How to pass an array from a form to a controller method?

There are more solutions to it but I prefer this one:

In the model for which the form is for add:

attr_accessor :order_ids

Now in the haml code i.e., in the form add:

%input{name: "model_name[order_ids][]", type: "hidden", value: order}

And in the controller in:

params[:model_name][:order_ids]

you should get the array. Just change the model_name to the name of you model.

And why are you sending:

= f.submit "Save Changes", :method => :sort

method as sort. This is not correct. If you want to send the form to the action sort in your controller then that needs to be specified in the form url

Suppose you have a action named sort in lists_controller and in your routes you define it as:

put '/sort', to: 'lists#sort', as: list_sort

Then in the form you can give it as:

= form_for @list, :html => { :method => :put, :multipart => true, url: list_sort_path } do |f|

Hope this helps.