Adding a method to FormBuilder that calls a helper method that renders a partial

Question

So I've got this helper method, right?

def table_form_field(name_or_options = nil, *args, &block)
  # ...
  render :partial => "snippets/table_form_field", :locals => options
end

It's nice, except sometimes I want to use it with a form builder, and to do that I'd have to call it like this:

table_form_field(:foo, :form_builder => f) do |name|
  f.text_field name
end

It's annoying to have to specify :form_builder manually. So my goal is to extend ActionView::Helpers::FormBuilder and add a new method to it, like so:

class ActionView::Helpers::FormBuilder
  def table_form_field(name_or_options, options, &block)
    if name_or_options.is_a?(Hash)
      name_or_options[:form_builder] = self
    else
      options[:form_builder] = self
    end

    # But... how can I call the helper?
    # Hmm, I'll try this:

    klass = Class.new do
      include ApplicationHelper
    end

    klass.new.send(:table_form_field, name_or_options, options, &block)

    # Thank you, Mario, but your princess is in another castle!
    #
    # Basically, this tries to call render, and for obvious
    # reasons, klass doesn't know how to render.
    #
    # So... what do I do?
  end
end

Answer 1

You can access an instance variable called @template from within form builders so you can just call table_form_field on the @template variable.

For example, I would create a custom form builder that inherits from ActionView::Helpers::FormBuilder

class MyFormBuilder < ActionView::Helpers::FormBuilder
  def table_form_field(*attrs, &block)
    @template.table_form_field(*attrs, &block)
  end
end

Then in your form_for you can tell it to use your custom form builder

<%= form_for @myobject, :builder => MyFormBuilder do |f| %>
  <%= f.table_form_field :myfield do %>
  <% end %>
<%= end %>