Heroku 和 Rails：Postgres 的 Gem 加载错误，但它在 GEMFILE 中指定答案

【问题标题】：Heroku and Rails: Gem Load Error with Postgres, however it is Specified in GEMFILEHeroku 和 Rails：Postgres 的 Gem 加载错误，但它在 GEMFILE 中指定
【发布时间】：2017-01-08 18:36:27
【问题描述】：

所以我正在尝试将一个小项目部署到 Heroku，但是当我部署它并尝试运行 heroku run rake db:migrate 时，它返回了以下错误：

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).
/app/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/connection_specification.rb:177:in `rescue in spec'
/app/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/connection_specification.rb:174:in `spec'
/app/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.6/lib/active_record/connection_handling.rb:50:in `establish_connection'
/app/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.6/lib/active_record/railtie.rb:120:in `block (2 levels) in <class:Railtie>'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/lazy_load_hooks.rb:28:in `block in on_load'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/lazy_load_hooks.rb:27:in `each'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/lazy_load_hooks.rb:27:in `on_load'
/app/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.6/lib/active_record/railtie.rb:116:in `block in <class:Railtie>'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/initializable.rb:30:in `instance_exec'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/initializable.rb:30:in `run'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/initializable.rb:55:in `block in run_initializers'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/initializable.rb:54:in `run_initializers'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/application.rb:352:in `initialize!'
/app/config/environment.rb:5:in `<top (required)>'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `block in require'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240:in `load_dependency'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/application.rb:328:in `require_environment!'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/application.rb:457:in `block in run_tasks_blocks'
Gem::LoadError: pg is not part of the bundle. Add it to Gemfile.
/app/vendor/bundle/ruby/2.2.0/gems/bundler-1.11.2/lib/bundler/rubygems_integration.rb:304:in `block in replace_gem'
/app/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/postgresql_adapter.rb:16:in `<top (required)>'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `block in require'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240:in `load_dependency'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
/app/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.6/lib/active_record/connection_adapters/connection_specification.rb:175:in `spec'
/app/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.6/lib/active_record/connection_handling.rb:50:in `establish_connection'
/app/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.6/lib/active_record/railtie.rb:120:in `block (2 levels) in <class:Railtie>'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/lazy_load_hooks.rb:28:in `block in on_load'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/lazy_load_hooks.rb:27:in `each'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/lazy_load_hooks.rb:27:in `on_load'
/app/vendor/bundle/ruby/2.2.0/gems/activerecord-4.2.6/lib/active_record/railtie.rb:116:in `block in <class:Railtie>'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/initializable.rb:30:in `instance_exec'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/initializable.rb:30:in `run'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/initializable.rb:55:in `block in run_initializers'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/initializable.rb:54:in `run_initializers'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/application.rb:352:in `initialize!'
/app/config/environment.rb:5:in `<top (required)>'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `block in require'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240:in `load_dependency'
/app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in `require'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/application.rb:328:in `require_environment!'
/app/vendor/bundle/ruby/2.2.0/gems/railties-4.2.6/lib/rails/application.rb:457:in `block in run_tasks_blocks'
Tasks: TOP => db:migrate => environment
(See full trace by running task with --trace)

我可以从第一行看到我需要在我的 gem 文件中加载 pg gem，但是我已经将它加载到生产组中并通过 bundle 安装。这是我的GEMFILE：

source 'https://rubygems.org'
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.2.6'
gem 'sass-rails', '~> 5.0'
gem 'uglifier', '>= 1.3.0'
gem 'coffee-rails', '~> 4.1.0'
gem 'jquery-rails'
gem 'turbolinks'
gem 'jbuilder', '~> 2.0'
gem 'sdoc', '~> 0.4.0', group: :doc
gem 'devise', '~> 3.5', '>= 3.5.6'
gem 'paperclip', '~> 4.3', '>= 4.3.6'
gem 'materialize-sass'
gem "font-awesome-rails"
gem 'bootstrap-sass', '~> 3.2.0'
gem 'autoprefixer-rails'
gem 'ratyrate'

group :development, :test do
    gem 'byebug'
end

group :development do
  gem 'web-console', '~> 2.0'
  gem 'spring'
end

group :development do
  gem 'sqlite3'
end

group :production do
  gem 'pg'
  gem 'rails_12factor'
end

在发布此问题之前，我已使用那里的答案阅读了同一问题（rake about database adapter inconsistent with database.yml、rake aborted! Gem::LoadError: Specified 'postgresql' for database adapter、Gem::LoadError: Specified 'postgresql' for database adapter, but the gem is not loaded）的答案，但错误仍然存在。

感谢您的帮助:)

【问题讨论】：

捆绑后你是否将 gemlock 文件推送到 heroku？
是的，Gemfile.lock 文件在存储库中
尝试在生产环境之外编写 pg，捆绑，使用 gemlock、gemfile 提交你的代码，然后将代码推送到 heroku，然后再试一次
是的！这是解决方案，谢谢！
我写它作为答案希望你能投票

标签： ruby-on-rails ruby postgresql heroku

【解决方案1】：

也应该通过升级 rails >= 5.1.5 来修复

https://github.com/rails/rails/issues/31673

【讨论】：

【解决方案2】：

我遇到了这个确切的问题，并通过更改为：

'pg', '~> 0.20'

【讨论】：

如果在堆栈转储中您可以看到较低版本的 pg 并推送到 Heroku（至少），则可以这样做
同样的问题，我们使用的是 PG 1.0.0 - 切换到 0.2 有效。没有理由对我们来说显而易见。

【解决方案3】：

尝试在生产之外编写 pg，捆绑，使用 gemlock、gemfile 提交你的代码并将代码推送到 heroku，然后再试一次

【讨论】：