宝石 2.0。与 ActiveRecord 4.1.2 的兼容性问题答案

【问题标题】：Gem 2.0. Compatibility Issue with ActiveRecord 4.1.2宝石 2.0。与 ActiveRecord 4.1.2 的兼容性问题
【发布时间】：2015-03-31 11:50:31
【问题描述】：

我正在尝试连接 mysql 数据库并从该特定数据库中获取数据，但它正在出现错误..，请修复它

代码是：

require 'rubygems'
#require 'mysql'
require 'active_record'


ActiveRecord::Base.establish_connection(
    {
    :adapter => 'mysql',
    :host => 'localhost',
    :database => 'spyware',
    :user => 'root',
    :password => 'sqlpass'
    }
)

class Definition<ActiveRecord::Base
end

defni = Definition.Find(:all)

defni.each do |row|

    print "\n\n".row.name
end

我得到的错误是::

ruby dbconnect.rb
C:/Ruby200/lib/ruby/gems/2.0.0/gems/activerecord-4.1.2/lib/active_record/connection_adapters/connection_specification.rb:190:in `rescue in spec': Specified 'mysql' for database adapter, but the gem is not loaded. Add `gem 'mysql'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord). (Gem::LoadError)
    from C:/Ruby200/lib/ruby/gems/2.0.0/gems/activerecord-4.1.2/lib/active_record/connection_adapters/connection_specification.rb:187:in `spec'
    from C:/Ruby200/lib/ruby/gems/2.0.0/gems/activerecord-4.1.2/lib/active_record/connection_handling.rb:50:in `establish_connection'
    from dbconnect.rb:6:in `<main>'
>Exit code: 1

我使用的gem版本是2.0.14，mysql版本是2.8.1 x86

【问题讨论】：

标签： mysql ruby-on-rails ruby activerecord rubygems

【解决方案1】：

Rails 已经为您提供了答案：将 gem 'mysql' 添加到您的 Gemfile（并确保其版本为 ActiveRecord 要求的最低版本）。阅读错误日志是个好主意！ ;)

【讨论】：

你有没有运行bundle install来安装gemfile中的所有gem？
你能清楚地解释如何运行 bundle install 和 els plz