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Rails Rails 使用 mysql2 出现问题

torubylist · 2015年09月23日 · 最后由 u1445594398 回复于 2015年10月23日 · 6438 次阅读

大家好，我是 rails 新手。我安装的 rails 默认数据库是 sqlite3.但是我想用 mysql。于是百度了一下。 先安装了 mysql 的相关工具，server,client.

netstat -tap |grep mysql
tcp        0      0 localhost:mysql         *:*                     LISTEN      11990/mysqld

rails new app  -d mysql
 rails generate controller Site index about help
错误：Gem::LoadError: Specified 'mysql2' for database adapter, but the gem is not loaded. Add `gem 'mysql2'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord).
/root/railsspace/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/connection_specification.rb:177:in `rescue in spec'

我的 Gemfile:

 1 source 'https://rubygems.org'
 4 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 5 gem 'rails', '4.2.3'
 6 # Use mysql as the database for Active Record
 7 gem 'mysql2', '~> 0.4.1'
 9 # Use SCSS for stylesheets
10 gem 'sass-rails', '~> 5.0'
11 # Use Uglifier as compressor for JavaScript assets
12 gem 'uglifier', '>= 1.3.0'
13 # Use CoffeeScript for .coffee assets and views
14 gem 'coffee-rails', '~> 4.1.0'

根据搜的各类帖子，貌似都没有解决掉问题。请问问题出现在哪里？

1 个赞
chenge #1 2015年09月23日

7 gem 'mysql2', '~> 0.3.0' 0.4 据说是有兼容版本问题。

hewe #2 2015年09月23日

这个我碰到过，你的 Rails 是 4.2.x 的吧，你在你的 Gemfile 里面把 gem 'mysql2', '~>0.3.6' ,然后 bundle 一下，就可以解决。

hewe #3 2015年09月23日

#1 楼 @chenge 是的，好像是兼容问题。

torubylist #4 2015年09月23日

#2 楼 @hewe 是的。可是改了之后问题还是没有解决。You have added to the Gemfile:

zhengbotao #6 2015年09月23日

@torubylist

执行过 bundle 命令了么？

torubylist #7 2015年09月23日

#6 楼 @zhengbotao 执行过 bundle update.

Rei #9 2015年09月23日

#5 楼 @torubylist 不行是什么不行，把日志贴上来，主动提供线索，不要让帮助你的人猜。

torubylist #10 2015年09月23日

#9 楼 @rei 

/root/railsspace/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/connection_specification.rb:177:in `rescue in spec': Specified 'mysql2' for database adapter, but the gem is not loaded. Add `gem 'mysql2'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord). (Gem::LoadError)
        from /root/railsspace/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/connection_specification.rb:174:in `spec'
        from /root/railsspace/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_handling.rb:50:in `establish_connection'
        from /root/railsspace/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/railtie.rb:120:in `block (2 levels) in <class:Railtie>'
        from /root/railsspace/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval'
        from /root/railsspace/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook'
        from /root/railsspace/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/lazy_load_hooks.rb:45:in `block in run_load_hooks'
        from /root/railsspace/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/lazy_load_hooks.rb:44:in `each'
        from /root/railsspace/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/lazy_load_hooks.rb:44:in `run_load_hooks'
        from /root/railsspace/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/base.rb:315:in `<module:ActiveRecord>'
        from /root/railsspace/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/base.rb:26:in `<top (required)>'
        from /usr/local/rvm/gems/ruby-2.2.2/gems/spring-1.4.0/lib/spring/application.rb:319:in `active_record_configured?'
        from /usr/local/rvm/gems/ruby-2.2.2/gems/spring-1.4.0/lib/spring/application.rb:251:in `disconnect_database'
        from /usr/local/rvm/gems/ruby-2.2.2/gems/spring-1.4.0/lib/spring/application.rb:97:in `preload'
        from /usr/local/rvm/gems/ruby-2.2.2/gems/spring-1.4.0/lib/spring/application.rb:143:in `serve'
        from /usr/local/rvm/gems/ruby-2.2.2/gems/spring-1.4.0/lib/spring/application.rb:131:in `block in run'
        from /usr/local/rvm/gems/ruby-2.2.2/gems/spring-1.4.0/lib/spring/application.rb:125:in `loop'
        from /usr/local/rvm/gems/ruby-2.2.2/gems/spring-1.4.0/lib/spring/application.rb:125:in `run'
        from /usr/local/rvm/gems/ruby-2.2.2/gems/spring-1.4.0/lib/spring/application/boot.rb:18:in `<top (required)>'
        from /usr/local/rvm/rubies/ruby-2.2.2/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from /usr/local/rvm/rubies/ruby-2.2.2/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from -e:1:in `<main>'
Rei #13 2015年09月23日

Gemfile Gemfile.lock 的内容贴上来。

torubylist #14 2015年09月23日

已解决，谢谢大家。bundle install --no-deployment

hewe #15 2015年09月23日

#4 楼 @torubylist 好吧，我用这种方法解决了。。。

yuanrenkai #16 2015年09月23日

在 Gemfile 中加上 gem "activerecord-jdbcmysql-adapter", :platforms => :jruby
bundle install

试试

u1445594398 #17 2015年10月23日

同事建議我試試 gem 'mysql2', '~> 0.3.20'

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