Question

I have an entity class that represents a person and an enum that represents permissions that a person has. I am trying to map this relationship to a database using nhibernate mapping by code without any success.

The code looks like this:

public enum Permissions
{
  None = 1,
  CanUpdate = 2,
  CanInsert = 3,
  CanDelete = 4
}

public class Person
{
   private ICollection<Permissions> permissions;

   public Person()
   {
      this.permissions = new Collection<Permissions>();
   }

   public virtual ICollection<Permissions> Permissions
   {
      get
      {
         return this.permissions;
      }
   }
}

public class PersonMap : ClassMapping<Person>
{
   public PersonMap()
   {
      this.Set(
        x => x.Permissions,
        m =>
          {
             m.Access(Accessor.Field);
             m.Key(k => k.Column("PersonId"));
             m.Table("PersonHasPermission");
          },
        map => map.Element(
        p =>
          {
             p.Column("PermissionId");
             p.Type<NHibernate.Type.EnumType<Permissions>>();
          }));
    }
}

The database tables look like this:

Person
-----------------------
PersonId (PK, uniqueidentifier, not null)
Name (nvarchar(max), not null)


PersonHasPermission
-----------------------
PersonId (PK, FK, uniqueidentifier, not null)
PermissionId (PK, FK, int, not null)

So, with this configuration I do not get any exceptions but whenever I try to fetch the permissions for a person the collection is always empty even though there is data in the database.

I’m hoping that the code above is explains what I am trying to achieve, but do let know if further clarity is required.

Any help with this would be much appreciated. Thanks in advance.

Answer 1

I am using XML configuration, where I can map even protected or private members. So, surprising for me is that you are not receiving any Exception. Because your Collection does not have any setter (public nor protected). I would expect something like this:
NHibernate.PropertyNotFoundException: {“Could not find a setter for property ‘Permissions’ in class ‘Person'”}
But maybe fluent is able to translate your mapping from Property to field.

I tried to test your code with a public setter or field (both shown below) and it worked. there is my snippet of xml mapping:

<!-- public or protected setter -->
<bag name="Permissions" inverse="false" lazy="true" table="PresonHasPermission" cascade="all">
   <key column="PersonId" />          
   <element type="Permissions" column="PermissionId" />
</bag>

<!-- accessing the field -->
<bag name="permissions" inverse="false" lazy="true" table="PresonHasPermission" cascade="all"
   access="field" >
   <key column="PersonId" />          
   <element type="Permissions" column="PermissionId" />
</bag>

(Leaving your class definition unchanged when mapping to field)