Nhibernate and linq problem

Question

I get the following expression:

_senderRepos.Get(s => s.User.Email == fromAddress);

which results in

could not resolve property: User.Email of: Module.Fax2Pdf.MailToFax.Models.Sender

class:

public class Sender
{
    public virtual int Id { get; set; }
    public virtual Site Site { get; set; }
    public virtual User User { get; set; }
}

mapping:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" auto-import="true">
  <class name="Module.Fax2Pdf.MailToFax.Models.Sender, Module.Fax2Pdf" table="fax_allowed_senders">
    <id name="Id" column="id">
      <generator class="sequence">
        <param name="sequence">fax_allowed_senders_id_seq</param>
      </generator>
    </id>
    <many-to-one column="site_id" name="Site" />
    <many-to-one column="user_id" name="User" />
  </class>
</hibernate-mapping>

And the User class DO have a Email property in it's mapping file. What am I doing wrong?

Update, user mapping

    <?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" auto-import="false">
  <class name="Gate.Users.User, Gate.Models" table="users">
    <id name="Id" column="id">
      <generator class="sequence">
        <param name="sequence">users_id_seq</param>
      </generator>
    </id>
    <many-to-one column="site_id" name="Site" />
    <property name="FirstName" column="first_name" type="String" length="30"/>
    <property name="LastName" column="last_name" type="String" length="30"/>
    <property name="CanDelete" column="can_delete" type="boolean" />
    <property name="Email" column="email" type="String" length="255"/>
    <property name="Department" column="department" type="String" length="30"/>
    <property name="Title" column="title" type="String" length="30"/>
    <many-to-one class="Gate.Extensions.Extension, Gate.Models" column="extension_id" name="Extension" />
    <property name="Status" column="status" type="integer" />
    <property name="CreatedAt" column="created_at" />
    <property name="UpdatedAt" column="updated_at" />
    <property name="TimeZone" column="timezone" type="integer" />
    <property name="MiddleNames" column="middle_names" type="string" />
    <property name="NamePrefix" column="name_prefix" type="string" />
    <property name="NameSuffix" column="name_suffix" type="string" />
    <property name="DateOfBirth" column="dob" />
    <property name="RemovedAt" column="removed_at" />
    <property name="ProxyMedia" column="proxy_media" type="boolean" />
  </class>
</hibernate-mapping>

Answer 1

Apologies. I was using QueryOver on the Get method in the Repository and Query for everything else. It works when I switched to Query.

Answer 2

What if you called .Expand() on your IQueryable first?

So, assuming you had a session, it might look like this:

var senders = 
    (from sender in session.Query<Sender>().Expand("User")
     where sender.User.Email == fromAddress
     select sender);

Unfortunately that requires you to import an NHibernate extension method.