相关疑难解决方法(0)

我试图在Heroku 上使用带Ruby on Rails的postgresql但是出错了

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). (Gem::LoadError)

请帮我解决这个问题.

我是Rails的新手.此应用程序在我的本地计算机上正常工作,并且没有任何问题地部署.但是当我跑步时heroku run rake db:migrate,我收到了这个错误:

Running `rake db:migrate` attached to terminal... up, run.1269
rake aborted!
Gem::LoadError: Specified 'postgresql' for database adapter, but the gem is not loaded. Add `gem 'pg'` to your Gemfile.

在database.yml(rails生成的默认文件)中:

default: &default
    adapter: sqlite3
    pool: 5
    timeout: 5000

development:
  <<: *default
  database: db/development.sqlite3

test:
  <<: *default
  database: db/test.sqlite3

production:
  <<: *default
  database: db/production.sqlite3

运行时rake about,我有这个错误:

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).

如果我添加pggem,则rake about提供此输出:

About your application's environment
Ruby version              2.1.0-p0 (x86_64-darwin13.0)
RubyGems version          2.2.2
Rack version              1.5
Rails …