Why does WCF return myObject[] instead of List<T> like I was expecting?

Question

I am returning a List from my WCF method. In my client code, it's return type shows as MyObject[]. I have to either use MyObject[], or IList, or IEnumerable...

WCFClient myClient = new WCFClient();

    MyObject[] list = myClient.GetMyStuff();
or
    IList<MyObject> list = myClient.GetMyStuff();
or
    IEnumerable<MyObject> list = myClient.GetMyStuff();

All I am doing is taking this collection and binding it to a grid. What is the best object to assign my returned collection?

Answer 1

When you add the service reference to the client project click the advanced button and change collection type from array to what you want it to be...

Answer 2

When you use svcutil.exe to create you client code you need to tell it how to resolve certain references that are not available to it.

This is how you would do it for List<T>:

svcutil /o:YourService.cs /ct:System.Collections.Generic.List`1 http://example.com/mex

Answer 3

You can specify that you want to use a generic list instead of an array by clicking the advanced button when you add a reference, or you can right click on the service reference and choose configure to change it in place.

The reason is that WCF serializes Generic lists as arrays to send across the wire. The configuration is just telling svcutil to create a proxy that converts them back to a generic list for your convenience.

Answer 4

Stever B is correct. WCF tries really hard not to be coupled to .NET. You may want to allow a Java client to connect to your component. Arrays are interoperable. Generic .NET lists aren't.

However, you're more than welcome to create your own proxy class that will convert the array back into a List or anything else that you'd like. The nice thing about manually creating your own proxies is that you're in complete control of what they do.

Answer 5

@SteveB, All, Does this mean that if my WCF service returns an IEnumerable that it will be serialized to an array, as well?

Also - I assume this behavior works for function parameters? That is given the following I can pass an array from say, Java?

public bool SomeFunc(IEnumerable<int> ints) { return true; }

Answer 6

Here is a post which describes the solution for automatic and manual generation of proxy to resolve the problem http://sivakrishnakuchi.blogspot.com/2010/05/solution-array-for-list-in-wcf.html