how to call javascript functions from the controller in rails - ruby-on-rails

Question

I'm trying to call a javascript function (actually coffeescript) from a controller in a Rails 3.2 app.
I'm getting a Render and/or redirect were called multiple times in this action error.
My code looks like this:
#Model.controller
def index
#models = Model.all
my_action if current_user.name == "Bob" #or some other general conditional
...and some stuff
respond_to do |format|
format.html
format.js #this is needed to handle ajaxified pagination
end
end
def my_action
respond_to do |format|
format.js { render :js => "my_function();" } #this is the second time format.js has been called in this controller!
end
end
#functions.js.coffee.erb
window.my_function = ->
i = xy
return something_amazing
What is the correct way to call a js function from the controller?

Answer 1

Man, you missed argument for block. Primary mistake.
def my_action
#respond_to do # This line should be
respond_to do |format|
format.js { render :js => "my_function();" }
end
end
And MrYoshiji's point is right. But your error was on server side, had not reached client side yet.
For the style, I think that's okay if the js code is one function call only. If more JS code, it's better to render js template
# controller
format.js
# app/views/my_controller/my_action.js.erb
my_function();
// and some more functions.
Update: How to fix double rendering problem
You must have your #index return if condition met, or the method will continue to execute and cause rendering twice or more. Fix it like this:
def index
#models = Model.all
if current_user.name == "Bob"
return my_action
else
# ...and some stuff
respond_to do |format|
format.html
format.js #this is needed to handle ajaxified pagination
end
end