Single Table Inheritance + Relationships

Question

I'm creating a rails 5 application (a sort of job finder that connects recruiters with applicants).

Here is a part of my model configuration:

class User < ActiveRecord::Base
  has_and_belongs_to_many :tag
end

class Applicant < User
  has_many :experience
  has_many :match
end

class Recruiter < User
  has_one :company
  has_many :offer
end

class Experience < ActiveRecord::Base
  belongs_to :applicant, :foreign_key => "user_id"
  has_one :company
end

And these are extracts from my schema file:

create_table "users", force: :cascade do |t|
    t.string "type", null: false
    t.string "login", limit: 40, null: false
    t.string "password", limit: 500, null: false
    t.bigint "company_id"

    t.index ["company_id"], name: "index_users_on_company_id"
    t.index ["login"], name: "index_users_on_login", unique: true
  end

create_table "experiences", force: :cascade do |t|
    t.string "job_name", limit: 100, null: false
    t.bigint "company_id"
    t.bigint "user_id", null: false
    t.text "description"
    t.index ["company_id"], name: "index_experiences_on_company_id"
    t.index ["job_name"], name: "index_experiences_on_job_name"
    t.index ["user_id"], name: "index_experiences_on_user_id"
  end

add_foreign_key "users", "companies"
add_foreign_key "experiences", "companies"
add_foreign_key "experiences", "users"

An Experience is attached to the model Applicant through the table user (which contain a type field for the STI), this is why I specified "foreign_key => 'user_id'" in Experience model.

My problem is when I try to access at the first experience of an applicant, I get this error:

PG::UndefinedColumn: ERROR: column experiences.applicant_id does not exist LINE 1: SELECT "experiences".* FROM "experiences" WHERE "experiences...

I hope you can help me. Thanks!

Answer 1

As stated in the docs:

By convention, Rails assumes that the column used to hold the foreign key on the other model is the name of this model with the suffix _id added.

Try doing:

class Applicant < User
  has_many :experiences, foreign_key: :user_id
  has_many :matches
end

Note that it is conventional to use the plural with the has_many association.

BTW, it's no obvious to me why you're using STI, but I'm sure there are good reasons.