rake db：使用 mysql2 gem 创建错误（无法为 {"adapter"=>"mysql2" 创建数据库）答案

【问题标题】：rake db:create error with mysql2 gem (Couldn't create database for {"adapter"=>"mysql2")rake db：使用 mysql2 gem 创建错误（无法为 {"adapter"=>"mysql2" 创建数据库）
【发布时间】：2013-11-06 14:16:55
【问题描述】：

我正在尝试在我的 debian 7 机器上启动 rails 4 并与 ruby 2.0 一起运行，但在使用 mysql2 gem 连接到 mysql 数据库时遇到问题。

我已经使用以下命令来设置周围的一切：

\curl -L https://get.rvm.io | bash -s 稳定 rvm 安装红宝石 rvm 使用 ruby --default rvm rubygems 电流 gem install rails --no-ri --no-rdoc

当我尝试运行 rake db:create 时出现以下错误：


no implicit conversion of Fixnum into String
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/mysql2-0.3.13/lib/mysql2/client.rb:58:in `connect'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/mysql2-0.3.13/lib/mysql2/client.rb:58:in `initialize'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/mysql2_adapter.rb:18:in `new'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/mysql2_adapter.rb:18:in `mysql2_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:440:in `new_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:450:in `checkout_new_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:421:in `acquire_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:356:in `block in checkout'
/home/mayrun/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:355:in `checkout'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:265:in `block in connection'
/home/mayrun/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:264:in `connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:546:in `retrieve_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_handling.rb:79:in `retrieve_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_handling.rb:53:in `connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/mysql_database_tasks.rb:8:in `connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/mysql_database_tasks.rb:16:in `create'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:72:in `create'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:86:in `block in create_current'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:182:in `block in each_current_configuration'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:181:in `each'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:181:in `each_current_configuration'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:85:in `create_current'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/railties/databases.rake:20:in `block (2 levels) in '
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:236:in `call'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:236:in `block in execute'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:231:in `each'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:231:in `execute'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:175:in `block in invoke_with_call_chain'
/home/mayrun/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:168:in `invoke_with_call_chain'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:161:in `invoke'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:149:in `invoke_task'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:106:in `block (2 levels) in top_level'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:106:in `each'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:106:in `block in top_level'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:115:in `run_with_threads'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:100:in `top_level'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:78:in `block in run'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:165:in `standard_exception_handling'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:75:in `run'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/bin/rake:33:in `'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/bin/rake:23:in `load'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/bin/rake:23:in `'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/bin/ruby_executable_hooks:15:in `eval'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/bin/ruby_executable_hooks:15:in `'
Couldn't create database for {"adapter"=>"mysql2", "encoding"=>"utf8", "database"=>"myapp_development", "pool"=>5, "username"=>"dev", "password"=>password, "socket"=>"/var/run/mysqld/mysqld.sock"}
no implicit conversion of Fixnum into String
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/mysql2-0.3.13/lib/mysql2/client.rb:58:in `connect'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/mysql2-0.3.13/lib/mysql2/client.rb:58:in `initialize'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/mysql2_adapter.rb:18:in `new'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/mysql2_adapter.rb:18:in `mysql2_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:440:in `new_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:450:in `checkout_new_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:421:in `acquire_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:356:in `block in checkout'
/home/mayrun/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:355:in `checkout'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:265:in `block in connection'
/home/mayrun/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:264:in `connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:546:in `retrieve_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_handling.rb:79:in `retrieve_connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/connection_handling.rb:53:in `connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/mysql_database_tasks.rb:8:in `connection'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/mysql_database_tasks.rb:16:in `create'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:72:in `create'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:86:in `block in create_current'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:182:in `block in each_current_configuration'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:181:in `each'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:181:in `each_current_configuration'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/tasks/database_tasks.rb:85:in `create_current'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/gems/activerecord-4.0.0/lib/active_record/railties/databases.rake:20:in `block (2 levels) in '
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:236:in `call'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:236:in `block in execute'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:231:in `each'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:231:in `execute'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:175:in `block in invoke_with_call_chain'
/home/mayrun/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:168:in `invoke_with_call_chain'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/task.rb:161:in `invoke'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:149:in `invoke_task'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:106:in `block (2 levels) in top_level'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:106:in `each'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:106:in `block in top_level'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:115:in `run_with_threads'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:100:in `top_level'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:78:in `block in run'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:165:in `standard_exception_handling'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/lib/rake/application.rb:75:in `run'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/gems/rake-10.1.0/bin/rake:33:in `'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/bin/rake:23:in `load'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247@global/bin/rake:23:in `'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/bin/ruby_executable_hooks:15:in `eval'
/home/mayrun/.rvm/gems/ruby-2.0.0-p247/bin/ruby_executable_hooks:15:in `'
Couldn't create database for {"adapter"=>"mysql2", "encoding"=>"utf8", "database"=>"myapp_test", "pool"=>5, "username"=>"dev", "password"=>password, "socket"=>"/var/run/mysqld/mysqld.sock"}

深入了解后的检查：

mysql 已启动并运行
mysql 用户名和密码正确。
mysql 正在监听 localhost 和 127.0.0.1
/var/run/mysqld/mysqld.sock文件存在
我查看了 mysql 日志，似乎 mysql2 甚至没有尝试连接。
用较旧、较慢的 mysql gem 替换 mysql2 gem 时，问题就消失了。

我的mysql版本：

$ mysql --version    
mysql  Ver 14.14 Distrib 5.5.31, for debian-linux-gnu (x86_64) using readline 6.2

这是我的数据库/config.yml 文件：


development:
  adapter: mysql2
  encoding: utf8
  database: myapp_development
  pool: 5
  username: dev
  password: password
  host: localhost
  socket: /var/run/mysqld/mysqld.sock

test:
  adapter: mysql2
  encoding: utf8
  database: myapp_test
  pool: 5
  username: dev
  password: password
  socket: /var/run/mysqld/mysqld.sock

production:
  adapter: mysql2
  encoding: utf8
  database: myapp_production
  pool: 5
  username: dev
  password: password
  socket: /var/run/mysqld/mysqld.sock

本地宝石列表：

*** 当地宝石 *** actionmailer (4.0.0) 动作包 (4.0.0) 活动模型（4.0.0）活动记录（4.0.0） activerecord-deprecated_finders (1.0.3) 主动支持 (4.0.0) 雷尔 (4.0.1) 原子（1.1.14）建设者（3.1.4）捆绑器 (1.3.5) 捆绑器卸载 (1.0.2) 咖啡轨（4.0.1）咖啡脚本（2.2.0）咖啡脚本源 (1.6.3) 厄鲁比斯 (2.7.0) 执行js (2.0.2) 可执行挂钩 (1.2.6) 远足 (1.2.3) i18n (0.6.5) jbuilder (1.5.2) jquery-rails (3.0.4) json (1.8.1) 邮件 (2.5.4) 哑剧类型 (1.25) 迷你测试（4.7.5） multi_json (1.8.2) mysql2 (0.3.13) 多语言（0.3.3）机架 (1.5.2) 机架测试（0.6.2）导轨 (4.0.0) 铁路（4.0.0）耙子 (10.1.0) rdoc (3.12.2) rubygems 捆绑器 (1.4.1) rvm (1.11.3.8) 萨斯（3.2.12） sass-rails (4.0.1) sdoc (0.3.20) 链轮 (2.10.0) 链轮导轨 (2.0.1) 雷神 (0.18.1) 线程安全（0.1.3）倾斜 (1.4.1) 树梢 (1.4.15) 涡轮链接 (1.3.0) tzinfo (0.3.38) 丑化者（2.3.0）

已安装的软件包：

$ sudo dpkg -l | grep mysql
ii  libdbd-mysql-perl                  4.021-1+b1                    amd64        Perl5 database interface to the MySQL database
ii  libmysqlclient-dev                 5.5.31+dfsg-0+wheezy1         amd64        MySQL database development files
ii  libmysqlclient18:amd64             5.5.31+dfsg-0+wheezy1         amd64        MySQL database client library
ii  mysql-client                       5.5.31+dfsg-0+wheezy1         all          MySQL database client (metapackage depending on the latest version)
ii  mysql-client-5.5                   5.5.31+dfsg-0+wheezy1         amd64        MySQL database client binaries
ii  mysql-common                       5.5.31+dfsg-0+wheezy1         all          MySQL database common files, e.g. /etc/mysql/my.cnf
ii  mysql-server                       5.5.31+dfsg-0+wheezy1         all          MySQL database server (metapackage depending on the latest version)
ii  mysql-server-5.5                   5.5.31+dfsg-0+wheezy1         amd64        MySQL database server binaries and system database setup
ii  mysql-server-core-5.5              5.5.31+dfsg-0+wheezy1         amd64        MySQL database server binaries
ii  php5-mysql                         5.4.4-14+deb7u5               amd64        MySQL module for php5

【问题讨论】：

将主机从host: localhost 更改为host: 127.0.0.1 是否有效？
不，完全没有效果。服务器正在监听它们。
参数散列中唯一的 Fixnum 是 "pool"=>5（或者您的密码完全是数字？）...这可能是个问题吗？尝试更改 yml pool: '5' %)
是的，我的密码是数字。改变它完全解决了这个问题。谢谢！
github.com/brianmario/mysql2/issues/44

标签： mysql ruby-on-rails ruby gem mysql2

【解决方案1】：

对于那些还在苦苦挣扎的人，记得在单独的终端中运行 mysqld。

【讨论】：

【解决方案2】：

请确保您的 mysql.sock 在 ubuntu 14.04 中是正确的，它位于 /var/run/mysqld/mysqld.sock

【讨论】：