Trivial and fast (does not execute count or any other unneeded requests) Ruby / Rails / Sinatra / Lux pagination

paginate.rb

# @list = Paginate.set User, size: 40, name: :upage
# Paginate.render @list
# using: https://github.com/dux/html-tag/

module Paginate
  extend self

  def set rset, opts={}
    opts[:size] ||= 20
    opts[:name] ||= :page
    opts[opts[:name]] ||= Current.request.params[opts[:name]] || 1

    size = opts[:size].to_i
    page = opts[opts[:name]].to_i

    # minimal recordset size is 5
    size = 5 if size < 5

    # default page is 1
    page = 1 if page < 1

    # get scope in array form with +1 record to see if we have a next one
    data = rset
      .offset((page - 1) * size)
      .limit(size + 1)
      .to_a

    # do we have a next page?
    has_next =
      if data.length > size
        data.pop
        true
      else
        false
      end

    # inject variables in data array
    data.define_singleton_method(:paginate_page) { page }
    data.define_singleton_method(:paginate_size) { size }
    data.define_singleton_method(:paginate_next) { has_next }
    data.define_singleton_method(:paginate_name) { opts[:name] }
    data
  end

  def render rset
    return unless rset.respond_to?(:paginate_size)
    return nil if rset.paginate_page == 1 && !rset.paginate_next

    HtmlTagBuilder.div(class: :paginate) do |n|
      n.div do |n|
        if rset.paginate_page > 1
          url = Url.current
          rset.paginate_page == 1 ? url.delete(rset.paginate_name) : url.qs(rset.paginate_name, rset.paginate_page-1)

          n.a(href: url.relative) { '&larr;' }
        else
          n.span { '&larr;' }
        end

        n.i rset.paginate_page == 1 ? '&bull;' : rset.paginate_page

        if rset.paginate_next
          url = Url.current
          url.qs(rset.paginate_name, rset.paginate_page+1)
          n.a(href: url.relative) { '&rarr;' }
        else
          n.span { '&rarr;' }
        end
      end
    end
  end
end

paginate.scss

.paginate {
  clear: both;
  padding: 40px 0;
  text-align:center;

  div {
    border:1px solid #ddd;
    display:inline-block;
    border-radius:4px;
    margin:0 auto;
    background-color: #fff;

    i, span, a {
      display:inline-block;
      width:40px;
      padding:10px;
      text-align:center;
      text-decoration:none;
      color:#aaa;
    }
    i {
        border-left:1px solid #eee;
        border-right:1px solid #eee;
    }
    a {
      color:#444;

      &:hover { background-color: #f7f7f7; }
    }
  }
}