##
# limit selected items to one page, get ids of first item before/after the page
def get_page_items(items, includes: [], limit: 20)
+ param! :before, Integer, :min => 1
+ param! :after, Integer, :min => 1
+
id_column = "#{items.table_name}.id"
page_items = if params[:before]
items.where("#{id_column} < ?", params[:before]).order(:id => :desc)