Rails convention assumes that for column names on join tables that hold foreign keys that point to the other model, the association name with the suffix_id added to the model name will be used. You can specify the name of the foreign key directly with the: foreign_key option.
By convention, Rails assumes that the column used to hold the foreign key on this model is the name of the association with the suffix _id added. The :foreign_key option lets you set the name of the foreign key directly:
--Translation for yourself
Rails convention assumes that the column name that holds the foreign key in this model is the association name with the suffix _id. You can use the: foreign_key option to specify the column name that holds the foreign key.
Foreign_key that Rails customarily assumes
class Book < ApplicationRecord
belongs_to :author(, foreign_key: author_id)
end
Rails expects a foreign_key with __id in the association name, so the: foreign_key option is needed in the example below.
class Book < ApplicationRecord
belongs_to :author, class_name: "Patron",
foreign_key: "patron_id"
end