Rails app Foreign key error: Administrative user not allowed to delete other users in

Question

When trying to delete a user when logged in as the administrative user, I get the following error in my heroku logs:

2015-03-24T07:47:23.506661+00:00 app[web.1]: Started DELETE "/users/1" for 128.252.25.47 at 2015-03-24 07:47:23 +0000
2015-03-24T07:47:23.534256+00:00 app[web.1]:   SQL (4.4ms)  DELETE FROM "users" WHERE "users"."id" = $1  [["id", 1]]
2015-03-24T07:47:23.517508+00:00 app[web.1]:   User Load (1.3ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1  [["id", 1]]
2015-03-24T07:47:23.541747+00:00 app[web.1]: Completed 500 Internal Server Error in 31ms
2015-03-24T07:47:23.534529+00:00 app[web.1]: PG::ForeignKeyViolation: ERROR:  update or delete on table "users" violates foreign key constraint "fk_rails_274c57dd65" on table "cars"
2015-03-24T07:47:23.534534+00:00 app[web.1]: : DELETE FROM "users" WHERE "users"."id" = $1
2015-03-24T07:47:23.544385+00:00 app[web.1]: : DELETE FROM "users" WHERE "users"."id" = $1):
2015-03-24T07:47:23.544388+00:00 app[web.1]: 
2015-03-24T07:47:23.544384+00:00 app[web.1]: DETAIL:  Key (id)=(1) is still referenced from table "cars".
2015-03-24T07:47:23.544387+00:00 app[web.1]:   app/controllers/users_controller.rb:45:in `destroy'
2015-03-24T07:47:23.544390+00:00 app[web.1]: 
2015-03-24T07:47:23.536639+00:00 app[web.1]:    (1.7ms)  ROLLBACK
2015-03-24T07:47:23.544377+00:00 app[web.1]: 
2015-03-24T07:47:23.510694+00:00 app[web.1]: Processing by UsersController#destroy as HTML
2015-03-24T07:47:23.534532+00:00 app[web.1]: DETAIL:  Key (id)=(1) is still referenced from table "cars".
2015-03-24T07:47:23.510838+00:00 app[web.1]:   Parameters: {"authenticity_token"=>"iKb5lOUvx8qDoGHtVWNgYRL/dIk5zWFU5kiQpWtGOnabA+D7Yg1gj86NHwYKMmFeK5hh4F/3jndyKHHDHApVoQ==", "id"=>"1"}
2015-03-24T07:47:23.515104+00:00 app[web.1]:   User Load (2.5ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1  [["id", 2]]
2015-03-24T07:47:23.544382+00:00 app[web.1]: ActiveRecord::InvalidForeignKey (PG::ForeignKeyViolation: ERROR:  update or delete on table "users" violates foreign key constraint "fk_rails_274c57dd65" on table "cars"

I'm getting the error because of the table "cars" where a user has_many cars, so I think the error isn't with deleting a user but the cars associated with the user. But I don't understand how to fix my database so a user can be deleted.

Here are my schemas:

schema.rb

create_table "cars", force: :cascade do |t|
    t.text     "year"
    t.text     "brand"
    t.text     "model"
    t.text     "vin"
    t.text     "mileage"
    t.integer  "user_id"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.string   "picture"
  end

  add_index "cars", ["user_id"], name: "index_cars_on_user_id"

  create_table "users", force: :cascade do |t|
    t.string   "name"
    t.string   "email"
    t.datetime "created_at",                      null: false
    t.datetime "updated_at",                      null: false
    t.string   "password_digest"
    t.string   "phone"
    t.string   "remember_digest"
    t.boolean  "admin",           default: false
  end

  add_index "users", ["email"], name: "index_users_on_email", unique: true
  add_index "users", ["phone"], name: "index_users_on_phone", unique: true

What should happen to a user's cars when the user is deleted? — Frederick Cheung, Mar 24 '15 at 08:09
The cars should be deleted as well, the entire user profile and cars associated are deleted. — Virge Assault, Mar 24 '15 at 08:13
Add "dependent: :destroy" in the user model for the associated models. — Sachin R, Mar 24 '15 at 08:22

score 5 · Answer 1 · answered Jan 13 '16 at 03:26

To add an alternative for those who don't want to delete associated records (maybe you want to keep the cars records for later use).

class User < ActiveRecord::Base
  ....
  has_many :cars, dependent: :nullify
end

The associated record foreign_key will be set to nil.

Can be useful for people like me landing on your question!

score 2 · Accepted Answer · answered Mar 24 '15 at 08:29

2

Add cascading delete to yout User model:

class User < ActiveRecord::Base
  ....
  has_many :cars, :dependent => :delete_all
end

answered Mar 24 '15 at 08:29

Klaus

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score 0 · Answer 3 · edited May 23 '17 at 11:58

0

creating a migration with

add_foreign_key :identities, :users, on_delete: :cascade

works for me. See also: https://stackoverflow.com/a/36137593/5521564

edited May 23 '17 at 11:58

Community

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answered May 05 '16 at 21:31

Matthias

1,884
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Rails app Foreign key error: Administrative user not allowed to delete other users in

3 Answers3