Building options for input fields In the _form partial I have a rather complicated logic which builds necessary options for input fields:

- input_html_params = dynamic_settings_select_options('#service-settings', settings_aps_instance_services_path(parent))

= simple_form_for [:aps, parent, resource] do |f|
  = f.input :service_status, :as =&gt; :readonly_label 
  = f.input :meta_service_meta_id, :collection =&gt; parent.meta_services, :value_method =&gt; :meta_id, :label_method =&gt; :name, :input_html =&gt; input_html_params
  = f.button :submit


The first problem which I see here is getting input_html_params to pass them into input of meta_service_meta_id because it already has a lot of parameters. Even this didn't help us to avoid long string to pass all parameters. What is best practice to avoid this complicity?

As you can see, extracting them to helper methods doesn't solve this problem, so I would like to hear something new.
You should be able to use a Simple Form Custom Input.

As I don't know Simple Form well enough, I don't know if you can access the routes from a custom input class. 

If not, see the answers to these questions: 


Accessing Rails RESTful routes in the model 


and 


Rails, get resource path in model