Question

Given:

• I’m trying to create a REST API using ASP.NET MVC.
• I’m using NHibernate in my data access layer.

Problem:

• I’m can’t XmlSerialize ISet properties.

I get errors like the following:

Cannot serialize member
[namespace].[entity].[property] of
type
Iesi.Collections.Generic.ISet`1[[namespace].[entity],
[assembly], Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null]]
because it is an interface.

• I’ll freely admit: I’m very new to NHibernate.
  • So I don’t know what my options are.
• I believe that I need to use a set as opposed to a bag because my collections contain unique items.
• When I converted the ISet properties to HashedTable properties (i.e. a concrete class), I got errors like the following:

You must implement a default accessor
on
Iesi.Collections.Generic.HashedSet`1[[namespace].[entity],
[assembly],
Version=1.0.0.0, Culture=neutral,
PublicKeyToken=null]] because it
inherits from ICollection.

My questions:

• What should I do to remedy this situation?
  • Should I implement default accessors in all of my entity classes?
    • If so, is there a recommended pattern for doing so?

As a sidenote, I tried Googling for help.
– I don’t think this is a new problem.

Answer 1

NHibernate serialization has been treated a lot on stackoverflow. See:

• C# Castle ActiveRecord: How to elegantly (XML) serialize ActiveRecord objects?
• How do I serialize all properties of an NHibernate-mapped object?
• NHibernate and WCF Serialization(Unidirectional)
• JSON.NET and nHibernate Lazy Loading of Collections
• Which .NET JSON serializers can deal with NHibernate proxy objects?
• DTOs vs Serializing Persisted Entities
• Returning NHibernate mapping classes from WCF services

Bottom line: use DTOs.