Heroku with rails 5 error Gem::LoadError: 为数据库适配器指定了“postgresql"

我是一名 Rails 初学者，在部署到 Heroku 时遇到了一些问题.

I am a Rails beginner and i see some issue while deploying to Heroku.

之前我使用 SQLite3，后来当我知道我需要 postgresql 时，我安装了相同的并且在本地机器上工作.

Earlier i used SQLite3, later when i understood that i needed postgresql i installed the same and work on local machine.

从 sqlite 迁移到 postgresql 后，一次部署顺利.现在我看到了一些问题.

One deployment went fine after migrating from sqlite to postgresql. Now i see some issue.

Heroku 日志、Gem 文件和 Database.yml 详细信息如下.

Heroku logs, Gem file and Database.yml details are as below.

有人可以帮助我吗.

提前谢谢...!!!

Gem 文件的一部分:

Part of Gem file:

group :development, :test do
    gem 'pg', '~> 1.0.0'
  gem 'rails_12factor'
  #gem 'sqlite3'
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
  # Adds support for Capybara system testing and selenium driver
  gem 'capybara', '~> 2.13'
  gem 'selenium-webdriver'
end

group :production do
    gem 'pg', '~> 1.0.0'
  gem 'rails_12factor'
end

group :development do
  # Access an IRB console on exception pages or by using <%= console %> anywhere in the code.
  gem 'web-console', '>= 3.3.0'
end

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

数据库.yml:

development:
    adapter: postgresql
    encoding: unicode
    database: database_postgresql
    pool: 5
    username: postgres
    password: secret

test:
   adapter: postgresql
    encoding: unicode
    database: database_postgresql_test
    pool: 5
    username: postgres
    password: secret

production:
   adapter: postgresql
    encoding: unicode
    database: database_postgresql
    pool: 5
    username: postgres
    password: secret

Heroku 日志的一部分.

Part of Heroku logs.

remote: -----> Installing node-v6.11.1-linux-x64
remote: -----> Detecting rake tasks
remote: -----> Preparing app for Rails asset pipeline
remote:        Running: rake assets:precompile
remote:        Yarn executable was not detected in the system.
remote:        Download Yarn at https://yarnpkg.com/en/docs/install
remote:        I, [2018-01-15T13:38:08.180450 #590]  INFO -- : Writing /tmp/build_3dd0bceef080f0d8f6be5bc51b9d4a48/public/assets/jumbotron--032aba6cd1415006731040523573e7138c703aedc6d1f46b3622cbe4c9feec27.jpg
remote:        rake aborted!
remote:        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).
remote:        /tmp/build_3dd0bceef080f0d8f6be5bc51b9d4a48/vendor/bundle/ruby/2.3.0/gems/activerecord-5.1.4/lib/active_record/connection_adapters/connection_specification.rb:188:in `rescue in spec'

remote:        /tmp/build_3dd0bceef080f0d8f6be5bc51b9d4a48/vendor/bundle/ruby/2.3.0/gems/sprockets-rails-3.2.1/lib/sprockets/rails/task.rb:67:in `block (2 levels) in define'
remote:        /tmp/build_3dd0bceef080f0d8f6be5bc51b9d4a48/vendor/bundle/ruby/2.3.0/gems/rake-12.3.0/exe/rake:27:in `<top (required)>'
remote:        Tasks: TOP => assets:precompile
remote:        (See full trace by running task with --trace)
remote:  !
remote:  !     Precompiling assets failed.
remote:  !
remote:  !     Push rejected, failed to compile Ruby app.
remote:
remote:  !     Push failed
remote: Verifying deploy...
remote:
remote: !       Push rejected to damp-beyond-28813.