Associations cause "EMPTY" in Active Admin

Question

So I'm learning more about belongs_to and has_many Associations in Rails and am combining it with ActiveAdmin.

I have created a Model "Semester" and a Model "Field". A Semester has many Fields and a Field belongs to Semester.

My field Class looks like this:

class Field < ApplicationRecord
  belongs_to :semester
  accepts_nested_attributes_for :semester, allow_destroy: true
end

and my Semester class looks like this:

class Semester < ApplicationRecord
  has_many :fields
  accepts_nested_attributes_for :fields, allow_destroy: true
end

Now I registered the Models with active admin with the following two files:

ActiveAdmin.register Field do

  permit_params :name, semesters_attributes: [:name]

end

and

ActiveAdmin.register Semester do

  permit_params :name, :fields, fields_attributes: [ :field_id, :name]

end

And now there are two issues that come up upon proceeding that I absolutely can not ged rid off:

1) If I do not add optional: true after belongs_to :semester I will get an error message "must exist" upon trying to create a new Field with a respective Semester.

2) If I do add optional: true after belongs_to :semester I will be able to create a new Field but the "Semester" will just be "EMPTY" in the new field.

The console output of case 2) will look like this:

Started POST "/admin/fields" for 127.0.0.1 at 2018-08-17 15:23:54 +0200
Processing by Admin::FieldsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"+GPjjNPOv9GsjXnEtEjBcC0xUMHKKC+YpFLfiUFUOgsgBJ+pLCucscrN0YaTk551GFp4K5lBEI2RW1clw2vCWw==", "field"=>{"semester_id"=>"2", "name"=>"MAVT"}, "commit"=>"Create Field"}
  AdminUser Load (0.1ms)  SELECT  "admin_users".* FROM "admin_users" WHERE "admin_users"."id" = ? ORDER BY "admin_users"."id" ASC LIMIT ?  [["id", 1], ["LIMIT", 1]]
  ↳ /home/divepit/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
Unpermitted parameter: :semester_id
   (0.0ms)  begin transaction
  ↳ /home/divepit/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
  Field Create (0.6ms)  INSERT INTO "fields" ("name", "created_at", "updated_at") VALUES (?, ?, ?)  [["name", "MAVT"], ["created_at", "2018-08-17 13:23:54.026418"], ["updated_at", "2018-08-17 13:23:54.026418"]]
  ↳ /home/divepit/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
   (12.2ms)  commit transaction
  ↳ /home/divepit/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
Redirected to http://0.0.0.0:3000/admin/fields/22
Completed 302 Found in 22ms (ActiveRecord: 13.0ms)


Started GET "/admin/fields/22" for 127.0.0.1 at 2018-08-17 15:23:54 +0200
Processing by Admin::FieldsController#show as HTML
  Parameters: {"id"=>"22"}
  AdminUser Load (0.2ms)  SELECT  "admin_users".* FROM "admin_users" WHERE "admin_users"."id" = ? ORDER BY "admin_users"."id" ASC LIMIT ?  [["id", 1], ["LIMIT", 1]]
  ↳ /home/divepit/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
  Field Load (0.1ms)  SELECT  "fields".* FROM "fields" WHERE "fields"."id" = ? LIMIT ?  [["id", 22], ["LIMIT", 1]]
  ↳ /home/divepit/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
  Rendering /home/divepit/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activeadmin-1.3.1/app/views/active_admin/resource/show.html.arb
   (0.1ms)  SELECT COUNT(*) FROM "active_admin_comments" WHERE "active_admin_comments"."resource_type" = ? AND "active_admin_comments"."resource_id" = ? AND "active_admin_comments"."namespace" = ?  [["resource_type", "Field"], ["resource_id", 22], ["namespace", "admin"]]
  ↳ /home/divepit/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
  ActiveAdmin::Comment Exists (0.1ms)  SELECT  1 AS one FROM "active_admin_comments" WHERE "active_admin_comments"."resource_type" = ? AND "active_admin_comments"."resource_id" = ? AND "active_admin_comments"."namespace" = ? LIMIT ? OFFSET ?  [["resource_type", "Field"], ["resource_id", 22], ["namespace", "admin"], ["LIMIT", 1], ["OFFSET", 0]]
  ↳ /home/divepit/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activerecord-5.2.1/lib/active_record/log_subscriber.rb:98
  Rendered /home/divepit/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/activeadmin-1.3.1/app/views/active_admin/resource/show.html.arb (73.4ms)
Completed 200 OK in 77ms (Views: 74.9ms | ActiveRecord: 0.5ms)

Thanks in advance for any tips on how to solve this! :)

Pavan Pavan · Accepted Answer · 2018-08-17T19:04:40

First things first. Your associations are correct, but as per your associations you should not have field_id in semester table. Instead you should have semester_id in fields table. Also you should change semesters_attributes to semester_attributes

Unpermitted parameter: :semester_id

You should permit semester_id in the fields_attributes

fields_attributes: [ :semester_id, :name]

And finally in Rails 5, whenever a belongs_to association is defined, it is required to have the associated record present by default. To avoid this default behavior, you need to add optional: true

Associations cause "EMPTY" in Active Admin

1 Answers