Active Admin Show Page for one model is not working - ruby-on-rails

Question

I am integrating Active Admin into a Ruby on Rails app. I registered all my models and already set up index, filter and show for all the models. Everything is working, but for one model the admin/show page is not running.
When calling the show page from the admin/index page, I get:
NoMethodError in Admin/safts#show
Showing /Users/xxxxxx/.rvm/gems/ruby-1.8.7-p374#xxxxxx/gems/activeadmin-0.6.0/app/views/active_admin/resource/show.html.arb where line #1 raised:
undefined method `empty?' for #<Keyword:0x105498800>
Extracted source (around line #1):
1: insert_tag renderer_for(:show)
Request
Parameters:
{"id"=>"9"}
The relative entry in my log file is:
Started GET "/admin/safts/9" for 127.0.0.1 at Sun Feb 25 14:48:04 +0100 2018
Processing by Admin::SaftsController#show as HTML
Parameters: {"id"=>"9"}
[1m[35mAdminUser Load (0.6ms)[0m SELECT `admin_users`.* FROM `admin_users` WHERE `admin_users`.`id` = 2 LIMIT 1
[1m[36mSaft Load (0.2ms)[0m [1mSELECT `safts`.* FROM `safts` WHERE `safts`.`id` = ? LIMIT 1[0m [["id", "9"]]
[1m[35mKeyword Load (0.3ms)[0m SELECT `keywords`.* FROM `keywords` WHERE `keywords`.`id` = 138 LIMIT 1
Rendered /Users/xxxxxx/.rvm/gems/ruby-1.8.7-p374#xxxxxx/gems/activeadmin-0.6.0/app/views/active_admin/resource/show.html.arb (3.1ms)
Completed 500 Internal Server Error in 10ms
ActionView::Template::Error (undefined method `empty?' for #<Keyword:0x1052a0890>):
1: insert_tag renderer_for(:show)
activemodel (3.2.5) lib/active_model/attribute_methods.rb:407:in `method_missing'
activerecord (3.2.5) lib/active_record/attribute_methods.rb:149:in `method_missing'
activeadmin (0.6.0) lib/active_admin/views/pages/show.rb:38:in `default_title'
activeadmin (0.6.0) lib/active_admin/views/pages/show.rb:14:in `title'
activeadmin (0.6.0) lib/active_admin/views/pages/base.rb:25:in `build_active_admin_head'
arbre (1.0.1) lib/arbre/context.rb:92:in `with_current_arbre_element'
arbre (1.0.1) lib/arbre/element/builder_methods.rb:49:in `within'
activeadmin (0.6.0) lib/active_admin/views/pages/base.rb:24:in `build_active_admin_head'
activeadmin (0.6.0) lib/active_admin/views/pages/base.rb:9:in `build'
arbre (1.0.1) lib/arbre/element/builder_methods.rb:30:in `build_tag'
arbre (1.0.1) lib/arbre/context.rb:92:in `with_current_arbre_element'
arbre (1.0.1) lib/arbre/element/builder_methods.rb:26:in `build_tag'
arbre (1.0.1) lib/arbre/element/builder_methods.rb:39:in `insert_tag'
activeadmin (0.6.0) app/views/active_admin/resource/show.html.arb:1:in `___sers__tephan__rvm_gems_ruby_______p____somesite_gems_activeadmin_______app_views_active_admin_resource_show_html_arb___1026777847_2195984600'
arbre (1.0.1) lib/arbre/context.rb:45:in `instance_eval'
arbre (1.0.1) lib/arbre/context.rb:45:in `initialize'
activeadmin (0.6.0) app/views/active_admin/resource/show.html.arb:1:in `new'
activeadmin (0.6.0) app/views/active_admin/resource/show.html.arb:1:in `___sers__tephan__rvm_gems_ruby_______p____somesite_gems_activeadmin_______app_views_active_admin_resource_show_html_arb___1026777847_2195984600'
actionpack (3.2.5) lib/action_view/template.rb:145:in `send'
actionpack (3.2.5) lib/action_view/template.rb:145:in `render'
activesupport (3.2.5) lib/active_support/notifications.rb:125:in `instrument'
.
.
.
script/rails:6:in `gem_original_require'
script/rails:6:in `require'
script/rails:6
Rendered /Users/xxxxxx/.rvm/gems/ruby-1.8.7-p374#xxxxxx/gems/actionpack-3.2.5/lib/action_dispatch/middleware/templates/rescues/_trace.erb (0.7ms)
Rendered /Users/xxxxxx/.rvm/gems/ruby-1.8.7-p374#xxxxxx/gems/actionpack-3.2.5/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (0.6ms)
Rendered /Users/xxxxxx/.rvm/gems/ruby-1.8.7-p374#xxxxxx/gems/actionpack-3.2.5/lib/action_dispatch/middleware/templates/rescues/template_error.erb within rescues/layout (9.8ms)
The rails model is:
class Saft < ActiveRecord::Base
attr_accessible :colour, :cover_alt, :description, :number, :short, :title_id
# Associations
has_and_belongs_to_many :keywords, :join_table => "safts_keywords"
has_many :authors, :through => :texts
has_many :texts
belongs_to :title, :class_name => "Keyword", :foreign_key => "title_id"
has_one :cover
has_many :stamps
has_many :images
end
The ActiveAdmin resource is:
ActiveAdmin.register Saft do
index do
column "Issue", :number
column "Title", :title_id do |saft|
link_to saft.title.word.capitalize, saft_path(saft)
end
column :short
column :description
column :colour
column :cover_alt
default_actions
end
# Filter only by:
filter :title_id, :label => 'Title', :as => :select, :collection => Saft.all.map{|u| ["#{u.title.word.capitalize}", u.id]}
filter :short
form do |f|
f.inputs "Saft Details" do
f.input :number, :label => "Number of issue"
f.input :title_id, :label => 'Title', :as => :select, :collection => Keyword.all.map{|u| ["#{u.word.capitalize}", u.id]}
f.input :short
f.input :description
f.input :colour, :label => "Colour (in hex)"
f.input :cover_alt
end
f.actions
end
show do
panel "Saft Details" do
attributes_table_for saft do
row :id
row :number
row :title_id
row :short
row :description
row :colour
row :cover_alt
row :created_at
row :updated_at
end
end
active_admin_comments
end
end
Just for context: SAFT is a magazine, with texts, images, authors, etc. All the other resources are working well in Admin. Only the show page of SAFT is not working. What could it be?

Answer 1

Your log entry says Keyword does not respond to empty? in Pages::Show#default_title.
default_title calls display_name, have you overridden display_name_methods? In this case you can remove :title
In config/initializers/active_admin:
config.display_name_methods = [ :display_name,
:full_name,
:name,
:username,
:login,
:email,
:to_s ]
Perhaps better in this case you can also try setting the title explicitly, eg.
show title: :short do ...
I notice you are on very old versions of Rails and ActiveAdmin, I hope you will consider upgrading.

Answer 2

I was able to solve the problem, which is related to the associations.
The DisplayHelper Module of the gem has to be modified as follows:
module ActiveAdmin
module ViewHelpers
module DisplayHelper
# Attempts to call any known display name methods on the resource.
# See the setting in `application.rb` for the list of methods and their priority.
def display_name(resource)
resource.send display_name_method_for resource
end
# Looks up and caches the first available display name method.
def display_name_method_for(resource)
##display_name_methods_cache ||= {}
##display_name_methods_cache[resource.class] ||= begin
methods = active_admin_application.display_name_methods - association_methods_for(resource)
methods.detect{ |method| resource.respond_to? method }
end
end
# To prevent conflicts, we exclude any methods that happen to be associations.
def association_methods_for(resource)
return [] unless resource.class.respond_to? :reflect_on_all_associations
resource.class.reflect_on_all_associations.map(&:name)
end
# Return a pretty string for any object
# Date Time are formatted via #localize with :format => :long
# ActiveRecord objects are formatted via #auto_link
# We attempt to #display_name of any other objects
def pretty_format(object)
case object
when String
object
when Arbre::Element
object
when Date, Time
localize(object, :format => :long)
when ActiveRecord::Base
auto_link(object)
else
display_name(object)
end
end
end
end
end
This is because in the SAFT model there is an association with the name title, which goes into conflict with the display_name_method.