Extend will_paginate to work with Materialize

will_paginate.rb

#  config/initializers/will_paginate.rb

module WillPaginate
  module ActionView
    def will_paginate(collection = nil, options = {})
      options[:renderer] ||= MaterializeLinkRenderer
      super.try :html_safe
    end

    class MaterializeLinkRenderer < LinkRenderer
      protected

      def html_container(html)
        tag :ul, html, container_attributes
      end

      def page_number(page)
        tag :li,
            link(page, page, rel: rel_value(page)),
            class: (page == current_page ? 'active' : 'waves-effect')
      end

      def previous_or_next_page(page, text, classname)
        c = classname[0..3]
        tag :li,
            link(tag(:i, nil, class: "mdi-navigation-chevron-#{c == 'next' ? 'right' : 'left'}"), page || '#!'),
            class: [c, classname, ('disabled' unless page)].join(' ')
      end

      def gap
        text = @template.will_paginate_translate(:page_gap) { '&hellip;' }
        %(<li><span class="gap">#{text}</span></li>)
      end
    end
  end
end

I add the 'will_paginate' gem and put this file into the initializers directory.
But, when using <%= will_paginate %> I get this error:
undefined method `total_pages' for nil:NilClass
on line 7
Am I using it wrong?

I'm new to rails and working through railstutorial.org - except using Materialise instead of Bootstrap. I'm up to chapter 9.

I fixed it by replacing the content of the will_paginate method with this:

  options, collection = collection, nil if collection.is_a? Hash
  collection ||= infer_collection_from_controller
  options = options.symbolize_keys
  options[:renderer] ||= MaterializeLinkRenderer
  super(collection, options)