will_paginate and SEO prev next head link tags

will_paginate_seo_helper.rb

#put it into one of your app/helpers files
# you have to replace the collection_path with the path of your model!
# tag.link only works from rails 5.1 ... prior you have to use content_tag ...
# next - prev links header
  def pagination_head_tags(collection)
    if collection.total_pages
      link_tags = ""
      if collection.current_page < collection.total_pages
        link_tags += tag.link  nil, href: collection_path(page: collection.current_page + 1),  rel: "next"
      end
      if collection.current_page > 1
        link_tags += tag.link  href: collection_path(page: collection.current_page - 1),  rel: "prev"
      end
      link_tags.html_safe
    end
  end