How should I handle differences with "Specified" fields in WCF services using VS 2010 vs VS 2008?

We're attempting to move to VS 2010 and开发者_开发百科 we've noticed some odd behavior with our WCF services.

In VS 2008, when I add a given WCF service reference, for each object field that's not a reference type, the Object browser shows a fieldNameSpecified bool property. I realize that this exists so that there's a way to determine whether or not the value coming back from the service actually has a value, since DateTime, ints, etc can't be null.

When I try to add the same reference in VS 2010 (set to .Net 3.5), all of these fieldNameSpecified fields are missing. We have code that we wrote in VS 2008 that look at these fieldNameSpecified fields which causes our apps to be broken when attempting to use VS 2010 (because the proxies generated in VS 2010 don't have these fieldNameSpecified fields).

Is there a way to get VS 2010 to put these specified fields back in? Is there some other solution that won't require us to rewrite our code?

Also, what is the proper VS 2010 way of determining whether or not a value type field (int or DateTime) actually has valid data in it coming back from the service?

Any help GREATLY appreciated!

Clarification: The fieldNameSpecified fields are NOT part of the WSDL. VS 2008 apparently adds these into the proxy for you as a convenience...

I ran into an opposite situation recently. There wasn't any xxxspecified field before, but now they showed up. And we have only used VS2008. This acutally cause the value of the optional fields not being passed to the client application, since the xxxspecified fields are default to false.

If you look at both versions of the auto generated reference.cs file under your service reference, you should notice the difference. One uses DataContractSerializer, the other uses XMLSerializer.

When you add the service reference, if you use the URL for the service, e.g. http://localhost/MyService.svc, it would use DataContractSerializer. If you use the URL for the WSDL, e.g. http://localhost/MyService.svc?wsdl, it would use XMLSerializer.

You can use an attribute called EmitDefaultValue to resolve your problem as well. Follow these instructions:

http://bukovics.wordpress.com/2007/03/23/exposing-nullable-fields-to-net-11-web-service-clients/

This also explains why you get a fieldNameSpecified property. It's exactly what you need to fix your problem.

As I understand it, if the data contract requires the properties (for example, if you're using a [DataMember(IsRequired=true)] attribute), the "Specified" fields aren't auto-generated. Unfortunately, making the fields non-required would require a code change, but at least it wouldn't do so on the client.

An alternate way to allow callers to be able to not specify parameters (don't know if it's more VS 2010-ish than the "Specified" fields) is to use Nullable<> types.

I haven't tested it, but perhaps you could remove your Service References and instead put a pre-build step into your projects to run the old version of WSDL.exe to generate the proxies.