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rake db:create出现问题

ruby-on-railsrubyrubygemsrbenv
3

我认为这是一个常见问题，但是我尝试了几篇其他帖子中提到的方法，却遇到了相同的命运。

我使用rbenv是因为这是我最先发现的。

rake db:create
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/connection_adapters/connection_specification.rb:177:in `rescue in spec'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/connection_adapters/connection_specification.rb:174:in `spec'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/connection_handling.rb:50:in `establish_connection'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/tasks/mysql_database_tasks.rb:8:in `establish_connection'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/tasks/mysql_database_tasks.rb:15:in `create'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/tasks/database_tasks.rb:93:in `create'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/tasks/database_tasks.rb:107:in `block in create_current'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/tasks/database_tasks.rb:275:in `block in each_current_configuration'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/tasks/database_tasks.rb:274:in `each'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/tasks/database_tasks.rb:274:in `each_current_configuration'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/tasks/database_tasks.rb:106:in `create_current'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.4/lib/active_record/railties/databases.rake:17:in `block (2 levels) in <top (required)>'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/task.rb:240:in `call'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/task.rb:240:in `block in execute'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/task.rb:235:in `each'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/task.rb:235:in `execute'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/task.rb:179:in `block in invoke_with_call_chain'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/task.rb:172:in `invoke_with_call_chain'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/task.rb:165:in `invoke'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/application.rb:150:in `invoke_task'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/application.rb:106:in `block (2 levels) in top_level'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/application.rb:106:in `each'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/application.rb:106:in `block in top_level'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/application.rb:115:in `run_with_threads'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/application.rb:100:in `top_level'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/application.rb:78:in `block in run'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/application.rb:176:in `standard_exception_handling'
    /Users/cmunger/.rbenv/versions/2.2.3/lib/ruby/2.2.0/rake/application.rb:75:in `run'
    /Users/cmunger/.rbenv/versions/2.2.3/bin/rake:33:in `<main>'
    Couldn't create database for {"adapter"=>"mysql2", "encoding"=>"utf8", "pool"=>5, "username"=>"blogApp", "password"=>"*****", "socket"=>"/tmp/mysql.sock", "database"=>"blog_test"}
    rake aborted!
    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).

Gem::LoadError: can't activate mysql2 (~> 0.3.13), already activated mysql2-0.4.2. Make sure all dependencies are added to Gemfile

我的版本和Bundle安装程序。mysql2已经存在...

cmunger@Claytons-Mac:~/Desktop/Devlopment/blog$ rbenv versions
  system
* 2.2.3 (set by RBENV_VERSION environment variable)
cmunger@Claytons-Mac:~/Desktop/Devlopment/blog$ bundle install
Using actionmailer 4.2.4
Using actionpack 4.2.4
Using actionview 4.2.4
Using activejob 4.2.4
Using activemodel 4.2.4
Using activerecord 4.2.4
Using activesupport 4.2.4
Using arel 6.0.3
Using binding_of_caller 0.7.2
Using builder 3.2.2
Using bundler 1.10.6
Using byebug 8.2.1
Using coffee-rails 4.1.0
Using coffee-script 2.4.1
Using coffee-script-source 1.10.0
Using concurrent-ruby 1.0.0
Using debug_inspector 0.0.2
Using erubis 2.7.0
Using execjs 2.6.0
Using globalid 0.3.6
Using i18n 0.7.0
Using jbuilder 2.3.2
Using jquery-rails 4.0.5
Using json 1.8.3
Using loofah 2.0.3
Using mail 2.6.3
Using mime-types 2.99
Using mini_portile2 2.0.0
Using minitest 5.8.3
Using multi_json 1.11.2
Using mysql2 0.4.2
Using nokogiri 1.6.7
Using rack 1.6.4
Using rack-test 0.6.3
Using rails 4.2.4
Using rails-deprecated_sanitizer 1.0.3
Using rails-dom-testing 1.0.7
Using rails-html-sanitizer 1.0.2
Using railties 4.2.4
Using rake 10.4.2
Using rdoc 4.2.0
Using sass 3.4.20
Using sass-rails 5.0.4
Using sdoc 0.4.1
Using spring 1.5.0
Using sprockets 3.5.2
Using sprockets-rails 2.3.3
Using thor 0.19.1
Using thread_safe 0.3.5
Using tilt 2.0.1
Using turbolinks 2.5.3
Using tzinfo 1.2.2
Using uglifier 2.7.2
Using web-console 2.2.1
Bundle complete! 12 Gemfile dependencies, 54 gems now installed.
Use `bundle show [gemname]` to see where a bundled gem is installed.

我认为以下错误可能是问题的根源：

我认为以下错误可能是问题的根源:

Gem::LoadError: can't activate mysql2 (~> 0.3.13), already activated mysql2-0.4.2. Make sure all dependencies are added to Gemfile

我尝试将其改回，但我得到了以下内容：
gem 'mysql2', '~> 0.4.2'
ERROR:  While executing gem ... (Gem::CommandLineError)
    Unknown command mysql2,

如果您需要任何进一步的信息，请随时询问。我是按照使用rbenv安装的维基百科上的指导进行操作的，现在进行到这个阶段了。

5个回答
8

除非您正在运行Rails 4.2.5或更高版本，否则您需要将以下内容放入您的中：

gem 'mysql2', '~> 0.3.10'

来源：mysql gem兼容性列表

3

您需要在命令中添加bundle exec，否则您将在全局 gemset 上执行它：

bin/rake db:create

作为一种替代方式，您可以使用 binstubs：
bundle exec rake db:create
你只需要在 Gemfile 中添加 mysql2 宝石，然后运行 bundle install。 - Yury Lebedev
@YuryLebedev，我认为您在答案中颠倒了代码片段的顺序。 - benjamin
@benjamin你的意思是binstubs是首选方式吗？我也这么认为，但想让答案更贴近最初的问题。 - Yury Lebedev
@YuryLebedev，mysql2在这里http://pastebin.com/sumedqk2。仍然出现以下错误：Gem :: LoadError：指定数据库适配器“mysql2”，但未加载宝石。将gem' mysql2'添加到您的Gemfile中（并确保其版本至少符合ActiveRecord所需的最低要求）。Gem :: LoadError：无法激活mysql2（〜> 0.3.13），已经激活mysql2-0.4.2。确保将所有依赖项添加到Gemfile中。 - Kirs Kringle
我已经解决了这个问题，方法是进入 gem 文件并将 mysql2 更改为 gem 'mysql2'，'~> 0.3.18'，然后运行 bundle install。 - Kirs Kringle
显示剩余2条评论
2

对于Rails 4.2.5或更高版本，请使用以下内容

gem 'mysql2', '~> 0.3.18'

那么。
bundle install
1

在你的Gemfile中，现在只使用以下内容：

gem mysql2

在您的命令行中运行：
$ gem install -v '0.3.13'
$ bundle exec bundle update
$ bundle exec bundle install
0

对于那些尝试了以上所有方法仍然面临相同问题的人，我有一点额外的建议。

我最初尝试了以下步骤：

  1. 安装rbenv
  2. 将rbenv global和rbenv local设置为所需版本
  3. 在我的项目中创建一个设置为所需版本的.ruby-version文件
  4. 将建议的rbenv条目放入我的.bash_profile中
  5. 使用rbenv version测试我的设置并得到了我期望的结果
  6. 尝试了这个线程上建议的许多其他方法

但是没有任何作用。

最终，在头痛和尝试不同方法数小时后，最终解决问题的方法是重新启动。所以只是一个提示：如果所有这些建议都失败了，请不要像我一样浪费几个小时：只需重新启动。

我第一次遇到这个问题是在运行bundle install时。上述rbenv步骤加上重新启动解决了问题。然后，即使在同一个bash会话中bundle install仍然有效，问题也出现在rails db:create命令上！再次检查了所有内容，最终解决问题的方法是重新启动。

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