Thinner Rails Model with the Finder Pattern

Hello everybody, today I want to share with you a pattern learned from gitlab: the finder pattern.

Most of the time when you want to find an item based on a set of different conditions you do something like this:

class Project
  		def issues_for_user_filtered_by(user, filter)
		# A lot of logic not related to project model itself
  		end
end

By doing that you end up having a lot of methods that does not really belong to the Model logic. A better solution is through the finder pattern:

issues = IssuesFinder.new(project, user, filter).execute

What the finder does is to accept a set of parameters and return an ActiveRecord::Associations::CollectionProxy that you can use for further filtering/mapping operations.

You can find a complete example of a finder following this link