class Ransack::Search

pre-filled the same way a search_form_for one is.
before calling. Mirror method_missing so a search_form_with field is
says it responds to the reader; `form_with` in particular checks
Rails' form helpers only read a field's value back when the object

def respond_to_missing?(method_id, include_private = false)
  getter_name = method_id.to_s.sub(/=$/, ''.freeze)
  base.attribute_method?(getter_name) ||
    @context.ransackable_scope?(getter_name, @context.object) ||
    super
end