Question

I’m just getting started with rails gems, and wondering how best to add functionality to existing rails modules. For example, if I wanted to add a new form helper, I’d typically do something like this:

class ActionView::Helpers::FormBuilder
  # My form defs in here
end

But I’m wondering if that’s the most elegant way of doing things – especially if, for example, I’m going to wrap the new functionality up in a gem.

For example, suppose I’m creating the gem “MyGem”, and I only want its functionality to be present if the gem is called in the controller. So in the controller I add ‘include MyGem’, and in the lib/my_gem.rb I’d typically do something like:

# lib/my_gem.rb
module MyGem
  # My form defs in here
end

The question is: what is the standard way for overwriting defs in the ActionView::Helpers::FormBuilder module from within the MyGem module?

Cheers…

Answer 1

If you create a Class with inheritance of ActionView::Helpers::FormBuilder you can override all method from FormBuilder you want.

You can add other method too.

After you just need use this FormBuilder when you create your form with option :builder Or you can do an helper method like simple_form_for to call the form_for method with your builder.

If you want do in a module you need create your class in module

# lib/my_gem.rb
require 'my_gem/form_builder'

# lib/my_gem/form_builder.rb
module MyGem
  class FormBuilder < ActionView::Helpers::FormBuilder
    # form def
  end
end

In your builder you use :builder => MyGem::FormBuilder