Scopes chaining by OR

Question

How can I DRY these scopes?

 scope :reputed, -> {
 joins{reputations.outer}.
 where{['coalesce(rs_reputations.value, 0) > ? OR purchases.force_active = ?', LOWEST_VOTE, true]}
 }
 scope :reputed_or_mine, ->(user) {
 joins{reputations.outer}.
 where{['coalesce(rs_reputations.value, 0) > ? OR purchases.force_active = ? OR purchases.user_id = ?', LOWEST_VOTE, true, user.id]}
 }

Answer 1

'coalesce(rs_reputations.value, 0) > ? OR purchases.force_active = true OR (? AND purchases.user_id = ?)',
LOWEST_VOTE,
!user.id.nil?,
(if user.id.nil? then -1 else user.id end)

This is semantically equivalent to both, but the AND in the third clause prevents it from having an effect when there is no user.id.

• Mike Samuel: @ck3g, can you be more specific about the errors?
• ck3g: Sure. user.id will throw error Undefined method id for NilClass or called id for nil... if user will not passed. Your solution is based on this.
• Mike Samuel: @ck3g, Understood. In that case, I'd declare the user argument with a default value that has an id of nil.
• Simon B.: with OR in there, you don't get much other options. I don't support collecting in several steps and merging afterwards, because that's what a relational database is usually the best at. So I'm upvoting this solution.