Why doesn't @event.users.size work?

Question

Trying to get to total number of users for a given event and I'm thinking what I've got should work, but I get the following:

Could not find the source association(s) :squads_users in model Squad. Try 'has_many :users, :through => :squads, :source => '. Is it one of :team, :event, :event_division, :users, :point_adjustments, :checkpoint_squads, :division, or :checkpoints?

My ActiveRecord Kung Fu is weak :-/

Event

has_many :squads
has_many :users, :through => :squads

Team

 has_many :squads

Squad

 belongs_to :event
 belongs_to :team
 has_and_belongs_to_many :users

SquadsUsers

 belongs_to :user
 belongs_to :squad

User

 has_and_belongs_to_many :squads

Answer 1

You should remove your SquadsUsers model and just have a table called squads_users. has_and_belongs_to_many will automatically use this table without needing the additional model.

Answer 2

Is your join model really named SquadsUsers? That might be the problem. It should be SquadUser.

Also, I think you want a many-to-many relationship between Event and Team, not Event and Squad, correct? In which case you need this:

Event
has_many :event_teams
has_many :teams, :through => :event_teams

EventTeam
belongs_to :event
belongs_to :team

Team
has_many :squads

Squad
belongs_to :team
has_many :squad_users
has_many :users, :through => :squad_users

SquadUser
belongs_to :squad
belongs_to :user

User
has_many :squads