Rake db:migrate duplicate with Devise - ruby-on-rails

Question

So i'm having some issues with migrations in rails.. i have 2 migrations one to add the users table and one to add devise to users...
now im getting this error when i try run
rake db:migrate
ActiveRecord::StatementInvalid: SQLite3::SQLException: duplicate column name: email: ALTER TABLE "users" ADD "email" varchar DEFAULT '' NOT NULL
which tells me that both migrations are trying to add the column email to the users table..
USER TABLE CREATE MIGRATION
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :name
t.string :email
t.string :password_digest
t.timestamps null: false
end
end
end
DEVISE ADDED TO USERS MIGRATION
class AddDeviseToUsers < ActiveRecord::Migration
def self.up
change_table(:users) do |t|
## Database authenticatable
t.string :email, null: false, default: ""
t.string :encrypted_password, null: false, default: ""
## Recoverable
t.string :reset_password_token
t.datetime :reset_password_sent_at
## Rememberable
t.datetime :remember_created_at
## Trackable
t.integer :sign_in_count, default: 0, null: false
t.datetime :current_sign_in_at
t.datetime :last_sign_in_at
t.string :current_sign_in_ip
t.string :last_sign_in_ip
## Confirmable
# t.string :confirmation_token
# t.datetime :confirmed_at
# t.datetime :confirmation_sent_at
# t.string :unconfirmed_email # Only if using reconfirmable
## Lockable
# t.integer :failed_attempts, default: 0, null: false # Only if lock strategy is :failed_attempts
# t.string :unlock_token # Only if unlock strategy is :email or :both
# t.datetime :locked_at
# Uncomment below if timestamps were not included in your original model.
# t.timestamps null: false
end
add_index :users, :email, unique: true
add_index :users, :reset_password_token, unique: true
# add_index :users, :confirmation_token, unique: true
# add_index :users, :unlock_token, unique: true
end
def self.down
# By default, we don't want to make any assumption about how to roll back a migration when your
# model already existed. Please edit below which fields you would like to remove in this migration.
raise ActiveRecord::IrreversibleMigration
end
end
im assuming its the
add_index :users, :email, unique: true
line in the 2nd migration causing this issue... but im just curious... is that line even relevant to devise? i can't find anything relating to this in the documentation... so if I were to delete those 2 lines would that have any effect on the way Devise runs??

Answer 1

You are trying to create column email twice: in your own migration and in devise. Also, you don't need password_digest column. Second time you got an error because the column already exists.
My advice is to rollback on version before creating users (rake db:rollback VERSION=timestamp_from_migration_filename), remove email and password_digest from your CreateUsers and try again all migrations.

Answer 2

change_column helper is for making multiple alteration on a single table. It always try to add column.
Please check the details on api-dock