In simple_form view, the submit button is like this:
<%= f.button :submit, \'Save\' %>
We are trying to pass a params subaction
By specifying f.button :button, type: 'submit', we can use the name and value attributes as follows to submit using a single param. Notably, the value submitted (e.g., 'cake') may be different from the button text (e.g., 'The Best Cake').
_form.html.erb
<%= f.button :button, 'The Best Cake', type: 'submit', name: 'dessert_choice', value: 'cake' %>
<%= f.button :button, 'The Best Pie', type: 'submit', name: 'dessert_choice', value: 'pie' %>
Controller
def controller_action
dessert_choice = params[:dessert_choice] # 'cake' or 'pie'
end
This approach avoids the need for hidden inputs as @dax mentioned in the comment above.
Tested on Simple Form 3.3.1 with Rails 4.2.