Rails 4：将数据库更改为 postgresql（来自 sqlite3）

【问题标题】：Rails 4: changing database to postgresql (from sqlite3)Rails 4：将数据库更改为 postgresql（来自 sqlite3）
【发布时间】：2016-06-11 16:10:52
【问题描述】：

所以我想将我的数据库表单 sqlite3 更改为 pg。我尝试遵循this 指南。有一些关于数据库密码的东西，我不知道我应该把那个密码放在哪里。有没有默认的？

宝石文件

source 'https://rubygems.org'

gem 'rails', '4.2.5.1'
gem 'pg'
gem 'sass-rails', '~> 5.0'
gem 'uglifier', '>= 1.3.0'
gem 'coffee-rails', '~> 4.1.0'
gem 'decent_exposure'
gem 'slim'
gem 'nprogress-rails'
gem 'jquery-rails'
gem 'turbolinks'
gem 'jbuilder', '~> 2.0'
gem 'sdoc', '~> 0.4.0', group: :doc
gem 'ffaker'

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

group :development do
  gem 'pry-rails'
  gem 'better_errors'
  gem 'binding_of_caller'
  gem 'spring'
  # gem 'sqlite3'
end

数据库.yml

default: &default
  adapter: postgresql
  host: localhost
  encoding: unicode
  pool: 5

development:
  <<: *default
  database: blog_development

test:
  <<: *default
  database: blog_test

production:
  <<: *default
  database: blog_production

捆绑安装结果是 100% 成功。

当我尝试创建数据库时：

bin/rake db:create
Running via Spring preloader in process 12795
could not connect to server: No such file or directory
    Is the server running locally and accepting
    connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `initialize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `new'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `connect'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:242:in `initialize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `new'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `postgresql_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:438:in `new_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:448:in `checkout_new_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:422:in `acquire_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:349:in `block in checkout'
/home/dominik/.rvm/rubies/ruby-2.2.4/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:348:in `checkout'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:263:in `block in connection'
/home/dominik/.rvm/rubies/ruby-2.2.4/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:262:in `connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:571:in `retrieve_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_handling.rb:113:in `retrieve_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_handling.rb:87:in `connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/postgresql_database_tasks.rb:6:in `connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/postgresql_database_tasks.rb:15:in `create'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:93:in `create'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:107:in `block in create_current'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:275:in `block in each_current_configuration'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:274:in `each'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:274:in `each_current_configuration'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:106:in `create_current'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/railties/databases.rake:17:in `block (2 levels) in <top (required)>'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:240:in `call'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:240:in `block in execute'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:235:in `each'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:235:in `execute'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:179:in `block in invoke_with_call_chain'
/home/dominik/.rvm/rubies/ruby-2.2.4/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:172:in `invoke_with_call_chain'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/task.rb:165:in `invoke'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:150:in `invoke_task'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:106:in `block (2 levels) in top_level'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:106:in `each'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:106:in `block in top_level'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:115:in `run_with_threads'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:100:in `top_level'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:78:in `block in run'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:176:in `standard_exception_handling'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/rake-10.5.0/lib/rake/application.rb:75:in `run'
/home/dominik/github/dd_blog/bin/rake:9:in `<top (required)>'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:268:in `load'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:268:in `block in load'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:240:in `load_dependency'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activesupport-4.2.5.1/lib/active_support/dependencies.rb:268:in `load'
/home/dominik/.rvm/rubies/ruby-2.2.4/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/home/dominik/.rvm/rubies/ruby-2.2.4/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
-e:1:in `<main>'
Couldn't create database for {"adapter"=>"postgresql", "encoding"=>"unicode", "pool"=>5, "database"=>"blog_development"}

rake db:迁移

rake aborted!
PG::ConnectionBad: could not connect to server: Connection refused
    Is the server running on host "localhost" (127.0.0.1) and accepting
    TCP/IP connections on port 5432?
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `initialize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `new'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `connect'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:242:in `initialize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `new'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `postgresql_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:438:in `new_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:448:in `checkout_new_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:422:in `acquire_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:349:in `block in checkout'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:348:in `checkout'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:263:in `block in connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:262:in `connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:571:in `retrieve_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_handling.rb:113:in `retrieve_connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/connection_handling.rb:87:in `connection'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/migration.rb:916:in `initialize'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/migration.rb:823:in `new'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/migration.rb:823:in `up'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/migration.rb:801:in `migrate'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/tasks/database_tasks.rb:137:in `migrate'
/home/dominik/.rvm/gems/ruby-2.2.4/gems/activerecord-4.2.5.1/lib/active_record/railties/databases.rake:44:in `block (2 levels) in <top (required)>'
/home/dominik/.rvm/gems/ruby-2.2.4/bin/ruby_executable_hooks:15:in `eval'
/home/dominik/.rvm/gems/ruby-2.2.4/bin/ruby_executable_hooks:15:in `<main>'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

请注意，我之前从未使用过 postgres。也许需要一些配置？

附：我正在使用 Ubuntu 14.04

原来，我没有安装 postgresql。

【问题讨论】：

    标签： ruby-on-rails postgresql ruby-on-rails-4 sqlite


    【解决方案1】：

    有几件事，rake db:migrate 只会运行您的迁移，不会创建您的开发 deb。创建数据库的命令是： 耙分贝：创建

    您只能在创建数据库并连接到数据库后运行迁移。

    所以先尝试一下，如果失败，请检查以确保您正在运行 postgresql。我在 ubuntu 15.04 上，我将 postgres 作为服务运行，如果需要，我会考虑这样做。确认 postgresql 已正确安装并运行。在终端 'psql -V' 将返回您安装的 postgresql 版本。检查进程 $ ps aux | grep postgresl 。

    一旦您确认您已经启动并运行了 postgresql。接下来，从 database.yml 中删除 'host: localhost' 行，这不是必需的。接下来，在 database.yml 中尝试添加： port: 5432 在您的开发数据库下方。如果这仍然不能解决它下面的添加： host: ""

    【讨论】：

      【解决方案2】：

      1 - 将此添加到您的 Gemfile 中

      gem 'pg', '~> 0.15'

      2 - 将此添加到您的 database.yml 中，将 myapp 更改为您的应用程序名称

      # PostgreSQL. Versions 8.2 and up are supported.
#
# Install the pg driver:
#   gem install pg
# On OS X with Homebrew:
#   gem install pg -- --with-pg-config=/usr/local/bin/pg_config
# On OS X with MacPorts:
#   gem install pg -- --with-pg-config=/opt/local/lib/postgresql84/bin/pg_config
# On Windows:
#   gem install pg
#       Choose the win32 build.
#       Install PostgreSQL and put its /bin directory on your path.
#
# Configure Using Gemfile
# gem 'pg'
#
default: &default
  adapter: postgresql
  encoding: unicode
  # For details on connection pooling, see rails configuration guide
  # http://guides.rubyonrails.org/configuring.html#database-pooling
  pool: 5

development:
  <<: *default
  database: myapp_development

  # The specified database role being used to connect to postgres.
  # To create additional roles in postgres see `$ createuser --help`.
  # When left blank, postgres will use the default role. This is
  # the same name as the operating system user that initialized the database.
  #username: myapp

  # The password associated with the postgres role (username).
  #password:

  # Connect on a TCP socket. Omitted by default since the client uses a
  # domain socket that doesn't need configuration. Windows does not have
  # domain sockets, so uncomment these lines.
  #host: localhost

  # The TCP port the server listens on. Defaults to 5432.
  # If your server runs on a different port number, change accordingly.
  #port: 5432

  # Schema search path. The server defaults to $user,public
  #schema_search_path: myapp,sharedapp,public

  # Minimum log levels, in increasing order:
  #   debug5, debug4, debug3, debug2, debug1,
  #   log, notice, warning, error, fatal, and panic
  # Defaults to warning.
  #min_messages: notice

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: myapp_test

# As with config/secrets.yml, you never want to store sensitive information,
# like your database password, in your source code. If your source code is
# ever seen by anyone, they now have access to your database.
#
# Instead, provide the password as a unix environment variable when you boot
# the app. Read http://guides.rubyonrails.org/configuring.html#configuring-a-database
# for a full rundown on how to provide these environment variables in a
# production deployment.
#
# On Heroku and other platform providers, you may have a full connection URL
# available as an environment variable. For example:
#
#   DATABASE_URL="postgres://myuser:mypass@localhost/somedatabase"
#
# You can use this database configuration with:
#
#   production:
#     url: <%= ENV['DATABASE_URL'] %>
#
production:
  <<: *default
  database: myapp_production
  username: myapp
  password: <%= ENV['MYAPP_DATABASE_PASSWORD'] %>

      2 - 然后：

      rake db:purge
rake db:setup
rake db:migrate

      【讨论】：

        【解决方案3】：

        导轨 6+

        在 Rails 6.0 或更高版本中，您可以运行以下命令：

        rails db:system:change --to=postgresql

        它还接受mysql、sqlite3、oracle、sqlserver 和其他可以在this class 中看到的内容。

        【讨论】：

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