在Ruby Nitrouis IO中将`gem'mysql2'`添加到您的Gemfile中以实现无轨项目

Question

我为mysql2和Active Record安装了gems。 当我运行代码时，出现错误：

/usr/local/opt/rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/activerecord-4.2.4/lib/active_record/connection_adapters/connection_specification.rb:177:in` `rescue in spec': Specified 'my sql2' 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 /usr/local/opt/rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/activerecord-4.2.4/lib/active_record/connection_adapters/connection_specification.rb:174:in `spec'
        from `/usr/local/opt/rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/activerecord-4.2.4/lib/active_record/connection_handling.rb:50:in `establish_connection'

这是我的代码：

require 'mysql2'
require 'active_record'

client = Mysql2::Client.new(:host => "localhost", :username => "root")

client.query("show databases").each do |db|
  p db
end

ActiveRecord::Base.establish_connection(
  adapter: 'mysql2',
  databases: 'store_manager'
)

错误是说我需要将sql2添加到我的gemfile中。 在哪里可以找到它，我需要添加什么吗？

Answer 1

您可以在项目的根目录下创建Gemfile。 这应该允许您使用mysql2 gem。

Answer 2

对于Active Record 4.2.4，您需要使用以下版本的mysql gem：

gem "mysql2", "~> 0.3.18"