Question

所以我在rails中有一些迁移问题..我有2个迁移，一个用于添加users表，另一个用于向用户添加设计...

现在我尝试运行

时出现此错误

rake db:migrate

ActiveRecord::StatementInvalid: SQLite3::SQLException: duplicate column name: email: ALTER TABLE "users" ADD "email" varchar DEFAULT '' NOT NULL

告诉我两个迁移都试图将列电子邮件添加到users表中。

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

添加到用户迁移的设备

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

我假设它的

add_index :users, :email,                unique: true

在第二次迁移中导致这个问题...但我只是好奇......这条线甚至与设计相关吗？我在文档中找不到与此相关的任何内容...所以如果我要删除那两行会对设计的运行方式产生影响吗？

Answer 1

您正尝试两次创建列email：在您自己的迁移和设计中。此外，您不需要password_digest列。第二次因为列已经存在而出现错误。

我的建议是在创建用户之前回滚版本（rake db：rollback VERSION = timestamp_from_migration_filename），从CreateUsers中删除email和password_digest，然后重试所有迁移。

Answer 2

change_column helper用于对单个表进行多次更改。它总是尝试添加列。

请查看api-dock

上的详细信息

Rake db：使用Devise迁移副本

2 个答案: