mysql2 ruby​​ 2.3.1安装错误使用

Question

我对Ruby不是很专业。当我尝试在本地运行我的应用程序时，它应该运行良好，但事实并非如此。当我启动服务器

rails s

它说

=> Booting Unicorn
=> Rails 4.2.3 application starting in development on http://localhost:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
Exiting
/home/lukni/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/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 /home/lukni/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/connection_specification.rb:174:in `spec'
    from /home/lukni/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-4.2.3/lib/active_record/connection_handling.rb:50:in `establish_connection'
    from /home/lukni/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-4.2.3/lib/active_record/railtie.rb:120:in `block (2 levels) in <class:Railtie>'
    from /home/lukni/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.3/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval'
    from /home/lukni/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.3/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook'
    from /home/lukni/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-4.2.3/lib/active_support/lazy_load_hooks.rb:28:in `block in on_load'

我正在使用Ruby 2.3.1

我需要在我的本地启动我的应用程序。

Answer 1

在rails项目文件夹中，您应该有一个名为Gemfile的文件。

因此，只需在此文件中添加以下行：gem 'mysql2'根据此错误消息：Add gem 'mysql2' to your Gemfile (and ensure its version is at the minimum required by ActiveRecord

添加之后，请不要忘记通过bundle install命令更新您的宝石。

如果你遇到一些问题，最好从mysql2 gem guideline安装所有必需的步骤。