Gem::LoadError: 为数据库适配器指定了“postgresql”，但未加载 gem答案

【问题标题】：Gem::LoadError: Specified 'postgresql' for database adapter, but the gem is not loadedGem::LoadError: 为数据库适配器指定了“postgresql”，但未加载 gem
【发布时间】：2016-12-31 07:35:14
【问题描述】：

帮帮我！输入“mina deploy”得到这个美感：

我的“/home/deploy/inscope/shared/config/database.yml”看起来：

production:
  adapter: postgresql
  encoding: unicode
  database: ***
  username: ***
  password: ***
  host: localhost

rake aborted!
   Gem::LoadError: Specified 'postgresql' for database adapter, but the gem is not loaded. Add `gem 'pg'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord).
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activerecord-4.1.0/lib/active_record/connection_adapters/connection_specification.rb:190:in `rescue in spec'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activerecord-4.1.0/lib/active_record/connection_adapters/connection_specification.rb:187:in `spec'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activerecord-4.1.0/lib/active_record/connection_handling.rb:50:in `establish_connection'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activerecord-4.1.0/lib/active_record/railtie.rb:129:in `block (2 levels) in <class:Railtie>'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/lazy_load_hooks.rb:28:in `block in on_load'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/lazy_load_hooks.rb:27:in `each'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/lazy_load_hooks.rb:27:in `on_load'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activerecord-4.1.0/lib/active_record/railtie.rb:118:in `block in <class:Railtie>'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/initializable.rb:30:in `instance_exec'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/initializable.rb:30:in `run'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/initializable.rb:55:in `block in run_initializers'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/initializable.rb:54:in `run_initializers'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/application.rb:288:in `initialize!'
   /home/deploy/inscope/tmp/build-142737137923106/config/environment.rb:5:in `<top (required)>'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `require'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `block in require'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:232:in `load_dependency'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `require'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/application.rb:264:in `require_environment!'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/application.rb:367:in `block in run_tasks_blocks'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/sprockets-rails-2.2.4/lib/sprockets/rails/task.rb:64:in `block (2 levels) in define'
   Gem::LoadError: pg is not part of the bundle. Add it to Gemfile.
   /home/deploy/.rvm/gems/ruby-2.2.0/gems/bundler-1.9.1/lib/bundler/rubygems_integration.rb:261:in `block in replace_gem'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activerecord-4.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:13:in `<top (required)>'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `require'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `block in require'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:232:in `load_dependency'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `require'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activerecord-4.1.0/lib/active_record/connection_adapters/connection_specification.rb:188:in `spec'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activerecord-4.1.0/lib/active_record/connection_handling.rb:50:in `establish_connection'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activerecord-4.1.0/lib/active_record/railtie.rb:129:in `block (2 levels) in <class:Railtie>'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/lazy_load_hooks.rb:28:in `block in on_load'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/lazy_load_hooks.rb:27:in `each'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/lazy_load_hooks.rb:27:in `on_load'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activerecord-4.1.0/lib/active_record/railtie.rb:118:in `block in <class:Railtie>'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/initializable.rb:30:in `instance_exec'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/initializable.rb:30:in `run'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/initializable.rb:55:in `block in run_initializers'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/initializable.rb:54:in `run_initializers'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/application.rb:288:in `initialize!'
   /home/deploy/inscope/tmp/build-142737137923106/config/environment.rb:5:in `<top (required)>'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `require'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `block in require'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:232:in `load_dependency'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:247:in `require'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/application.rb:264:in `require_environment!'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/railties-4.1.0/lib/rails/application.rb:367:in `block in run_tasks_blocks'
   /home/deploy/inscope/tmp/build-142737137923106/vendor/bundle/ruby/2.2.0/gems/sprockets-rails-2.2.4/lib/sprockets/rails/task.rb:64:in `block (2 levels) in define'
   Tasks: TOP => environment
   (See full trace by running task with --trace)

！错误：部署失败。
-----> 清理构建
断开电流好的

！命令失败。失败，状态为 19

【问题讨论】：

你能展示你的 gem 文件中的内容吗？您是否指定了 gem 'pg'？
'pg' 添加，Gemfile: gem 'pg', group: :production gem 'sqlite3', group: :development
我猜还是不行？
是的。上面又发现了一条红线。 /home/deploy/inscope/tmp/build-142737353426931/vendor/bundle/ruby/2.2.0/gems/activesupport-4.1.0/lib/active_support/values/time_zone.rb:285: warning: circular argument reference - now
您在使用指南针吗？如果是，这是不久前的issue。他们现在就修好了。否则，请尝试将您的 Rails 版本更新到至少 4.1.9。

标签： ruby-on-rails ruby database postgresql deployment

【解决方案1】：

你必须添加

gem 'pg'

在您的GEMFILE 中，您可以在第一行错误中看到它：

    Gem::LoadError: Specified 'postgresql' for database adapter, 
but the gem is not loaded.
 Add `gem 'pg'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord).

【讨论】：