Rails - Sep 2005 - habtm, fixtures, typical troubles with associations..

Hi,

I have a Project model, and a Party model (as in people, not
celebrations ;). Parties can have one or more Roles, like so:

class Party < ActiveRecord::Base
  has_and_belongs_to_many :roles
end

I have the appropriate join table (parties_roles) to facilitate this,
as well as a call to habtm in the Role model.

The Project model references (using belongs_to) four parties, all
having different roles, like so:

class Project < ActiveRecord::Base
  belongs_to :primary_contact, :class_name => "Party"
  belongs_to :liaison, :class_name => "Party"
  belongs_to :data_source, :class_name => "Party"
  belongs_to :applicant, :class_name => "Party"
end

I have a project fixture like the following (fields omitted for brevity):

first_project:
  id: 1
  name: 01-234
  data_source: 4

And a party fixture: 

data_source:
  id: 4
  first_name: James
  last_name: Hughes

In project_test.rb:

  def test_associations

    assert_equal @project.name, ''01-234''
    assert_equal @project.data_source.last_name, ''Hughes''
  end

The first assertion passes; the second fails with, "NoMethodError:
undefined method `last_name'' for nil:NilClass. "

What am I missing?

Thanks!

ps. I''m loading fixtures in the project test file as follows:

  fixtures :projects, :parties, :parties_roles, :roles

-- 
James Hughes
Web application developer
Centre for Health Services and Policy Research
Vancouver, BC

On 9/20/05, James Hughes
<hughes.james-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Hi,
>
> I have a Project model, and a Party model (as in people, not
> celebrations ;). Parties can have one or more Roles, like so:
>
> class Party < ActiveRecord::Base
>   has_and_belongs_to_many :roles
> end
>
> I have the appropriate join table (parties_roles) to facilitate this,
> as well as a call to habtm in the Role model.
>
> The Project model references (using belongs_to) four parties, all
> having different roles, like so:
>
> class Project < ActiveRecord::Base
>   belongs_to :primary_contact, :class_name => "Party"
>   belongs_to :liaison, :class_name => "Party"
>   belongs_to :data_source, :class_name => "Party"
>   belongs_to :applicant, :class_name => "Party"
> end
Well, I guess I might as well post my solution, for future generations.
Adding the :foreign_key option did the trick:
belongs_to :primary_contact, :class_name => "Party", :foreign_key
=>
"primary_contact"

Not sure why I thought I could get away without that...
J

--
James Hughes
Web application developer
Centre for Health Services and Policy Research
Vancouver, BC