knowing the context of the problem. Regardless, I'm not the one who down-modded you on it.
KevDog
2009-02-20 16:10:33
As for why sending a Func<blah, foo> will adversely affect interoperability, a Func is a .NET-specific Type. There is no generic mapping to XML, and then to PHP, Java, C, or anything else.
Cheeso
2009-02-24 07:28:06