The usual way to build a relation in a ActiveSupport::Concern Show archive.org snapshot is this:
module MyModule
extend ActiveSupport::Concern
included do
scope :disabled, -> { where(disabled: true) }
end
end
However, if you have a association with a polymorphic model, where you have to select based on the kind of record, using included like this will not produce the wanted results:
module MyModule
extend ActiveSupport::Concern
included do
has_many :tasks,
-> { where concrete_mission_type: self.class.name },
foreign_key: :mission_id,
inverse_of: :mission
end
end
> mission.tasks.to_sql
"SELECT \"tasks\".* FROM \"tasks\" WHERE \"tasks\".\"mission_id\" = 735 AND \"tasks\".\"concrete_mission_type\" = 'ActiveRecord::Relation'"
You can fix that through using self.included(subclass) in your concern:
module MyModule
extend ActiveSupport::Concern
def self.included(subclass)
subclass.class_eval do
has_many :tasks,
-> { where concrete_mission_type: subclass.name },
foreign_key: :mission_id,
inverse_of: :mission
end
super
end
end
> mission.tasks.to_sql
"SELECT \"tasks\".* FROM \"tasks\" WHERE \"tasks\".\"mission_id\" = 737 AND \"tasks\".\"concrete_mission_type\" = 'ConspirationFinder'"
If you want to know more about self.included, see this card.
Posted by Judith Roth to makandra dev (2021-04-30 13:06)