Question

How can I exclude some items in this scope:

scope :within_category, ->(category) { joins(:category).where(:categories => { :id => category }) }

like this:

scope :within_category, ->(category, item_type) { joins(:category).where(:categories => { :id => category }, :id NOT IN item_type.id) }

Answer 1

Try this:

scope :within_category, ->(category, item_type) { joins(:category).where(:categories => { :id => category }).where(self.arel_table[:id].not_in(item_type.id) }