ActiveRecord :: AdapterNotSpecified数据库配置未指定适配器

Question

当我使用heroku打开我的网络应用程序工作正常但是当我使用rails s（localhost）时，我遇到了这个错误：

ActiveRecord::AdapterNotSpecified database configuration does not specify adapter

这是为什么？

这是我的database.yml

# 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

这是我的宝石文件：

source 'https://rubygems.org'


gem 'pg'

gem 'bootstrap-sass', '~> 3.1.1'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.0.3'

# Use SCSS for stylesheets
gem 'sass-rails', '~> 4.0.0'

# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'

# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '~> 4.0.0'

# See https://github.com/sstephenson/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', '~> 1.2'

group :doc do
  # bundle exec rake doc:rails generates the API under doc/api.
  gem 'sdoc', require: false
end

group :production do
  gem 'rails_12factor', '0.0.2'
end

# Use ActiveModel has_secure_password
# gem 'bcrypt-ruby', '~> 3.1.2'

# Use unicorn as the app server
# gem 'unicorn'

# Use Capistrano for deployment
# gem 'capistrano', group: :development

# Use debugger
# gem 'debugger', group: [:development, :test]

Answer 1

要让您的应用在本地工作，您需要：

1. Install Postgresql在您的计算机上
2. Create a database了解您的发展需求（让我们称之为my_app_development）

3. 将您的database.yml更改为：

   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: my_app_development
   

4. 运行rake db:migrate

Answer 2

您没有显示导致此查询的命令，但如果您传递字符串而不是符号，则可能会发生这种情况。

例如：

irb(main):001:0> ActiveRecord::Base.establish_connection("#{Rails.env}")
ActiveRecord::AdapterNotSpecified: database configuration does not specify adapter

但是如果你使用符号，那就可以了。

irb(main):001:0> ActiveRecord::Base.establish_connection("#{Rails.env}".to_sym)
=> #<ActiveRecord::ConnectionAdapters::ConnectionPool:0x007f2f484a32a0 #....

Answer 3

您的database.yml应如下所示：

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
  username: my_username
  password: my_password

development:
  <<: *default
  database: "development_database_name"

test:
  <<: *default
  database: "test_database_name"

production:
  <<: *default
  database: "production_database_name"

将development_database_name编辑为本地数据库名称。 同时将my_username和my_password编辑为正确的db用户名和密码。

Answer 4

不再删除标签，完美标识，例如：

# 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: utf8
  pool: 5
  host: 192.168.0.121
  username: postgres
  password: passpostgres

development:
  <<: *default
  database: DBPOSTGRES
 # 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: DBPOSTGRES
# 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: DBPOSTGRES
  password: <%= ENV['passpostgres'] %>

Answer 5

为什么在database.yml中使用yml node reference？

你应该有这样的东西：

#config/database.yml
development:
  adapter: mysql2
  encoding: utf8
  database: ****
  pool: 5
  username: ****
  password: ****
  host: ***.***.***.*** #-> only for third party db server

production:
  adapter: postgresql
  encoding: utf8
  database: ****
  pool: 5
  username: ****
  password: ****
  host: ***.***.***.*** #-> only for third party db server

---

<强>更新

Rails使用数据库运行。您已连接到数据库以使其正常工作，为此，您必须在database.yml

中定义不同的连接详细信息

要定义正确的信息，您需要了解Rails在多个environments - development＆amp; production是最常用的两个

要使Rails在本地（开发）环境中运行，您需要定义正确的数据库详细信息。这意味着您需要一个数据库才能连接 - 通常是setting up a local mysql / pgsql server

底线是您使用以下方式连接到数据库：

  

  
• 主机名
  
• 用户名
  
• 密码
  
• db name
  

您需要在config/database.yml文件

中定义这些内容

如果您的服务器在本地环境中运行，则您的database.yml文件将如下所示：

#config/database.yml
development:
  adapter: mysql2
  encoding: utf8
  database: db_name
  pool: 5
  username: username
  password: password

Answer 6

如果您尝试使用无轨的activerecord，则可能会在具有多个环境设置的database.yml中遇到此问题。因此，您需要像这样将环境密钥传递到配置设置中：

DB_ENV ||= 'development'
connection_details = YAML::load(File.open('config/database.yml'))
ActiveRecord::Base.establish_connection(connection_details[DB_ENV])

Answer 7

在我的情况下，原因在我的Rakefile中。

当我运行rake db:migrate时，我得到了：

rake db:migrate
rake aborted!
ActiveRecord::AdapterNotSpecified: The `default_env` database is not configured for the `default_env` environment.

Available databases configurations are:

development
test
production

我已经在我的 Rakefile 中找到了该行：

ActiveRecord::Base.establish_connection(ENV['DATABASE_URL'])

并更改为默认值： ActiveRecord::Base.establish_connection(ENV['DATABASE_URL'] || 'postgres://localhost/db_name')

，现在工作正常。您可以找到here

的详细信息