What's the correct syntax for remove_index in a Rails 3.1.0 migration?

Question

I\'m in the process of adding Devise to an existing Rails app, with a Users table already defined. The devise generator pushed out the following migration:

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Answer 1

To alter a table and/or its indeces use #change_table inside #change action of a migration. Then you be able to create reversable index removal as follows:

def change
   change_table :users do |t|
      t.index :email, :unique => true
      t.index :reset_password_token, :unique => true
   end
end

When you have to drop a table with its index of course with reversable action you can use #drop_table method for SchemaStatements with the #index method of Table class for ConnectionAdapter:

def change
   drop_table :users do |t|
      t.index :email, :unique => true
      t.index :reset_password_token, :unique => true
   end
end

In case you have need exactly the #up/down pair in a migration. Use just a #change_table method along with #remove_index method of Table class for ConnectionAdapter:

def up
   change_table :users do |t|
      t.index :email, :unique => true
      t.index :reset_password_token, :unique => true
   end
end

def down
   change_table :users do |t|
      t.remove_index :email, :unique => true
      t.remove_index :reset_password_token, :unique => true
   end
end

All of the methods are available in Rails version of 2.1.0 or of earlier ones.