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

Question

I wrongly named a column hased_password instead of hashed_password.

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

Answer 1

rename_column :table, :old_column, :new_column 

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 

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For Rails 3.1 use:

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".

See "Active Record Migrations" for more information.

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 

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

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For Rails 4:

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

$ > rails g migration ChangeColumnName 

which will create a migration file similar to:

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