Custom Form Builder in Rails 3

Question

I'm trying to write a custom form builder in Rails to (among other things) automatically add a CSS class to each field I create.

I'd like to extend, for example, text_field to add in the class I need. But the code below, which I would expect would just pass behavior to the standard FormBuilder, fails with an error of the wrong number of arguments. "wrong number of arguments (3 for 1..2)"

class BootstrapFormBuilder < ActionView::Helpers::FormBuilder
    def text_field(object_name, method, options = {})
        super(object_name, method, options)
    end
end

If I look at the Rails source, I see the definition of text_field as:

def text_field(object_name, method, options = {})

Help please! (Bonus points if you throw in the code to merge ":class => 'some_class'" into the options hash along the way.

Thanks!

Answer 1

The Rails source you are referring to shows that text_field has two parameters not three. See FormBuilder source from github.

So update your form builder class as:

class BootstrapFormBuilder < ActionView::Helpers::FormBuilder
    def text_field(method, options = {})
        super(method, options)
    end
end

Then the usage of this, including the class option you want to add:

<%= form_for :foo, builder: BootstrapFormBuilder do |f| %>
  <%= f.text_field :foo_field, class: 'bootstrap_text_field' %>
<% end %>

Any options you pass in to the default FormBuilder are also available to this child class, so use the class option as you would for default form builder.