Using Ransack to sort attributes for parent of par

Question

I know how to use Ransack's awesome sort_link method for parent attributes, but when I extrapolate the same logic to the attributes of the grandparent, it's not working (I can click the link, just no sorting happens).

Hierarchy goes like this: Signup has_many Request has_many Transaction. I'm searching in from the Transaction perspective.

Controller code:

def index
  @q = Transaction.ransack(params[:q])
  @transactions = @q.result.includes(:request => :signup)
end

View code:

<th><%= sort_link(@q, 'requests.signup.email', "Email") %></th>
<th><%= sort_link(@q, 'requests.pickupdate', "Pick up date") %></th>
<th><%= sort_link(@q, 'requests.returndate', "Returndate") %></th>

Incidentally, the search code (e.g., :request_returndate_eq) is fine, it's just the sorting that's not working.

Model code:

class Signup < ActiveRecord::Base
  has_many :requests
end

class Request < ActiveRecord::Base
  belongs_to :signup
  has_many :transactions, dependent: :destroy
end

class Transaction < ActiveRecord::Base
  belongs_to :request
end

Console output

On first click to sort ascending (though with any click it always produces a 200 response, even though the view doesn't actually change)

Started GET "/admin/transactions?q%5Bs%5D=requests.signups.email+asc" for 127.0.0.1 at 2014-07-07 13:40:16 -0700
  Processing by TransactionsController#index as HTML
    Parameters: {"q"=>{"s"=>"requests.signups.email asc"}}
    Rendered layouts/_flash.html.erb (0.6ms)
      (0.4ms)  SELECT "transactions"."name" FROM "transactions"
    Transaction Load (0.6ms)  SELECT "transactions".* FROM "transactions"
    Request Load (0.3ms)  SELECT "requests".* FROM "requests"  WHERE "requests"."id" IN (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
    Signup Load (0.1ms)  SELECT "signups".* FROM "signups"  WHERE "signups"."id" IN (4, 5, 1, 2)
  Rendered transactions/index.html.erb within layouts/application (74.3ms)
Completed 200 OK in 85ms (Views: 81.7ms | ActiveRecord: 1.4ms)

Answer 1

You can using delegate to avoid parent or parent expression in view.

Model

class Transaction < ActiveRecord::Base
  belongs_to :request
  delegate :email, to: :request, prefix: true
end

Transaction View code:

<th><%= sort_link(@q, 'request_email', "Email") %></th>