Home How can I rename a database column in a Ruby on Rails migration?
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How can I rename a database column in a Ruby on Rails migration?

user1994764
1#
user1994764 Published in 2010-01-02 16:18:42Z

I wrongly named a column hased_password instead of hashed_password.

How do I update the database schema, using migration to rename this column?

Levi
2#
Levi Reply to 2015-12-04 19:18:33Z
rename_column :table, :old_column, :new_column

Update:

You'll probably want to create a separate migration to do this. (Rename FixColumnName as you will)

script/generate migration FixColumnName
# creates  db/migrate/xxxxxxxxxx_fix_column_name.rb

Then edit the migration to do your will.

# db/migrate/xxxxxxxxxx_fix_column_name.rb
class FixColumnName < ActiveRecord::Migration
  def self.up
    rename_column :table_name, :old_column, :new_column
  end

  def self.down
    # rename back if you need or do something else or do nothing
  end
end

An update for Rails 3.1

While, the up and down methods still apply. Rails 3.1 receives a change method that "knows how to migrate your database and reverse it when the migration is rolled back without the need to write a separate down method"

rails g migration FixColumnName

class FixColumnName < ActiveRecord::Migration
  def change
    rename_column :table_name, :old_column, :new_column
  end
end

If you happen to have a whole bunch of columns to rename, or something that would have required repeating the table name over and over again.

rename_column :table_name, :old_column1, :new_column1
rename_column :table_name, :old_column2, :new_column2
...

You could use change_table to keep things a little neater.

class FixColumnNames < ActiveRecord::Migration
  def change
    change_table :table_name do |t|
      t.rename :old_column1, :new_column1
      t.rename :old_column2, :new_column2
      ...
    end
  end
end

Thank you, Luke && Turadg, for bringing up the topic.

Then just db:migrate as usual or however you go about your business.


An update for Rails 4

While creating a Migration as for renaming a column, Rails 4 generates a change method instead of up and down as mentioned in the above answer. The generated change method is as below :

$ > rails g migration ChangeColumnName

which will create a migration file similar to this :

class ChangeColumnName < ActiveRecord::Migration
  def change
    rename_column :table_name, :old_column, :new_column
  end
end
Saghir A. Khatri
3#
Saghir A. Khatri Reply to 2014-02-07 11:34:54Z

http://api.rubyonrails.org/classes/ActiveRecord/Migration.html

Under Available Transformations

rename_column(table_name, column_name, new_column_name):

Renames a column but keeps the type and content.

Peter Mortensen
4#
Peter Mortensen Reply to 2016-03-03 21:51:09Z

IMO, in this case, better use rake db:rollback. Then edit your migration and again type rake db:migrate. However, if you have data in the column you don't want to lose, then use rename_column.

Manish Shrivastava
5#
Manish Shrivastava Reply to 2014-12-10 13:01:24Z

From API:

rename_column(table_name, column_name, new_column_name)

It renames a column but keeps the type and content remains same.

Ruturaj Bisure
6#
Ruturaj Bisure Reply to 2018-02-12 13:57:26Z

As an alternative option, if you are not married to the idea of migrations, there is a compelling gem for ActiveRecord which will handle the name changes automatically for you, Datamapper style. All you do is change the column name in your model (and make sure you put Model.auto_upgrade! at the bottom of your model.rb) and viola! Database is updated on the fly.

https://github.com/DAddYE/mini_record

Note: You will need to nuke db/schema.rb to prevent conflicts

Still in beta phases and obviously not for everyone but still a compelling choice (I am currently using it in two non-trivial production apps with no issues)

Peter Mortensen
7#
Peter Mortensen Reply to 2016-03-03 21:51:47Z

If the present data is not important for you, you can just take down your original migration using:

rake db:migrate:down VERSION='YOUR MIGRATION FILE VERSION HERE'

Without the quotes, then make changes in the original migration and run the up migration again by:

rake db:migrate
Paul Pettengill
8#
Paul Pettengill Reply to 2013-09-14 02:01:38Z

If the column is already populated with data and live in production, I'd recommend a step by step approach, so as to avoid downtime in production while waiting for the migrations.

First I'd create a db migration to add columns with the new name(s) and populate them with the values from the old column name.

class AddCorrectColumnNames < ActiveRecord::Migration
  def up
    add_column :table, :correct_name_column_one, :string
    add_column :table, :correct_name_column_two, :string

    puts 'Updating correctly named columns'
    execute "UPDATE table_name SET correct_name_column_one = old_name_column_one, correct_name_column_two = old_name_column_two"
    end
  end

  def down
    remove_column :table, :correct_name_column_one
    remove_column :table, :correct_name_column_two
  end
end

Then I'd commit just that change, and push the change into production.

git commit -m 'adding columns with correct name'

Then once the commit has been pushed into production, I'd run.

Production $ bundle exec rake db:migrate

Then I'd update all of the views/controllers that referenced the old column name to the new column name. Run through my test suite, and commit just those changes. (After making sure it was working locally and passing all tests first!)

git commit -m 'using correct column name instead of old stinky bad column name'

Then I'd push that commit to production.

At this point you can remove the original column without worrying about any sort of downtime associated with the migration itself.

class RemoveBadColumnNames < ActiveRecord::Migration
  def up
    remove_column :table, :old_name_column_one
    remove_column :table, :old_name_column_two
  end

  def down
    add_column :table, :old_name_column_one, :string
    add_column :table, :old_name_column_two, :string
  end
end

Then push this latest migration to production and run bundle exec rake db:migrate in the background.

I realize this is a bit more involved of a process, but I'd rather do this than have issues with my production migration.

Abram
9#
Abram Reply to 2016-08-09 14:25:51Z

If you need to switch column names you will need to create a placeholder to avoid a duplicate column name error. Here's an example:

class SwitchColumns < ActiveRecord::Migration
  def change
    rename_column :column_name, :x, :holder
    rename_column :column_name, :y, :x
    rename_column :column_name, :holder, :y
  end
end
sunil
10#
sunil Reply to 2013-12-04 14:34:30Z

If your code is not shared with other one, then best option is to do just rake db:rollback then edit your column name in migration and rake db:migrate. Thats it

And you can write another migration to rename the column

 def change
    rename_column :table_name, :old_name, :new_name
  end

Thats it.

Peter Mortensen
11#
Peter Mortensen Reply to 2016-03-03 21:54:00Z

Some versions of Ruby on Rails support to up/down method to migration and if you have up/down method in your migration, then:

def up
    rename_column :table_name, :column_old_name, :column_new_name
end

def down
    rename_column :table_name, :column_new_name, :column_old_name
end

If you have the change method in your migration, then:

def change
    rename_column :table_name, :column_old_name, :column_new_name
end

For more information you can move: Ruby on Rails - Migrations or Active Record Migrations.

Peter Mortensen
12#
Peter Mortensen Reply to 2016-03-03 21:55:06Z

Simply create a new migration, and in a block, use rename_column as below.

rename_column :your_table_name, :hased_password, :hashed_password
Peter Mortensen
13#
Peter Mortensen Reply to 2016-03-03 21:56:04Z

Manually we can use the below method:

We can edit the migration manually like:

  • Open app/db/migrate/xxxxxxxxx_migration_file.rb

  • Update hased_password to hashed_password

  • Run the below command

    $> rake db:migrate:down VERSION=xxxxxxxxx
    

Then it will remove your migration:

$> rake db:migrate:up VERSION=xxxxxxxxx

It will add your migration with the updated change.

Peter Mortensen
14#
Peter Mortensen Reply to 2016-03-03 21:56:42Z

Run the below command to create a migration file:

rails g migration ChangeHasedPasswordToHashedPassword

Then in the file generated in the db/migrate folder, write rename_column as below:

class ChangeOldCoulmnToNewColumn < ActiveRecord::Migration
  def change
     rename_column :table_name, :hased_password, :hashed_password
  end
end
Peter Mortensen
15#
Peter Mortensen Reply to 2016-03-03 21:57:01Z

For Ruby on Rails 4:

def change
    rename_column :table_name, :column_name_old, :column_name_new
end
Sarwan Kumar
16#
Sarwan Kumar Reply to 2016-03-05 05:10:58Z

You have two ways to do this:

  1. In this type it automatically runs the reverse code of it, when rollback.

    def change
      rename_column :table_name, :old_column_name, :new_column_name
    end
    
  2. To this type, it runs the up method when rake db:migrate and runs the down method when rake db:rollback:

    def self.up
      rename_column :table_name, :old_column_name, :new_column_name
    end
    
    def self.down
      rename_column :table_name,:new_column_name,:old_column_name
    end
    
Peter Mortensen
17#
Peter Mortensen Reply to 2016-03-03 21:58:51Z

Open your Ruby on Rails console and enter:

ActiveRecord::Migration.rename_column :tablename, :old_column, :new_column
Peter Mortensen
18#
Peter Mortensen Reply to 2016-03-03 21:59:36Z

Generate the migration file:

rails g migration FixName

# Creates db/migrate/xxxxxxxxxx.rb

Edit the migration to do your will.

class FixName < ActiveRecord::Migration
  def change
    rename_column :table_name, :old_column, :new_column
  end
end
Peter Mortensen
19#
Peter Mortensen Reply to 2016-03-03 22:00:14Z

Generate a Ruby on Rails migration:

$:> rails g migration Fixcolumnname

Insert code in the migration file (XXXXXfixcolumnname.rb):

class Fixcolumnname < ActiveRecord::Migration
  def change
    rename_column :table_name, :old_column, :new_column
  end
end
Packer
20#
Packer Reply to 2016-03-23 05:49:28Z
$:  rails g migration RenameHashedPasswordColumn
invoke  active_record
      create    db/migrate/20160323054656_rename_hashed_password_column.rb

Open that migration file and modify that file as below(Do enter your original table_name)

class  RenameHashedPasswordColumn < ActiveRecord::Migration
  def change
    rename_column :table_name, :hased_password, :hashed_password
  end
end
Hieu Pham
21#
Hieu Pham Reply to 2016-05-21 05:32:00Z

Update - A close cousin of create_table is change_table, used for changing existing tables. It is used in a similar fashion to create_table but the object yielded to the block knows more tricks. For example:

class ChangeBadColumnNames < ActiveRecord::Migration
  def change
    change_table :your_table_name do |t|
      t.rename :old_column_name, :new_column_name
    end
  end
end

This way is more efficient if we do with other alter methods such as: remove/add index/remove index/add column, eg we can do further like:

# Rename
t.rename :old_column_name, :new_column_name
# Add column
t.string :new_column
# Remove column
t.remove :removing_column
# Index column
t.index :indexing_column
#...
Maddie
22#
Maddie Reply to 2016-12-23 16:10:36Z

Run rails g migration ChangesNameInUsers (or whatever you would like to name it)

Open the migration file that has just been generated, and add this line in the method (in between def change and end):

rename_column :table_name, :the_name_you_want_to_change, :the_new_name

Save the file, and run rake db:migrate in the console

Check out your schema.db in order to see if the name has actually changed in the database!

Hope this helps :)

Apoorv
23#
Apoorv Reply to 2017-06-08 18:01:21Z
 def change
    rename_column :table_name, :old_column_name, :new_column_name
  end
Ratnam Yadav
24#
Ratnam Yadav Reply to 2017-10-05 12:02:57Z

Just generate migration using command

rails g migration rename_hased_password

After that edit the migration add following line in change method

rename_column :table, :hased_password, :hashed_password

This should do the trick.

prasanthrubyist
25#
prasanthrubyist Reply to 2017-12-20 12:08:30Z

Rails 5 migration changes

eg:

rails g model Student student_name:string age:integer

if you want to change student_name column as name

Note:- if you not run rails db:migrate

You can do following steps

rails d model Student student_name:string age:integer

This will remove generated migration file, Now you can correct your column name

rails g model Student name:string age:integer

If you migrated(rails db:migrate), following options to change column name

rails g migration RemoveStudentNameFromStudent student_name:string

rails g migration AddNameToStudent name:string

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