n:through:1 Relation or n:m with another table

# Hello,

# currently I have 3 tables: users, projects and customers but customers
# soon should become part of users too so I decided to create a relation
# through projects but has_many :through doesn't work in this case,
# because AR generated me a wrong WHERE clause.

## create_projects.rb
create_table "projects", :force => true do |t|
   t.column "title", :string, :null => false
   t.column "description", :text
   t.column "fee", :integer, :default => 2000, :null => false
   t.column "tax", :integer, :default => 19, :null => false
   t.column "client_id", :integer, :null => false
   t.column "agent_id", :integer, :null => false
end

class User < ActiveRecord::Base
   has_many :clients, :through => :projects
   #...
end

class Project < ActiveRecord::Base
   belongs_to :client, :class_name => 'Customer', :foreign_key => :client_id
   belongs_to :agent, :class_name => 'User', :foreign_key => :agent_id
   #...
end

# The definition of an class_name or the relation from User class itself
# seems to baffle AR to build a wrong WHERE clause, although I defined a
# foreign_key in projects relation...
# So I tried to use a n:m relation, which seems to fit better, but I always
# get duplicates which I could not get rid off using :uniq => true.

## user.rb
class User < ActiveRecord::Base
   has_and_belongs_to_many :clients,
     :class_name => 'Customer', # Becomes a User in future
     :association_foreign_key => :client_id,
     :foreign_key => :agent_id,
     :join_table => :projects,
     :uniq => true # !! Doesn't seem to work :frowning:
   #...
end

clients = user.clients.uniq # !! Doesn't work too :frowning:

Sincerely
Florian