Render does not work after call to update function in Rails - ruby-on-rails

Question

My controller's update function looks like this:
def update
#cohort = Cohort.find(params[:cohort][:id])
#cohort.update_attributes(params[:cohort])
respond_to do |format|
format.js {render action: "show", layout: "courses"}
end
end
When I trigger the update function (via js), get the following in my Rails console:
Started PUT "/cohorts/41" for 127.0.0.1 at 2014-07-18 21:57:26 -0400
Processing by CohortsController#update as */*
Parameters: {"cohort"=>{"id"=>"41", "user_id"=>"17", "room_id"=>"16"}, "id"=>"41"}
Cohort Load (0.1ms) SELECT "cohorts".* FROM "cohorts" WHERE "cohorts"."id" = ? LIMIT 1 [["id", "41"]]
(0.0ms) begin transaction
(0.3ms) UPDATE "cohorts" SET "room_id" = 16, "updated_at" = '2014-07-18 21:57:26.303928' WHERE "cohorts"."id" = 41
(8.5ms) commit transaction
User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 17 LIMIT 1
Course Load (0.1ms) SELECT "courses".* FROM "courses" WHERE "courses"."id" = 21 LIMIT 1
Timeperiod Load (0.1ms) SELECT "timeperiods".* FROM "timeperiods" WHERE "timeperiods"."id" = 37 LIMIT 1
CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = 17 LIMIT 1
User Load (0.2ms) SELECT "users".* FROM "users" WHERE (role = 'faculty' OR role = 'admin')
FacultyReport Load (0.1ms) SELECT "faculty_reports".* FROM "faculty_reports" WHERE "faculty_reports"."cohort_id" = 41 LIMIT 1
Room Load (0.1ms) SELECT "rooms".* FROM "rooms"
Room Load (0.1ms) SELECT "rooms".* FROM "rooms" WHERE "rooms"."id" = 16 LIMIT 1
Enrollment Load (0.1ms) SELECT "enrollments".* FROM "enrollments" WHERE "enrollments"."cohort_id" = 41
CACHE (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = 17 LIMIT 1
Rendered cohorts/show.html.erb within layouts/courses (12.3ms)
Rendered layouts/_header.html.erb (2.1ms)
Rendered layouts/_leftnav.html.erb (0.8ms)
Rendered layouts/_messages.html.erb (0.1ms)
Completed 200 OK in 44.7ms (Views: 31.1ms | ActiveRecord: 10.0ms)
Notice it says Rendered cohorts/show.html.erb within layouts/courses (12.3ms). In the browser itself, no refresh or re-rendering occurs. If I manually refresh the page, I can see the changes were made but the page itself change.
Also, if I change render to redirect_to I get (in the console) a redirect loop that goes for about 14 iterations and then stops and no changes in the browser.

Answer 1

respond_to
From your comments & looking at your code, you need to remember how Rails repond_to block works
When you call format.js, Rails will automatically look for [action_name].js.erb in your views/controller folder. This file will essentially run when you hit the update action from ajax / JS, it will perform the function & then look for update.js.erb to run.
You have several issues with your code:
#app/controllers/your_controller.rb
Class YourController < ApplicationController
def update
#cohort = Cohort.find(params[:cohort][:id])
#cohort.update_attributes(params[:cohort])
respond_to do |format|
format.js {render layout: "courses"} #-> automatically loads views/your_controller/update.js.erb
end
end
end
--
Update
Something else you should consider is your update functionality - specifically that you're trying to update a model with naked params (you should use strong_params):
def update
#cohort = Cohort.find params[:cohort][:id]
#cohort.update(cohort_params)
end
private
def cohort_params
params.require(:cohort).permit(:your, :params)
end
Edit:
I changed format.js {render action: "show", layout: "courses"} to format.js {render "update.js.erb"} and it works as intended.