ActionController::UnknownFormat When using respond_to do |format| in rails 5 app

Question

I'm trying to render pages in a div on a profiles/show.html.erb to make it dynamic.

I'm constantly getting this error. ActionController::UnknownFormat

for this line in my profiles_controller.rb

def show

   respond_to do |format|
        format.js { render :show_pages }
   end

end 

I've installed the responders gem (according to http://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html#responders it is necessary to do that.

In my profiles/show.html.erb there is only this line.

<div id="pages_content">


</div>

in my views/profiles I have a .js file called show_pages.js.erb

$("#pages_content").html("<%=escape_javascript(render :partial=>"show_pages")%>");

And also in my views/profiles I have this partial _show_pages.html.erb which is the partial that is supposed to open in the `.

** EDIT -- Here is the full trace**

    actionpack (5.1.5) lib/action_controller/metal/mime_responds.rb:203:in `respond_to'
app/controllers/profiles_controller.rb:8:in `show'
actionpack (5.1.5) lib/action_controller/metal/basic_implicit_render.rb:4:in `send_action'
actionpack (5.1.5) lib/abstract_controller/base.rb:186:in `process_action'
actionpack (5.1.5) lib/action_controller/metal/rendering.rb:30:in `process_action'
actionpack (5.1.5) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
activesupport (5.1.5) lib/active_support/callbacks.rb:131:in `run_callbacks'
actionpack (5.1.5) lib/abstract_controller/callbacks.rb:19:in `process_action'
actionpack (5.1.5) lib/action_controller/metal/rescue.rb:20:in `process_action'
actionpack (5.1.5) lib/action_controller/metal/instrumentation.rb:32:in `block in process_action'
activesupport (5.1.5) lib/active_support/notifications.rb:166:in `block in instrument'
activesupport (5.1.5) lib/active_support/notifications/instrumenter.rb:21:in `instrument'
activesupport (5.1.5) lib/active_support/notifications.rb:166:in `instrument'
actionpack (5.1.5) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (5.1.5) lib/action_controller/metal/params_wrapper.rb:252:in `process_action'
activerecord (5.1.5) lib/active_record/railties/controller_runtime.rb:22:in `process_action'
actionpack (5.1.5) lib/abstract_controller/base.rb:124:in `process'
actionview (5.1.5) lib/action_view/rendering.rb:30:in `process'
actionpack (5.1.5) lib/action_controller/metal.rb:189:in `dispatch'
actionpack (5.1.5) lib/action_controller/metal.rb:253:in `dispatch'
actionpack (5.1.5) lib/action_dispatch/routing/route_set.rb:49:in `dispatch'
actionpack (5.1.5) lib/action_dispatch/routing/route_set.rb:31:in `serve'
actionpack (5.1.5) lib/action_dispatch/journey/router.rb:50:in `block in serve'
actionpack (5.1.5) lib/action_dispatch/journey/router.rb:33:in `each'
actionpack (5.1.5) lib/action_dispatch/journey/router.rb:33:in `serve'
actionpack (5.1.5) lib/action_dispatch/routing/route_set.rb:844:in `call'
warden (1.2.7) lib/warden/manager.rb:36:in `block in call'
warden (1.2.7) lib/warden/manager.rb:35:in `catch'
warden (1.2.7) lib/warden/manager.rb:35:in `call'
rack (2.0.4) lib/rack/etag.rb:25:in `call'
rack (2.0.4) lib/rack/conditional_get.rb:25:in `call'
rack (2.0.4) lib/rack/head.rb:12:in `call'
rack (2.0.4) lib/rack/session/abstract/id.rb:232:in `context'
rack (2.0.4) lib/rack/session/abstract/id.rb:226:in `call'
actionpack (5.1.5) lib/action_dispatch/middleware/cookies.rb:613:in `call'
activerecord (5.1.5) lib/active_record/migration.rb:556:in `call'
actionpack (5.1.5) lib/action_dispatch/middleware/callbacks.rb:26:in `block in call'
activesupport (5.1.5) lib/active_support/callbacks.rb:97:in `run_callbacks'
actionpack (5.1.5) lib/action_dispatch/middleware/callbacks.rb:24:in `call'
actionpack (5.1.5) lib/action_dispatch/middleware/executor.rb:12:in `call'
actionpack (5.1.5) lib/action_dispatch/middleware/debug_exceptions.rb:59:in `call'
web-console (3.5.1) lib/web_console/middleware.rb:135:in `call_app'
web-console (3.5.1) lib/web_console/middleware.rb:28:in `block in call'
web-console (3.5.1) lib/web_console/middleware.rb:18:in `catch'
web-console (3.5.1) lib/web_console/middleware.rb:18:in `call'
actionpack (5.1.5) lib/action_dispatch/middleware/show_exceptions.rb:31:in `call'
railties (5.1.5) lib/rails/rack/logger.rb:36:in `call_app'
railties (5.1.5) lib/rails/rack/logger.rb:24:in `block in call'
activesupport (5.1.5) lib/active_support/tagged_logging.rb:69:in `block in tagged'
activesupport (5.1.5) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (5.1.5) lib/active_support/tagged_logging.rb:69:in `tagged'
railties (5.1.5) lib/rails/rack/logger.rb:24:in `call'
sprockets-rails (3.2.1) lib/sprockets/rails/quiet_assets.rb:13:in `call'
actionpack (5.1.5) lib/action_dispatch/middleware/remote_ip.rb:79:in `call'
actionpack (5.1.5) lib/action_dispatch/middleware/request_id.rb:25:in `call'
rack (2.0.4) lib/rack/method_override.rb:22:in `call'
rack (2.0.4) lib/rack/runtime.rb:22:in `call'
activesupport (5.1.5) lib/active_support/cache/strategy/local_cache_middleware.rb:27:in `call'
actionpack (5.1.5) lib/action_dispatch/middleware/executor.rb:12:in `call'
actionpack (5.1.5) lib/action_dispatch/middleware/static.rb:125:in `call'
rack (2.0.4) lib/rack/sendfile.rb:111:in `call'
railties (5.1.5) lib/rails/engine.rb:522:in `call'
puma (3.11.3) lib/puma/configuration.rb:225:in `call'
puma (3.11.3) lib/puma/server.rb:624:in `handle_request'
puma (3.11.3) lib/puma/server.rb:438:in `process_client'
puma (3.11.3) lib/puma/server.rb:302:in `block in run'
puma (3.11.3) lib/puma/thread_pool.rb:120:in `block in spawn_thread'

Can anyone inform me about why I'm getting this error? Is there anything that I should do different?

I'm rather new to coding so I'm still figuring things out.

thanks CG

Answer 1

I think you're using an incorrect use case for format.js here. Have a read of this for how it's intended to be used: from the docs, "a simple example" .

If you add the line format.html above or below format.js , your page will load and the error will go away.

You can render the partial server side using the following:

<div id="pages_content">
  <%= render "show_pages %>
</div>

And then custom Javascript can be placed in the asset pipeline to contain code updating the page on the client side.

Happy to expand on this if you expand a little on the intended use case or have any questions. Otherwise, hope this adds some clarity for now :)