多个 Rails 个项目，每个项目具有不同的数据库
Multiple Rails projects with different databases for each
我是 Rails 的新手，在完成 Heroku 教程后，我使用 PostgresQL 设置了一个项目。
一位朋友也在学习 Rails 遵循了一个不同的教程，该教程使用 SQLite 作为数据库，我已经克隆了它。
当使用 SQLite 项目启动 rails 服务器时，我不断收到错误提示该项目正在尝试使用 PostgresQL 并告诉我将 gem pg 添加到我的 Gemfile。
我似乎只能在网上找到各种关于从 MySQL/SQLite/etc 迁移到 PostgresQL 的帖子，但我不想迁移。
我的database.yml如下：
# SQLite version 3.x
# gem install sqlite3
#
# Ensure the SQLite 3 gem is defined in your Gemfile
# gem 'sqlite3'
#
default: &default
adapter: sqlite3
pool: 5
timeout: 5000
development:
<<: *default
database: db/development.sqlite3
# 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: db/test.sqlite3
production:
<<: *default
database: db/production.sqlite3
RubyMine报错是：
/usr/bin/ruby -e $stdout.sync=true;$stderr.sync=true;load([=12=]=ARGV.shift) /Users/Ty/Rails/TSCLunch/web/bin/rails server -b 0.0.0.0 -p 3000 -e development
=> Booting WEBrick
=> Rails 4.2.0 application starting in development on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
Exiting
/Users/Ty/.gem/ruby/2.0.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/connection_specification.rb:177:in `rescue in spec': 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)
from /Users/Ty/.gem/ruby/2.0.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/connection_specification.rb:174:in `spec'
from /Users/Ty/.gem/ruby/2.0.0/gems/activerecord-4.2.0/lib/active_record/connection_handling.rb:50:in `establish_connection'
from /Users/Ty/.gem/ruby/2.0.0/gems/activerecord-4.2.0/lib/active_record/railtie.rb:120:in `block (2 levels) in <class:Railtie>'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/lazy_load_hooks.rb:28:in `block in on_load'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/lazy_load_hooks.rb:27:in `each'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/lazy_load_hooks.rb:27:in `on_load'
from /Users/Ty/.gem/ruby/2.0.0/gems/activerecord-4.2.0/lib/active_record/railtie.rb:116:in `block in <class:Railtie>'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/initializable.rb:30:in `instance_exec'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/initializable.rb:30:in `run'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/initializable.rb:55:in `block in run_initializers'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:150:in `block in tsort_each'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:183:in `block (2 levels) in each_strongly_connected_component'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:219:in `each_strongly_connected_component_from'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:182:in `block in each_strongly_connected_component'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:180:in `each'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:180:in `each_strongly_connected_component'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:148:in `tsort_each'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/initializable.rb:54:in `run_initializers'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/application.rb:352:in `initialize!'
from /Users/Ty/Rails/TSCLunch/web/config/environment.rb:5:in `<top (required)>'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `require'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `block in require'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:240:in `load_dependency'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `require'
from /Users/Ty/Rails/TSCLunch/web/config.ru:3:in `block in <main>'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/builder.rb:55:in `instance_eval'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/builder.rb:55:in `initialize'
from /Users/Ty/Rails/TSCLunch/web/config.ru:in `new'
from /Users/Ty/Rails/TSCLunch/web/config.ru:in `<main>'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/builder.rb:49:in `eval'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/builder.rb:49:in `new_from_string'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/builder.rb:40:in `parse_file'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/server.rb:299:in `build_app_and_options_from_config'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/server.rb:208:in `app'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/server.rb:61:in `app'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/server.rb:336:in `wrapped_app'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/server.rb:139:in `log_to_stdout'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/server.rb:78:in `start'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:80:in `block in server'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:75:in `tap'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:75:in `server'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands.rb:17:in `<top (required)>'
from /Users/Ty/Rails/TSCLunch/web/bin/rails:4:in `require'
from /Users/Ty/Rails/TSCLunch/web/bin/rails:4:in `<top (required)>'
from -e:1:in `load'
from -e:1:in `<main>'
Process finished with exit code 1
您可以通过两种方式为 ActiveRecord 指定适配器。
- 使用
ENV['DATABASE_URL'] 环境变量
- 使用
database.yml配置文件
如果您同时设置了 config/database.yml 和 ENV['DATABASE_URL']，那么 Rails 会将配置合并在一起。我认为这就是导致您出现问题的原因。
如果是这样，您可以删除环境变量或在 database.yml
中明确指定 url
我鼓励您阅读以下文章以获取更多信息：http://guides.rubyonrails.org/configuring.html#configuring-a-database
我假设您只想在本地获得一个 'works' 而不是在 heroku 上的项目，无论它使用的是 Postgres 还是 SQLITE3，是吗？
你能post 一份你的 Gemfile 的副本吗？由于您遵循了 Heroku 教程，因此从您的 post 中不清楚您遵循了哪些其他步骤，除了您可能通过 运行 在命令行上执行以下操作创建了您的应用程序：
$> rails new myapp --database=postgresql
这会将 "gem 'pg'" 添加到您的 Gemfile 中，并且会为其创建一个合适的 database.yml。但是如果你复制了另一个 database.yml 指定 SQLITE3，现在你的 Rails 环境很混乱。
如果您的 Gemfile 中确实有 'gem pg'，请尝试以下步骤：
1) 在您的 Gemfile 中，删除 'pg' 行并将其替换为：
gem'sqlite3'
2) 做一个 'bundle install' 来安装 SQLITE3，你的克隆 database.yml 无论如何指定。
3) 运行 以下命令重置您的数据库：
$> 耙子 db:reset
希望这会让你重新开始。现在你应该有一个使用 SQLITE3 而不是 Postgres 的项目。您将无法将它部署到 Heroku，因为它们不允许将 SQLITE3 用于生产环境。
如果你让它在本地与 SQLITE3 一起工作，然后想部署到 Heroku，他们提供了一个从 SQLITE3 返回到 Postgres 的简单过程：https://devcenter.heroku.com/articles/sqlite3
我是 Rails 的新手，在完成 Heroku 教程后，我使用 PostgresQL 设置了一个项目。
一位朋友也在学习 Rails 遵循了一个不同的教程，该教程使用 SQLite 作为数据库，我已经克隆了它。
当使用 SQLite 项目启动 rails 服务器时，我不断收到错误提示该项目正在尝试使用 PostgresQL 并告诉我将 gem pg 添加到我的 Gemfile。
我似乎只能在网上找到各种关于从 MySQL/SQLite/etc 迁移到 PostgresQL 的帖子，但我不想迁移。
我的database.yml如下：
# SQLite version 3.x
# gem install sqlite3
#
# Ensure the SQLite 3 gem is defined in your Gemfile
# gem 'sqlite3'
#
default: &default
adapter: sqlite3
pool: 5
timeout: 5000
development:
<<: *default
database: db/development.sqlite3
# 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: db/test.sqlite3
production:
<<: *default
database: db/production.sqlite3
RubyMine报错是：
/usr/bin/ruby -e $stdout.sync=true;$stderr.sync=true;load([=12=]=ARGV.shift) /Users/Ty/Rails/TSCLunch/web/bin/rails server -b 0.0.0.0 -p 3000 -e development
=> Booting WEBrick
=> Rails 4.2.0 application starting in development on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
Exiting
/Users/Ty/.gem/ruby/2.0.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/connection_specification.rb:177:in `rescue in spec': 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)
from /Users/Ty/.gem/ruby/2.0.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/connection_specification.rb:174:in `spec'
from /Users/Ty/.gem/ruby/2.0.0/gems/activerecord-4.2.0/lib/active_record/connection_handling.rb:50:in `establish_connection'
from /Users/Ty/.gem/ruby/2.0.0/gems/activerecord-4.2.0/lib/active_record/railtie.rb:120:in `block (2 levels) in <class:Railtie>'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/lazy_load_hooks.rb:38:in `instance_eval'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/lazy_load_hooks.rb:38:in `execute_hook'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/lazy_load_hooks.rb:28:in `block in on_load'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/lazy_load_hooks.rb:27:in `each'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/lazy_load_hooks.rb:27:in `on_load'
from /Users/Ty/.gem/ruby/2.0.0/gems/activerecord-4.2.0/lib/active_record/railtie.rb:116:in `block in <class:Railtie>'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/initializable.rb:30:in `instance_exec'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/initializable.rb:30:in `run'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/initializable.rb:55:in `block in run_initializers'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:150:in `block in tsort_each'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:183:in `block (2 levels) in each_strongly_connected_component'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:219:in `each_strongly_connected_component_from'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:182:in `block in each_strongly_connected_component'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:180:in `each'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:180:in `each_strongly_connected_component'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:148:in `tsort_each'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/initializable.rb:54:in `run_initializers'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/application.rb:352:in `initialize!'
from /Users/Ty/Rails/TSCLunch/web/config/environment.rb:5:in `<top (required)>'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `require'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `block in require'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:240:in `load_dependency'
from /Users/Ty/.gem/ruby/2.0.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `require'
from /Users/Ty/Rails/TSCLunch/web/config.ru:3:in `block in <main>'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/builder.rb:55:in `instance_eval'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/builder.rb:55:in `initialize'
from /Users/Ty/Rails/TSCLunch/web/config.ru:in `new'
from /Users/Ty/Rails/TSCLunch/web/config.ru:in `<main>'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/builder.rb:49:in `eval'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/builder.rb:49:in `new_from_string'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/builder.rb:40:in `parse_file'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/server.rb:299:in `build_app_and_options_from_config'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/server.rb:208:in `app'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/server.rb:61:in `app'
from /Users/Ty/.gem/ruby/2.0.0/gems/rack-1.6.0/lib/rack/server.rb:336:in `wrapped_app'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/server.rb:139:in `log_to_stdout'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/server.rb:78:in `start'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:80:in `block in server'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:75:in `tap'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:75:in `server'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
from /Users/Ty/.gem/ruby/2.0.0/gems/railties-4.2.0/lib/rails/commands.rb:17:in `<top (required)>'
from /Users/Ty/Rails/TSCLunch/web/bin/rails:4:in `require'
from /Users/Ty/Rails/TSCLunch/web/bin/rails:4:in `<top (required)>'
from -e:1:in `load'
from -e:1:in `<main>'
Process finished with exit code 1
您可以通过两种方式为 ActiveRecord 指定适配器。
- 使用
ENV['DATABASE_URL']环境变量 - 使用
database.yml配置文件
如果您同时设置了 config/database.yml 和 ENV['DATABASE_URL']，那么 Rails 会将配置合并在一起。我认为这就是导致您出现问题的原因。
如果是这样，您可以删除环境变量或在 database.yml
我鼓励您阅读以下文章以获取更多信息：http://guides.rubyonrails.org/configuring.html#configuring-a-database
我假设您只想在本地获得一个 'works' 而不是在 heroku 上的项目，无论它使用的是 Postgres 还是 SQLITE3，是吗？
你能post 一份你的 Gemfile 的副本吗？由于您遵循了 Heroku 教程，因此从您的 post 中不清楚您遵循了哪些其他步骤，除了您可能通过 运行 在命令行上执行以下操作创建了您的应用程序：
$> rails new myapp --database=postgresql
这会将 "gem 'pg'" 添加到您的 Gemfile 中，并且会为其创建一个合适的 database.yml。但是如果你复制了另一个 database.yml 指定 SQLITE3，现在你的 Rails 环境很混乱。
如果您的 Gemfile 中确实有 'gem pg'，请尝试以下步骤：
1) 在您的 Gemfile 中，删除 'pg' 行并将其替换为： gem'sqlite3'
2) 做一个 'bundle install' 来安装 SQLITE3，你的克隆 database.yml 无论如何指定。
3) 运行 以下命令重置您的数据库： $> 耙子 db:reset
希望这会让你重新开始。现在你应该有一个使用 SQLITE3 而不是 Postgres 的项目。您将无法将它部署到 Heroku，因为它们不允许将 SQLITE3 用于生产环境。
如果你让它在本地与 SQLITE3 一起工作，然后想部署到 Heroku，他们提供了一个从 SQLITE3 返回到 Postgres 的简单过程：https://devcenter.heroku.com/articles/sqlite3