Ransack search on has_one :through (alias)

Question

I'm attempting to use ransack to search for an attribute on a has_one association in a model.
Currently in my model I have:

class SurveyResponse < ActiveRecord::Base
  belongs_to :course_schedule 
  has_one :instructor, through: :course_schedule
  has_one :instructor_user, through: :instructor, foreign_key: "user_id", source: :user 

I want to search by instructor_user's name in my survey response view. Should I be doing this with a ransacker? My understanding of Arel is very limited, but can I do something like this? (I know this doesn't work as it is..)

def self.ransackable_attributes(auth_object)
[
  'created_at',
  'instructor_user_name'
]
end

ransacker :instructor_user_name, type: :string do 
  Arel.sql('string(survey_responses.instructor_user.last_name)')
end 

In my survey response controller I currently have:

def index
  @search_associations = [:course, :user]

  @q = SurveyResponse.where(corporation_id: @corporation.id).ransack(params[:q])

  @q.build_condition

  @survey_responses =  @q.result.includes(:course, :user, :course_schedule, :instructor, :instructor_user).order(created_at: :asc)

  @survey_responses = paginate(@q)
end

Any help, resources, and guidance would be greatly appreciated.

Answer 1

I don't think you need a ransacker specifically. I believe in your view, inside a search_form_for you just simply could do:

<%= f.search_field :instructor_user_name %>

Also, in your controller instead of @survey_responses = paginate(@q) I think you need @survey_responses = paginate(@survey_responses) so you can paginate the responses not the ransack object (could be wrong on this based on what pagination gem you're using).