pg::error 错误关系用户已经存在

Question

我正在尝试将我的应用程序部署到 heroku。一切正常，直到我尝试运行“heroku run rake db:migrate”。然后我收到以下错误（请在新选项卡中打开此图像以更好地查看：

我在本地运行了 rake db:drop、rake db:create 和 rake db:migrate。然后我把它推到heroku并尝试再次运行“heroku run rake db:migrate”，但同样的错误。我知道这与已经有用户表的架构有关，但我没有在我的文件中看到它。

宝石文件：

source 'https://rubygems.org'


# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.2.6'
# Use sqlite3 as the database for Active Record

# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# See https://github.com/rails/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby

# Use jquery as the JavaScript library
gem 'jquery-rails'
# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.0'
# bundle exec rake doc:rails generates the API under doc/api.
gem 'sdoc', '~> 0.4.0', group: :doc
# for users
gem 'devise', '~> 4.2'
# Use ActiveModel has_secure_password
gem 'bcrypt', git: 'https://github.com/codahale/bcrypt-ruby.git', :require => 'bcrypt'
# Use Unicorn as the app server
# gem 'unicorn'
gem 'tzinfo-data'
# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug'
end

group :test do
  # for seeing test covarage
  gem 'simplecov', :require => false
end

group :development do
  # Access an IRB console on exception pages or by using <%= console %> in views
  gem 'web-console', '~> 2.0'
  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
  gem 'sqlite3'
end
# upload files
gem 'carrierwave', '~> 1.0'

# bootstraps
gem 'bootstrap-sass', '~> 3.3.4.1'
# Material Icons
gem 'material_icons'
# Material css
gem 'materialize-sass'

group :production do
    gem 'pg', '0.15'
    gem 'rails_12factor'
end

我还有其他事情要做还是我错过了什么？

Answer 1

这意味着您的表“用户”已经存在于 heroku 上。您真的要删除 heroku 上的所有表吗？如果是这样，你有你可以做的

heroku pg:reset DATABASE

https://devcenter.heroku.com/articles/heroku-postgresql#pg-reset

如果您只想对表进行一些更改，您应该真正使用迁移，例如

add_column :users, :my_attribute, ...
removeColumn :users, :my_attribute_to_remove

PS：在本地删除、创建、迁移数据库不会对 Heroku 上的数据库产生任何影响。