Extracting queries from controller to model

Question

I had a complex query in the controller like:

def outgoing_tasks
 @tasks = current_user.
 assigned_tasks.
 uncompleted.
 includes(executor: :profile).
 order("deadline DESC").
 paginate(page: params[:page], per_page: Task.pagination_per_page)
end

and since I have some other collections in that controller I refactored to this:

def outgoing_tasks
 @tasks = current_user.assigned_tasks.assigned_default(page: params[:page])
end

with these new methods in the model:

def self.ordered
 order("deadline DESC")
end
def self.paginated(page: 1)
 paginate(page: page, per_page: self.pagination_per_page)
end
def self.assigned_default(page: 1)
 uncompleted.includes(executor: :profile).ordered.paginated(page: page)
end

Should I do something differently or is this okay?

Answer 1

This is a good place to use scopes. http://edgeguides.rubyonrails.org/active_record_querying.html#scopes Scopes are just syntactic sugar for class methods that return relations. In this way they can always be chain-able.

scope :ordered -> { order(deadline: 'DESC') }
scope :paginated -> (page: 1) { paginate(page: page, per_page: pagination_per_page) }
scope :assigned_default -> (page: 1) { uncompleted.includes(executor: :profile).ordered.paginated(page: page) }

• Szilard Magyar: kjprice, I checked out a few repos (for instance the upcase.com by thoughtbot) and the guys using scopes only for where clauses. For some reason they use class methods for these. Can you guess why are they doing that way?
• kjprice: I could only speculate. Maybe they've decided on a style that they think is more readable? -- I for instance, see the pattern of scope :for -> (task) { where(task: task) } a lot. But I find that to be a unnecessary abstraction.