ruby-on-rails - rake db :seed 验证失败

Question

我正在学习 hartle 教程的第 12 章。当我运行 bundle exec rake db:seed 时，我得到了这个错误:

ActiveRecord::RecordInvalid: Validation failed: Email has already been taken

我试着运行

rake db:reset
rake db:migrate
rake db:test:prepare

最后

rake db:populate 

但他们并没有解决问题。当我运行 rake db:populate 它给出:

Don't know how to build task 'db:populate'

这是我的 seeds.rb 文件:

    # Users
User.create!(name:  "Example User",
             email: "example@railstutorial.org",
             password:              "foobar",
             password_confirmation: "foobar",
             admin:     true,
             activated: true,
             activated_at: Time.zone.now)

99.times do |n|
  name  = Faker::Name.name
  email = "example-#{n+1}@railstutorial.org"
  password = "password"
  User.create!(name: name,
              email: email,
              password:              password,
              password_confirmation: password,
              activated: true,
              activated_at: Time.zone.now)
end

# Microposts
users = User.order(:created_at).take(6)
50.times do
  content = Faker::Lorem.sentence(5)
  users.each { |user| user.microposts.create!(content: content) }
end

# Following relationships
users = User.all
user  = users.first
following = users[2..50]
followers = users[3..40]
following.each { |followed| user.follow(followed) }
followers.each { |follower| follower.follow(user) }

我想问题可能出在这一行 email = "example-#{n+1}@railstutorial.org"

Answer 1

你的问题是 rake db:reset 不仅删除并重新创建数据库，而且 it also migrates and seeds it as well .所以基本上发生的事情是这样的:

rake db:drop
rake db:create
rake db:schema:load # (think of this as running all the migrations you've run before)
rake db:seed # (creates your 100 database users)

然后你运行:

rake db:migrate # (likely unnecessary, but it causes no harm)
rake db:test:prepare # (prepares the test database)
rake db:prepare # (runs the seeds AGAIN and causes your errors)

很明显，如果你停止运行 rake db:prepare 命令，你的问题就会消失。然而，为了避免将来发生这些事情，我强烈建议在你的种子文件中加入一些逻辑。它只是 Ruby，因此您可以将 User 创建的内容包装在 unless 语句中，例如:

unless User.find_by( email: "example@railstutorial.org" )
  # create all 100 users
end

如果您的生产站点仍在使用种子数据(例如 SiteSetting 表)，这将证明特别有值(value)；您需要确保数据进入您的生产数据库，但您将创建重复的记录(或错误)再次运行种子而不丢失。

作为您问题答案的附加引用，请参阅 this one 的选定答案。 .

我希望这提供了您需要的所有信息!