So… I’ve got a migration (post.rb uses the state_machine gem) class AddVerifiedAtToPost < ActiveRecord::Migration

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Asked: May 28, 20262026-05-28T13:04:36+00:00 2026-05-28T13:04:36+00:00

So… I’ve got a migration (post.rb uses the state_machine gem) class AddVerifiedAtToPost < ActiveRecord::Migration

0

So… I’ve got a migration (post.rb uses the state_machine gem)

class AddVerifiedAtToPost < ActiveRecord::Migration
  def self.up

    add_column :posts, :verified_at, :datetime

    Post.find_each do |post|
      post.update_attribute(:verified_at, post.created_at) unless post.awaiting_verification?
    end

  end

  def self.down
    remove_column :posts, :verified_at
  end
end

… This gives me an undefined method “relation” for nil class…

So I thought– hmm, maybe for some weird reason the state_machine predicate methods are not working in the context of a migration, so I modified the code to do:

    Post.find_each do |post|
      post.update_attribute(:verified_at, post.created_at) unless post.status == "awaiting_verification"
    end

But then I get the error of duplicate column “verified_at” already exists……. Ok— so then I wrap my add_column in a column_exists?, giving me a migration that now looks like:

class AddVerifiedAtToPost < ActiveRecord::Migration
  def self.up

    unless column_exists?(:posts, :verified_at)
      add_column :posts, :verified_at, :datetime
    end

    Post.find_each do |post|
      post.update_attribute(:verified_at, post.created_at) unless post.status == "awaiting_verification"
    end

  end

  def self.down
    remove_column :posts, :verified_at
  end
end

… Run rake db:migrate… it succeeds.. hooray… But I am still skeptical, so I run rake db:migrate:down VERSION=

and then run rake db:migrate again, guess what?

==  AddVerifiedAtToPost: migrating ============================================
-- column_exists?(:posts, :verified_at)
   -> 0.0048s
-- add_column(:posts, :verified_at, :datetime)
   -> 0.0644s
rake aborted!
An error has occurred, all later migrations canceled:

undefined method `column' for nil:NilClass

(See full trace by running task with --trace)

… I run rake db:migrate again, it works… I do rake db:migrate:down again, and then rake db:migrate– get the same error……..

So I tried an experiment.. I ran rake db:migrate:down, removed the column.. Hopped into the console and did ActiveRecord::Migration.add_column(:posts, :verified_at, :datetime)

Ran the migration– no errors.. It seems that for some reason add_column in the context of this migration file is being all weirdo on me.

this is the stack trace:

** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute db:migrate
==  AddVerifiedAtToPost: migrating ============================================
-- column_exists?(:posts, :verified_at)
   -> 0.0052s
-- add_column(:posts, :verified_at, :datetime)
   -> 0.0805s
rake aborted!
An error has occurred, all later migrations canceled:

undefined method `column' for nil:NilClass
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activesupport-3.0.7/lib/active_support/whiny_nil.rb:48:in `method_missing'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/arel-2.0.10/lib/arel/nodes/unqualified_column.rb:8:in `column'
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/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/arel-2.0.10/lib/arel/visitors/visitor.rb:15:in `send'
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/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/arel-2.0.10/lib/arel/tree_manager.rb:20:in `to_sql'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/arel-2.0.10/lib/arel/crud.rb:20:in `update'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/persistence.rb:255:in `update'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/locking/optimistic.rb:77:in `update'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/attribute_methods/dirty.rb:68:in `update'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/timestamp.rb:60:in `update'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/callbacks.rb:281:in `update'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:419:in `_run_update_callbacks'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/callbacks.rb:281:in `update'
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/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:220:in `_conditional_callback_around_270'
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/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/callbacks.rb:273:in `create_or_update'
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/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/validations.rb:43:in `save'
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/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/transactions.rb:240:in `save_without_unsaved_flag'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/transactions.rb:292:in `with_transaction_returning_status'
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/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/migration.rb:312:in `send'
/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@myapp/gems/activerecord-3.0.7/lib/active_record/migration.rb:312:in `migrate'
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/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@global/gems/rake-0.8.7/bin/rake:31
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/Users/patrick/.rvm/gems/ree-1.8.7-2011.03@global/bin/rake:19

note, I also commented out all the post model’s before/after save/create callbacks to see if that was some how triggering this, and it’s not…

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1 Answer

Editorial Team · Answer 1 · 2026-05-28T13:04:36+00:00

Editorial Team

2026-05-28T13:04:36+00:00Added an answer on May 28, 2026 at 1:04 pm

Call “reset_column_information” before playing with changed columns

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So… I’ve got a migration (post.rb uses the state_machine gem) class AddVerifiedAtToPost < ActiveRecord::Migration

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