has_and_belongs_to_many question

rubyonrails-talk
1

Looks like you've defined user_id as either PRIMARY KEY or UNIQUE in the database, which you shouldn't do. The book shows you how to use a migration to create the join table.

2

I had this problem a while ago. IIRC, Rails does not automatically create a primary key column on HABTM join tables the way it does for a Users table by creating a user_id column. You can verify this by executing a ‘SHOW COLUMNS FROM requests_users;’ in mysql and checking that there is no requests_users_id column.

The solution is to do what the previous poster suggested and create a migration for the join table. In the migration, you should specify the primary key column and also add indexes on request_id and user_id (as appropriate):

class CreateRequestsUsers < ActiveRecord::Migration def self.up create_table :requests_users do |t| t.column :request_id, :integer, :allow_null => false t.column :user_id, :integer, :allow_null => false

  t.column :request_user_id, :integer, :allow_null => false
  t.primary_key :request_user_id
end
add_index :requests_users, :request_id
add_index :requests_users, :user_id

end

def self.down remove_index :requests_users, :request_id remove_index :requests_users, :user_id drop_table :requests_users end end

-Dan