Trouble with IDictionary and <set>

kellygreer1 · **Posted:** Thu Sep 20, 2007 7:19 pm

When trying to do a many-to-many relationship I am having trouble with the .NET code.

If I use the non-Generic IDictionary

Code:

        public virtual IDictionary Skills
        {
            get { return _skills; }
            set { _skills = value; }
        }

I then get the error:
System.InvalidCastException: Unable to cast object of type 'NHibernate.Collection.PersistentSet' to type 'System.Collections.IDictionary'.

If I use the Generic version:

Code:

        public virtual IDictionary<int, Skill> Skills
        {
            get { return _skills; }
            set { _skills = value; }
        }

I get the error:
NHibernate.MappingException: Error mapping generic collection Doa.Domain.Entities.Profile.Skills: expected 1 generic parameters, but the property type has 2

Huh????

How do I pass one parameter to the Generic IDictionary?
More information below.

Thanks,
kellygreer1

Hibernate version:
2.2

Mapping documents:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
namespace="Doa.Domain.Entities" assembly="Doa.Domain">
<class name="Profile" table="Profiles">
<id name="Id" column="id" type="Int32" unsaved-value="-1"
access="field.camelcase-underscore">
<generator class="native" />
</id>
<property name="UserName" column="ntlogon" type="string" length="24" access="field.camelcase-underscore">
</property>
<property name="LastName" column="last_name" type="string" length="18" access="field.camelcase-underscore">
</property>
<property name="FirstName" column="first_name" type="string" length="18" access="field.camelcase-underscore">
</property>
<property name="MiddleName" column="middle_name" type="string" length="18" access="field.camelcase-underscore">
</property>

<set name="Skills" table="ProfileSkills">
<key column="profile_id" />
<many-to-many column="skill_id" class="Skill" />
</set>
</class>
</hibernate-mapping>

karlchu · **Posted:** Fri Sep 21, 2007 12:02 am

You must map a <set> to an Iesi.Collections.ISet or Iesi.Collections.Generics.ISet<T>.

kellygreer1 · **Posted:** Fri Sep 21, 2007 1:01 am

So does that mean this guy's examples are wrong?
http://www.theserverside.net/tt/article ... NHibernate

he seems to map <set> to IDictionary

oh well - will try what you said

thanks Karl,

kellygreer1

karlchu · **Posted:** Fri Sep 21, 2007 10:39 am

I am afraid that the example is indeed wrong, or misleading at least. I am quite certain, as far as my own experience goes, one cannot map a <set> to an IDictionary. That is why the NHibernate needs to depend on the Iesi collection library in the first place.