Question

关于将Devise gem添加到Rails，我正在关注tutorial。 gem的一个特征是使用Devise生成“用户”，用于进一步的用户身份验证（Facebook，Twitter等）。我遇到了以下错误：

== 20150906025001 AddDeviseToUsers: migrating =================================
-- change_table(:users)
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:

SQLite3::SQLException: duplicate column name: email: ALTER TABLE "users" ADD "email" varchar DEFAULT '' NOT
NULL/Users/jaker/.rvm/gems/ruby-2.0.0-p643/gems/sqlite3-1.3.10/lib/sqlite3/database.rb:91:in `initialize'

我的应用中已经有一个用户模型，有一个电子邮件，所以这是有道理的。但是，当我尝试运行迁移并删除我的“用户”表时，我仍然遇到同样的错误。

[时间戳] _add_devise_to_users.rb：

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

有谁知道如何解决这个问题？我真的很困惑，没有任何文件似乎有帮助。非常感谢。

Answer 1

发生此错误是因为您的email模型中已经有一个名为User的列

您可以评论（或删除）该行：

t.string :email,              null: false, default: ""

并且脚本将继续。

如何修复SQLite设计错误

1 个答案: