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
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.
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
Best Answer
Step One — Install Ruby with RVM
Before we do anything else, we should run a quick update to make sure that all of the packages we download to our VPS are up to date:
Once that's done, we can start installin g RVM, Ruby Version Manager. This is a great program that lets you use several versions of Ruby on one server; however, in this case, we will just use it to install the latest version of Ruby on the droplet.
If you do not have curl on your system, you can start by installing it:
To install RVM, open terminal and type in this command:
After it is done installing, load RVM. You may first need to exit out of your shell session and start up a new one.
In order to work, RVM has some of its own dependancies that need to be installed. To automatically install them:
rvm requirements You may need to enter your root password to allow the installation of these dependencies.
On occasion the zlib package may be reported as missing. The RVM page describes the issue and the solution in greater detail here.
Step Two — Install Ruby
Once you are using RVM, installing Ruby is easy.
The latest ruby is now installed. However, since we accessed it through a program that has a variety of Ruby versions, we need to tell the system to use the version we just installed by default.
Step Three — Install RubyGems
The next step makes sure that we have all the required components of Ruby on Rails. We can continue to use RVM to install gems; type this line into terminal.
Step Four — Install Rails Once everything is set up, it is time to install Rails. To start, open terminal and type in:
This process may take a while, be patient with it. Once it finishes you will have Ruby on Rails installed on your droplet.