Rails关联使用'model'。'model_id'而不是'model'。'id'触发SQL where子句

Question

In my Card model, I have the following associations :

has_many :sub_cards, ->(obj) { where('parent_card_id = ?', obj.id) },
           inverse_of: :parent_card, :class_name => 'Card'
belongs_to :parent_card, class_name: 'Card', optional: true

Whenever I try to use them, for example in the console typing c.sub_cards , I get the following error :

ActiveRecord::StatementInvalid: Mysql2::Error: Unknown column 'cards.card_id' in 'where clause': SELECT cards .* FROM cards WHERE cards . card_id = 237 AND (parent_card_id = 237)

In fact, the SQL request has 'cards'.'card_id' = something , whereas it should be 'cards'.'id' = something if I refer to my other working associations. The problem is I can't find where this syntax comes from.

Has somebody ever experienced this issue ?

Thank you in advance for your help.

Answer 1

You can specify which attribute is the foreign key of the relation by passing :foreign_key => "some_attribute_id" . Hope this helps. Good luck!

EDIT:

Don't know if this works for you, but I would write it kinda like this:

has_many :sub_cards, ->(obj) { where('parent_card_id = ?', obj.id) },
       inverse_of: :parent_card, :class_name => 'Card', foreign_key: 'parent_card_id'
belongs_to :parent_card, class_name: 'Card', foreign_key: "parent_card_id", optional: true

I think you could give this a try, or something near it. Good luck again!