Fluent NHibernate and XML columns

Question

I'm building a new site from scratch and am considering using Fluent NHibernate for my ORM. I think it'll handle everything easily except, possibly, my XML columns. I've never built a site with NHibernate at all (though I've used Hibernate for Java) so consider me a n00b.

Ideally I'd like the XML to be treated as an XElement as Linq-to-SQL does.

Can I do this with (fluent) NHibernate? What if I want to use auto mapping?

Answer 1

You can use the IUserType defined here: https://nhibernate.jira.com/secure/attachment/12905/XmlType.cs

It uses XmlDocument, but you can easily modify it to work with XElement instead.

Update: This has been included in NHibernate 3. Both XmlDocument and XDocument are available.

Answer 2

Since I struggled to find a solution, I'd like to share my solution here (with XDocument instead of XElement, but at least valid for XML columns).

First create this convention;

using System.Xml.Linq;
using FluentNHibernate.Conventions;
using FluentNHibernate.Conventions.AcceptanceCriteria;
using FluentNHibernate.Conventions.Inspections;
using FluentNHibernate.Conventions.Instances;

public class XmlTypeConvention : IUserTypeConvention
{
    public void Accept(IAcceptanceCriteria<IPropertyInspector> criteria)
    {
        criteria.Expect(x => x.Type == typeof(XDocument));
    }

    public void Apply(IPropertyInstance instance)
    {
        instance.CustomType<NHibernate.Type.XDocType>();
    }
} 

Then remember to add the convention;

Conventions.Add<XmlTypeConvention>();

Now, if your domain entity has a XDocument property it will turn into an XML column in the database.