NHibernate: Mapping query results to a list property in mapping file

I have a Contact class and I want to provide the users with AutoComplete for City and Province.

I Thought I create two collections in the Contact object and load the Cities and Provinces from the contact table on them:

public class Contact {  
    public virtual string Name { get; set; }  
    public virtual string City { get; set; }  
    public virtual string Province { get; set; }  
    public virtual IList<String> Cities { get; set; }  
    public virtual IList<String> Provinces { get; set; }  
}

And have the mapping file like this:

<class name="Contact">  
    <id name="Id">  
        <generator class="native">  
            <param name="sequence">contact_id_seq</param>  
        </generator>  
    </id>  
<property name="Name" />  
<property name="City" />  
<property name="Province" />  
<property name="Cities" type="string" formula="SELECT DISTINCT city FROM contact" />  
<property name="Provinces" type="string" formula="SELECT DISTINCT province FROM contact" />  
</class>

But this does not work. Is there any way this can be accomplished?

Thank开发者_Python百科 you.

formula on property is an SQL expression that defines the value for the property, so the select should return a single value. In addition by working in the way you proposed you will duplicate those values on each entity, maybe is better to define it as a static list and fill the value by a custom hql when, for example, a new session is created.