rails has_many and has_many :through error

Question

I have this code in family_service model:

has_many :families_users
has_many :users, :through => :families_users

But when trying to execute in a loop (service is a family_service)

users << service.users

I get this error

ActiveRecord::HasManyThroughOrderError in Budgets#index

Cannot have a has_many :through association 'FamilyService#users'
which goes through 'FamilyService#families_users' before the through association is defined.

But as you can see, it is defined as it should be.

Answer 1

After a big effort, I found that I have this line before the lines in the question:

has_and_belongs_to_many :users, :join_table => :families_users

So this line actually uses a: join_table which is equal to :through before the actual line of has_many:families_users .

That's why I got the error.

Hopefully someone that is upgrading to rails 5 will find this handy.