rails 5 mysql 适配器问题

Question

我正在尝试在 rails 5 中创建模型并已安装 mysql-community-server。我还安装了 mysql 和 mysql2 gem。但是当我运行 rails generate model Book 低于错误时，

[root@server-linux library]# rails generate model Book
/root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/dependencies.rb:293:in `require': Could not load 'active_record/connection_adapters/mysql_adapter'. Make sure that the adapter in config/database.yml is valid. If you use an adapter other than 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the Gemfile. (LoadError)
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/dependencies.rb:293:in `block in require'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/dependencies.rb:259:in `load_dependency'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/dependencies.rb:293:in `require'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/connection_specification.rb:174:in `spec'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/connection_handling.rb:53:in `establish_connection'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/railtie.rb:125:in `block (2 levels) in <class:Railtie>'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/lazy_load_hooks.rb:45:in `block in run_load_hooks'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/lazy_load_hooks.rb:44:in `each'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-5.0.0/lib/active_support/lazy_load_hooks.rb:44:in `run_load_hooks'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/base.rb:324:in `<module:ActiveRecord>'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/base.rb:24:in `<top (required)>'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:338:in `active_record_configured?'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:259:in `disconnect_database'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:97:in `preload'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:143:in `serve'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:131:in `block in run'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:125:in `loop'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application.rb:125:in `run'
        from /root/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/spring-1.7.2/lib/spring/application/boot.rb:19:in `<top (required)>'
        from /root/.rbenv/versions/2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from /root/.rbenv/versions/2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from -e:1:in `<main>'
[root@server-linux library]#

database.yaml:

[root@server-linux library]# cat config/database.yml
development:
  adapter: mysql2
  database: library_development
  username: root
  password: [password]
  host: localhost

test:
  adapter: mysql2
  database: library_test
  username: root
  password: [password]
  host: localhost

production:
  adapter: mysql2
  database: library_production
  username: root
  password: [password]
  host: localhost

[root@server-linux library]#

版本详情：

[root@server-linux library]# rails -v
Rails 5.0.0
[root@karthick-linux library]# gem list | grep mysql
activerecord-mysql-adapter (0.0.1)
mysql (2.9.1)
mysql2 (0.4.4)
[root@server-linux library]#

我什至使用命令 rails new library -d mysql

创建了应用程序

知道为什么 mysql 适配器连接失败。

Answer 1

检查您的 Gem 文件

在您的 gem 文件中找到 gem 'mysql2'

如果找不到请添加 gem 'mysql2' 然后运行 bundle install 并重新启动服务器。

Answer 2

您是否尝试安装 bundler。我猜测 mysql2 gem 是为不同版本的 ruby 安装的，而不是你当前版本的 ruby。先尝试安装 bundler。

gem install bundler
bundle install   
rails db:migrate
rails g model book

您也不需要 mysql gem，您可以删除它并在 database.yml 文件中使用 mysql2 作为适配器。

rails 5 mysql 适配器问题

rails 5 mysql adapter issue

ruby

mysql

ruby-on-rails

ruby-on-rails-5