Rails migration not working on heroku, Model class reported as uninitialized constant

Question

I'm trying to run a migration on heroku and I can't seem to find the problem why my model class is not recognized.

This is my migration:

class AddTestToGoals < ActiveRecord::Migration
  def change
    add_column :goals, :test, :integer, default: 0, null: false
    Goal.reset_column_information
    Goal.all.each { |g| g.update_attribute :test, Goal::PASS }
  end
end

Running it using

heroku run rake db:migrate

and I get this error

uninitialized constant AddTestToGoals::Goal

Anyone knows what the problem is?

EDIT: miss typed before, it's the model which is not recognized, not the constant in it.

HALF WORKAROUND:

Using this (which I found here: http://visibletrap.blogspot.co.il/2011/10/heroku-access-railss-model-in-migration.html)

class AddTestToGoals < ActiveRecord::Migration
  class Goal < ActiveRecord::Base; end
  def change
     add_column :goals, :test, :integer, default: 0, null: false
     Goal.reset_column_information
     Goal.all.each { |g| g.update_attribute :test, Goal::PASS }
  end
end

heroku doesn't complain about not knowing what Goal is which solves half of the problem. but then, Goal::PASS is not recognized.

It seems to be a reference issue. See my answer below and refer to this question: http://stackoverflow.com/questions/3009477/what-is-rubys-double-colon-all-about — Finbarr, Jul 05 '12 at 22:18
Half Workaround has error in later rails - "class definition in method body" — JosephK, Feb 24 '20 at 07:27

score 10 · Answer 1 · answered Jan 22 '13 at 20:56

10

Old question, but I recently experienced something like it which was due to autoloading being disabled by setting

config.threadsafe!

in my environments/staging.rb file. It can be fixed by replacing it with the following

config.threadsafe! unless $rails_rake_task

This should be OK as there is no need for rake tasks to be threadsafe.

answered Jan 22 '13 at 20:56

Simon Thordal

893
10
28

thank u a lot =) recently switched to multithreading in production and somehow didn't connect the issue with it. – meandre Feb 02 '13 at 11:39
Yeah, this caught me out too. Cheers. – Graham Ashton Feb 12 '13 at 12:30
Really, this saved a lot of time :) – Parth Feb 03 '15 at 09:30

Finbarr · Answer 2 · 2012-07-05T22:19:34.090

0

EDIT:

Change all the references to Goal to be prefixed with ::.

::Goal.reset_column_information
::Goal.all.each { |g| g.update_attribute :test, ::Goal::PASS }

edited Jul 05 '12 at 22:19

answered Jul 05 '12 at 22:14

Finbarr

31,350
13
63
94

1

doesn't help. the error is now: "uninitialized constant UserGoal". – Oded Jul 05 '12 at 22:25
Why are you declaring the Goal class inside the ActiveRecord::Migration? – Finbarr Jul 05 '12 at 22:59
In the half workaround? because I read somewhere that it should help. I have no idea why. – Oded Jul 05 '12 at 23:06
Trying this to make it possible to update the attributes of a related-model while doing the migration. – JosephK Feb 24 '20 at 07:29

score 0 · Answer 3 · answered Feb 24 '20 at 07:56

Unless I am missing something, all workarounds above have been blocked in later rails-versions. But one can still take control of their project/work from artificially-imposed constraints, by doing something like:

execute("INSERT INTO table_name (col_name) VALUES (your_values_here))")

Rails migration not working on heroku, Model class reported as uninitialized constant

3 Answers3