super simple way to display most objects for an admin system (array, AR relation, integers, strings, etc.) also links to associated record when possible.

admin_helper.rb

# WHAT IT DOES:

# with these models ->
# book has author
# author has friendly_name method that points to title
# chapter_pages is a hash with keys of chapters, values of the page they start on

# it does these things ->

# object_for_admin(book.author) 
# => <a href="/books/1">Title of Book</a>

# object_for_admin(book.chapters); @narrow_mode = true
# => Chapter 1
# => Chapter 2

# object_for_admin(book.chapters); @narrow_mode = false
# => Chapter 1, Chapter 2

# object_for_admin(book.created_at)
# => 2015-10-29 2:00 PM

# object_for_admin(book.chapter_pages)
# => {
# =>   "Chapter 1": 1,
# =>   "Chapter 2": 40
# => }

def object_for_admin(object)
  friendly_name = object.try(:friendly_name) || object

  case object
  when Array, ActiveRecord::Relation
    separator = @narrow_mode ? '<br>' : ', '
    sanitize object.map {|o| object_for_admin(o) }.join(separator)
  when Hash
    content_tag(:pre) { JSON.pretty_generate(object) }
  when ActiveRecord::Base
    # if your app uses urls like /admin/users/1, use link_to(friendly_name, [:admin, object])
    link_to(friendly_name, object)
  when Time
    object.stamp("2015-01-01 2:20 PM")
  else
    friendly_name.to_s
  end
end