ruby - Rails 4 HABTM has_many :through -

team, looking specific (newbie) situation on rails 4 association. have 3 models:

class brand < activerecord::base  has_many :lines, dependent: :destroy  has_many :products, through: :lines, dependent: :destroy end  class line < activerecord::base  belongs_to :brand  has_and_belongs_to_many :products end  class product < activerecord::base  has_and_belongs_to_many :lines  has_many :brands, through: :lines end 

this configuration works when trying check products under specific brand (or line) , viceversa: different brands (or lines) available specific product. however, when comes delete/destroy there issue. getting rspec error:

activerecord::hasmanythroughcantassociatethroughhasoneormanyreflection: cannot modify association 'brand#products' because source reflection  class 'product' associated 'line' via :has_and_belongs_to_many. 

we have made research on exception, checked rails api, no luck, examples found showing different model configuration. what's missing on approach?

appreciate guys!

in opinion, should this:

class brand < activerecord::base  has_many :lines, dependent: :destroy  has_many :products, through: :lines, dependent: :destroy end  class line < activerecord::base  belongs_to :brand  has_and_belongs_to_many :products end  class product < activerecord::base  belongs_to :brand, through: :line  has_and_belongs_to_many :lines end 

and in migrations:

create_table :brands , force: true |t|   t.string :name   ...   t.timestamps null: false     end  create_table :lines , force: true |t|   t.string :name   t.belongs_to :brand   ...   t.timestamps null: false     end  create_table :products , force: true |t|   t.string :name   ...   t.timestamps null: false     end  create_table :line_products, force: true, id: false |t|   t.belongs_to :line, index: true   t.belongs_to :product, index: true end 

i hope help.