mysql2 gem 的 Gem::LoadError，但它已经在 Gemfile 中 [英] Gem::LoadError for mysql2 gem, but it's already in Gemfile

问题描述

Gem::LoadError
Specified 'mysql2' for database adapter, but the gem is not loaded.
Add `gem 'mysql2'` to your Gemfile

加载以下文件时发生此错误:

This error occurred while loading the following files:

active_record/base

这是我在运行 rails 服务器时遇到的错误.

This is the error I get on running rails server.

The mysql2 gem has been added to the Gemfile as well.

我已经完成了bundle install，并尝试重新启动服务器，但仍然出现错误.

I've done bundle install, and tried restarting the server but still get the error.

推荐答案

如果您在升级到 rails 4.2.4(也有 rails 4.1.5)时遇到此错误，请尝试使用此版本的 mysql2:

If you have this error when upgrading to rails 4.2.4 (also with rails 4.1.5) try using this version of mysql2:

gem 'mysql2', '~> 0.3.18'

显然 mysql2 仍然与较新版本的 rails 不兼容，因为在我 2015 年 9 月 8 日回答这个问题时，rails 4.2.4 还很新，所以在您的 Gem 文件中使用上面的行并运行:

Apparently mysql2 isn't still compatible with newer version of rails because rails 4.2.4 is pretty new as the time of answering this question by me 8 September 2015 so use the above line in your Gem file and run:

bundle install 

你应该没事了

这篇关于mysql2 gem 的 Gem::LoadError，但它已经在 Gemfile 中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！