Rails中的多个数据库连接

Question

我正在使用active_delegate在Rails中进行多个连接。 这里我使用mysql作为master_database用于某些模型，而postgresql用于其他一些模型。

问题是，当我尝试访问mysql模型时，我收到以下错误！ 堆栈跟踪显示，它仍然使用postgresql适配器来访问我的mysql模型！

RuntimeError: ERROR C42P01  Mrelation "categories" does not exist   P15 F.\src\backend\parser\parse_relation.c  L886    RparserOpenTable: SELECT * FROM "categories" 

STACKTRACE
===========
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/abstract_adapter.rb:212:in `log'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/postgresql_adapter.rb:507:in `execute'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/postgresql_adapter.rb:985:in `select_raw'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/postgresql_adapter.rb:972:in `select'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `select_all_without_query_cache'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/abstract/query_cache.rb:60:in `select_all'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/abstract/query_cache.rb:81:in `cache_sql'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/connection_adapters/abstract/query_cache.rb:60:in `select_all'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/base.rb:661:in `find_by_sql'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/base.rb:1553:in `find_every'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/active_record/base.rb:615:in `find'
D:/ROR/Aptana/dedomenon/app/models/category.rb:50:in `get_all_with_exclusive_scope'
D:/ROR/Aptana/dedomenon/app/models/category.rb:50:in `get_all_with_exclusive_scope'
D:/ROR/Aptana/dedomenon/app/controllers/categories_controller.rb:48:in `index'

这是我的database.yml文件

postgre: &postgre
  adapter: postgresql
  database: codex
  host: localhost
  username: postgres
  password: root
  port: 5432  

mysql: &mysql
  adapter: mysql
  database: project
  host: localhost
  username: root
  password: root
  port: 3306  

development:
  <<: *postgre

test:
  <<: *postgre

production:
  <<: *postgre

master_database:
  <<: *mysql

我的master_database模型是这样的

class Category < ActiveRecord::Base

  delegates_connection_to :master_database, :on => [:create, :save, :destroy]

end

有人有任何解决方案？

Answer 1

其他方式：

class Abc < ActiveRecord::Base
  establish_connection Rails.configuration.database_configuration["test"]
end

Answer 2

现在可能想看看https://github.com/tchandy/octopus 。

Answer 3

这将更改单个模型对象的数据库连接。

$config = YAML.load_file(File.join(File.dirname(__FILE__),
   '../config/database.yml'))

class ModelWithDifferentConnection < ActiveRecord::Base
  establish_connection $config['connection_name_from_database_yml']
end

如果您使用相同的服务器但只使用不同的数据库文件，那么您可以执行类似的操作。

class ModelWithDifferentConnection < ActiveRecord::Base

  # Lives in the CURRICULUM database
  def self.table_name
    "database.table"
  end

end

Answer 4

我强烈建议使用MySQL适配器的MyReplication插件，它可以帮助您以优雅的方式在运行时切换连接：

User.using(:another_database) do
  u = User.all
end

https://github.com/minhnghivn/my_replication

Answer 5

我试过你的Sample，仍然收到错误!!

superclass mismatch for class MysqlAdapter

我想，问题出在我的database.yml文件中。请检查此文件

database_mysql: 
  adapter: mysql
  database: project
  host: localhost
  username: root
  password: root
  port: 3306  

development:
  adapter: postgresql
  database: codex
  host: localhost
  username: postgres
  password: root
  port: 5432  

test:
  adapter: postgresql
  database: codex
  host: localhost
  username: postgres
  password: root
  port: 5432  

production:
  adapter: postgresql
  database: codex
  host: localhost
  username: postgres
  password: root
  port: 5432  

我只在开发模式下启动杂种。

这是我的模型超类

$config = YAML.load_file(File.join(File.dirname(__FILE__),
   '../../config/database.yml'))

class MasterDatabase < ActiveRecord::Base
    self.abstract_class = true
    establish_connection $config['database_mysql']    
end 

请纠正我..

Answer 6

我还必须连接并管理两个不同的数据库，所以我创建了一个名为secondbase的gem： http ：//github.com/karledurante/secondbase

Answer 7

我不知道active_delegate，但我最近不得不访问工作应用程序的不同数据库，并没有什么真正适合我想要的。 所以我为自己写了一些东西，它就像我们说的那样在生产应用程序中运行。

固定链接connection_ninja