using Nhibernate lazy proxys with a webservice - nhibernate

Question

Recently i had some performance problems in a SOAP webservice I wrote a while ago. I noticed I had a lot of queries going on and my hbm.xml mappings where full of lazy=false statements. I upgraded to NHibernate 3.0 and removed the lazy = false stuff and everything was a LOT faster....but now i am getting the following error:
System.InvalidOperationException: There was an error generating the XML document. ---> System.InvalidOperationException: The type UserProxy was not expected. Use the XmlInclude or SoapInclude attribute to specify types that are not known statically.
User is a class of which i removed the lazy=false property from the class tag like this:
<class name="User" table="Users" >
<id name="DatabaseID" unsaved-value="0" column="ID" type="integer" >
<generator class="native"/>
</id>
<property name="IsExpert"/>
.....more stuff here....
</class>
My webservice has a method like this (simplified a little..in real-life i use a repository-like pattern between the service and nhibernate):
[WebMethod]
public User GetUser(int userid)
{
session = GetCurrentSession();
return session.Load<User>(userid);
}
The webservice expects to serialize a user and NHibernate gives me a UserProxy (which is not a user exactly). How should I overcome this?

Answer 1

Don't return entities from the web method. Use a DTO.

Answer 2

Webservices cannot serialise proxies - session.Load(userId) will return a proxy. You should user session.Get(userId) .
I think the answers saying you should use DTOs are not helpful, there is a time and place for DTOs and sometimes you may just want to return the entity.
If the User has child proxy properties, I have a class for handling this situation. Basically it loops through all properties (using reflection, and recursively going through child objects and collections) and uses the NHibernate.IsInitialized to check whether the property is a proxy or the genuine article. If it is a proxy then it sets it to null, thus making it possible for WCF to serialise it.