Why does form_helper assume that it should call active_record_helper?

Question

This code in my view triggers an error:

<% remote_form_for(mymodel) do |f| %>
  <%= f.error_messages %>

(mymodel is not an ActiveRecord object)

When I look at the error trace, I see this section which indicates that error_messages in the view translates into error_messages_for in the active_record_helper:

C:/Ruby18/lib/ruby/gems/1.8/gems/
actionpack-2.3.2/lib/action_view/
helpers/active_record_helper.rb:179:in `error_messages_for'

C:/Ruby18/lib/ruby/gems/1.8/gems/
actionpack-2.3.2/lib/action_view/
helpers/form_helper.rb:984:in `error_messages'

Why does the form_helper think that it should call the active_record_helper even though 'mymodel' is not an ActiveRecord object?

Answer 1

The implementation of f.error_messages is in ActiveRecordHelper because it is dependent on the specific format of ActiveRecord::Errors (which, on ActiveRecord::Base subclasses is stored on mymodel.errors).

If you remove the error_messages, it should work. Alternatively, you can create your own class that has the same interface as ActiveRecord::Errors and just substitute that in this case, duck typing style.