Rails migration file fails - Mysql2::Error: Data truncated for column

Question

I've set up a new migration file:

class ChangeCourseDefaults < ActiveRecord::Migration
  def self.up
    change_column_null :course_objects, :active, false
    change_column_default :course_objects, :active, 0
  end
end

I run it this way on my debian server (rails 4.2.1 ruby 2.1)

sudo bundle exec rake db:migrate:up VERSION=20150720095700 RAILS_ENV=test

Then I got this error:

Mysql2::Error: Data truncated for column 'active' at row 1: ALTER TABLE `course_objects` CHANGE `active` `active` tinyint(1) NOT NULL/var/www/html/test/xyz/vendor/bundle/ruby/2.1.0/gems/activerecord-4..2.1/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:299:in `query'

Whats the problem?

is there any record previously which is already null.? please check — Athar
– Athar, Commented Jul 20, 2015 at 8:50
yes that is why when this line change_column_null :course_objects, :active, false runs it will check for all values and confirm there should not be any null. and here it crashes. but i guess the answer pasted below will solve your problem. — Athar
– Athar, Commented Jul 20, 2015 at 8:58

Gagan Gami · Accepted Answer · 2015-07-20 09:07:41Z

9

You can use change_column_null

class ChangeCourseDefaults < ActiveRecord::Migration
  def change
    change_column_null :table_name, :column_name, false, 0 # set default as 0
  end
end

edited Jul 20, 2015 at 9:07

answered Jul 20, 2015 at 8:51

Gagan Gami

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3 Comments

Felix Over a year ago

I got this error: undefined method

null' for #<ChangeCourseDefaultsNull:0x00000005be8de0>/var/www/html/test/xyz/vendor/bundle/ruby/2.1.0/gems/activerecord-4.2.1/lib/active_record/migration.rb:661:in

block in method_missing'

Athar Over a year ago

replace null with false.

Matthew Hinea Over a year ago

The docs for change_column_null say: "The method accepts an optional fourth argument to replace existing +NULL+s with some other value. Use that one when enabling the constraint if needed, since otherwise those rows would not be valid. Please note the fourth argument does not set a column’s default."

Community · Accepted Answer · 2017-05-23 12:01:06Z

2

class ChangeCourseDefaults < ActiveRecord::Migration
  def change
    change_column_null :course_objects, :active, false, 0
  end
end

reference: change_column_null for existing column

edited May 23, 2017 at 12:01

CommunityBot

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answered Jul 20, 2015 at 9:07

Athar

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1 Comment

Athar Over a year ago

i just added the answer because above has few issues. please accept above answer Felix once it is correct. he has more right.:)

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