0

ich would like to ask for some help with has_and_belongs_to_many association.

I have the following tables and models:

candidate_job_title_translations -> Candidate::JobTitleTranslation (in a subfolder with table_name_prefix ) 

create_table "candidate_job_title_translations", force: :cascade do |t|
end

profile_experiences, ProfileExperience

create_table "profile_experiences", id: :serial, force: :cascade do |t|
end

candidate_job_title_translations_profile_experiences, No model

create_table "candidate_job_title_translations_profile_experiences", id: false, force: :cascade do |t|
    t.bigint "candidate_job_title_translation_id", null: false
    t.bigint "profile_experience_id", null: false
end

The two models are setuped for the association:

class ProfileExperience < ApplicationRecord
   has_and_belongs_to_many :candidate_job_title_translations, class_name: 'Candidate::JobTitleTranslation'
end

class Candidate::JobTitleTranslation < ApplicationRecord
   has_and_belongs_to_many :profile_experiences, class_name: 'ProfileExperience'
end

My Problem now is, I get a ActiveRecord error, saying job_title_translation_id does not exist, which is correct. It should look for candidate_job_title_translation_id

ActiveRecord::StatementInvalid: PG::UndefinedColumn: ERROR:  column candidate_job_title_translations_profile_experiences.job_title_translati
on_id does not exist
LINE 1: ...ces" ON "candidate_job_title_translations"."id" = "candidate...

I have the feeling I can solve it by not having the table_name_prefix and model structure but, that is not good in terms of my structure. Maybe you have an idea.

Thanks

Alexander Bahlk
  • 75
  • 1
  • 9
  • Can you please post the full server error? You cut out some vital pieces :) – gwalshington Mar 07 '18 at 15:06
  • @gwalshington I have the issue in the test, while accessing: 'profile_experience.candidate_job_title_translations' – Alexander Bahlk Mar 07 '18 at 15:35
  • Well, my initial thought is why is it combining 2 tables into 1 on the query. Look at the output of the server `candidate_job_title_translations_profile_experiences` - what does the call look like? Why are `candidate_job_title_translations` and `profile_experiences` being combined into one? You'd think the error is that `job_title_translation_id` doesn't exist, but the real issue may be that the table you're querying doesn't exist? Hope that helps :) – gwalshington Mar 07 '18 at 16:23
  • Ruby on Rails style guide recommends (and for good reasons) to avoid `HABTM` relationships and prefer regular `has_many` `through` instead. – MrYoshiji Mar 07 '18 at 16:54
  • @MrYoshiji true, the reason for my HABTM was to prevent a relationship model – Alexander Bahlk Mar 07 '18 at 18:10
  • @gwalshington I moved the model now to the root model folder and all works – Alexander Bahlk Mar 07 '18 at 18:11

1 Answers1

1

Thats not really a good domain model to start with.

If you want a translations table you want to do it something like:

class Position
  belongs_to :title
  has_many :translated_titles, 
    through: :title,
    source: :translations
end

class Title
  has_many :positions
  has_many :translations, 
    class_name: 'Titles::Translation'
end

class Titles::Translation
  belongs_to :title
end

You should be more concerned about creating meaningful relations and duplication than "I don't want to have another class, waaah" which is the most common reason for choosing HABTM.

Also when "namespacing" models in Rails the module should be plural:

Good: Titles::Translation
Bad: Title::Translation

This convention is due to the way that ActiveRecord maps tables to tables to classes and the fact that nesting your model inside another model class is not really a good idea.

max
  • 96,212
  • 14
  • 104
  • 165