错误试图部署到heroku (下面的教程) PG:: Error : ERROR:列"password_digest“的关系”用户“已经存在

Question

因此，我正在跟踪http://www.railstutorial.org/book，并且在本地(运行sqlight3)工作正常。

当我尝试时，我会得到以下错误

heroku运行rake db：

这就是错误消息的样子。

运行连接到终端的rake db:migrate .运行4049迁移到AddPasswordDigestToUsers ( 20140817014655 ) == 20140817014655 AddPasswordDigestToUsers:迁移========================= -- add_column(:users，:password_digest，:string) PG::Error:列"password_digest“的关系”用户“已经存在: ALTER "users”添加列"password_digest“字符变化(255个) rake中止！StandardError:发生了一个错误，随后的迁移都被取消了： 错误:错误:关系“用户”的列"password_digest“已经存在: ALTER "users”在execute‘/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.中添加列"password_digest“字符exec' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in块0.8/lib/active_record/connection_adapters/abstract_adapter.rb:442:in block in log' /app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.0.8/lib/active_support/notifications/instrumenter.rb:20:in仪器‘/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract_adapter.rb:437:in log' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:127:in execute’/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract//app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:629:in add_column' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/postgresql/schema_statements.rb:395:in add_column‘schema_statements.rb:360:in block in method_missing' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:601:in block in method_missing' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:601:in in say_with_time’/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:601:in say_with_time' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:621:in method_missing‘迁移中的/app/db/migrate/20140817014655_add_password_digest_to_users.rb:3:in change' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:575:in exec_migration‘/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:559:in block (2 levels) in migrate' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:558:in块/ with_connection' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:557:in：294:在with_connection' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:557:in中迁移‘execute_migration_in_transaction’migrate' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:963:in块中的execute_migration_in_transaction‘block in ddl_transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract/database_statements.rb:203:in块在事务‘/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in within_new_transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract/database_statements.rb:203:in transaction’/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/transactions.rb:209:in transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:1009:in ddl_transaction‘/app/供应商/bundle/ruby/2.0迁移中的.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:962:in execute_migration_in_transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:924:in块‘/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:920:in each' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:920:in迁移’/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:768：在“任务”中的“/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/railties/databases.rake:42:in”块(2个级别)中：up' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:746:in迁移：=> db：up' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:746:in(请参见通过使用-- trace运行任务的完整跟踪)

我已经尝试过heroku :重置DATABASE_URL，然后再尝试。还尝试将/spec、/lib、/script、/features、/cucumber.yml添加到.slugignore中

这就是我的模式的样子：

ActiveRecord::Schema.define(version: 20140818041701) do

  create_table "users", force: true do |t|
    t.string   "name"
    t.string   "email"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "password_digest"
    t.string   "remember_token"
    t.boolean  "admin",           default: false
  end

  add_index "users", ["email"], name: "index_users_on_email", unique: true
  add_index "users", ["remember_token"], name: "index_users_on_remember_token"

end

这就是我的密码摘要迁移的样子。

class AddPasswordDigestToUsers < ActiveRecord::Migration
  def change
    add_column :users, :password_digest, :string
  end
end

Answer 1

您的表中已经有了password_digest列，通过迁移AddPasswordDigestToUsers，您正在尝试创建另一个列，这就是它造成问题的原因。删除迁移AddPasswordDigestToUsers，然后再次运行rake db:migrate。在这种情况下，Sqlite3不会产生任何错误。如果在迁移中编写intege而不是integer，那么如果使用sqlite，就不会产生任何错误。

Answer 2

如果您只是删除密码摘要迁移文件，它将解决部署到heroku的短期问题，但是协作者将无法在本地提取和设置他们的数据库。它们将遇到问题，并可能会创建另一个迁移文件，从而产生同样的问题。

我不确定最好的解决方案，但到目前为止，这似乎对我来说是可行的：

class AddPasswordDigestToUsers < ActiveRecord::Migration
  def change
    if Rails.env == "production"
    else
      add_column :users, :password_digest, :string   
    end
  end
end