Debugging a REST WCF Service

Question

I am new to the REST model with WCF. I downloaded the WCF Rest Service Template for .NET 4.0.

I have a project that is using the EF to retrieve a POCO entity from a database and then return that entity to the user.

The [WebGet] method executes properly and I can debug it to see the data being returned. However, it seems, when serializing the POCO object and trying to return it to the caller, the system is failing.

A few points here:

1. I can create a manual POCO object and return it fine. However, when it is returning a POCO object sourced from the database (using EF), the call fails upon return (the EF query work properly--the WebGet method just doesnt return it back to the caller.
2. The HTTP response code is 400 Bad Request. I don't get any other info (and no .NET exception).
3. The same behavior occurs when running in IIS or the Visual Studio web server.

How should I go about debugging this issue?

Thanks!

Answer 1

On 12/22/2010 6:25 PM, pmaroun wrote:

> I am new to the REST model with WCF. I downloaded the WCF Rest Service

> Template for .NET 4.0.

>

> I have a project that is using the EF to retrieve a POCO entity from a

> database and then return that entity to the user.

>

> The [WebGet] method executes properly and I can debug it to see the data

> being returned. However, it seems, when serializing the POCO object and

> trying to return it to the caller, the system is failing.

>

> A few points here:

>

> 1. I can create a manual POCO object and return it fine. However,

> when it is returning a POCO object sourced from the database

> (using EF), the call fails upon return (the EF query work

> properly--the WebGet method just doesnt return it back to the caller.

> 2. The HTTP response code is 400 Bad Request. I don't get any other

> info (and no .NET exception).

> 3. The same behavior occurs when running in IIS or the Visual Studio

> web server.

>

> How should I go about debugging this issue?

 

Go look at the IIS error logs, use Google or Bing and look up how to do it..

 

 

Answer 2

The IIS logs focus on the HTTP request / response codes.  In the above case, the code was returning 400 without any further information.  I was able to see the request and response details clearly.  However, a problem was occuring before IIS was sending the response and .NET was not throwing an error.

After some further investigation, I found this to be a serialization issue.. The object that was trying to be serialized was not the POCO object, it was a System.Data.Entity.DynamicProxies class generated by EF.