Question

rails，postgres，devise。有一个公司的边桌基地，对她来说我成功连接了。目标：创建一个模型User，它将与公司绑定，以使公司能够以用户身份登录。我决定通过has_one来制作比率。

user_corporation.rb：

class UserCorporation < ActiveRecord::Base
    belongs_to :user
    belongs_to :corporation
end

user.rb：

class User < ActiveRecord::Base

    devise :database_authenticatable,
            :rememberable,
            :trackable,
            :timeoutable,
            :authentication_keys => [:login]

    has_one :user_corporation
    has_one :corporation, :through => :user_corporation
end

corporation.rb：

class Corporation < OtherBaseconfiguration
    self.table_name = 'Corporations'
    has_one :user_corporation
    has_one :user, :through => :user_corporation
end

20160212185152_create_user_corporations.rb：

class CreateUserCorporations < ActiveRecord::Migration
  def change
    create_table :user_corporations do |t|
      t.belongs_to :user, index: true
      t.belongs_to :corporation, index: true
      t.timestamps null: false
    end
  end
end

rake db: migrate已执行，表已创建。在控制台中，尝试获取公司用户，我收到错误：

irb(main):006:0> @corpor.corporation
ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR:  relation "user_corporations" does not exist
LINE 5:                WHERE a.attrelid = '"user_corporations"'::reg...
                                          ^
:               SELECT a.attname, format_type(a.atttypid, a.atttypmod),
                     pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
                FROM pg_attribute a LEFT JOIN pg_attrdef d
                  ON a.attrelid = d.adrelid AND a.attnum = d.adnum
               WHERE a.attrelid = '"user_corporations"'::regclass
                 AND a.attnum > 0 AND NOT a.attisdropped
               ORDER BY a.attnum

    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql_adapter.rb:592:in `async_exec'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql_adapter.rb:592:in `block in exec_no_cache'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract_adapter.rb:472:in `block in log'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.5/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/abstract_adapter.rb:466:in `log'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql_adapter.rb:592:in `exec_no_cache'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql_adapter.rb:584:in `execute_and_clear'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql/database_statements.rb:160:in `exec_query'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql_adapter.rb:733:in `column_definitions'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/postgresql/schema_statements.rb:186:in `columns'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/schema_cache.rb:43:in `columns'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/schema_cache.rb:49:in `columns_hash'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/associations/association_scope.rb:85:in `column_for'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/associations/association_scope.rb:94:in `bind'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/associations/association_scope.rb:103:in `last_chain_scope'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activerecord-4.2.5/lib/active_record/associations/association_scope.rb:139:in `add_constraints'
... 13 levels...
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/railties-4.2.5/lib/rails/commands/console.rb:9:in `start'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:68:in `console'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/railties-4.2.5/lib/rails/commands.rb:17:in `<top (required)>'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `block in require'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:240:in `load_dependency'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require'
    from /home/marson/rails_project/infinity/bin/rails:9:in `<top (required)>'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:268:in `load'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:268:in `block in load'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:240:in `load_dependency'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/gems/2.2.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:268:in `load'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /home/marson/.rvm/rubies/ruby-2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'

我做错了什么？

Answer 1

也许我错过了它，但如果你只需要在公司和用户之间使用has_one到has_one，为什么要使用UserCorporations查找表呢？

Answer 2

您的设计存在缺陷，您尝试以错误的方式使用has_one并且失败了。您需要以下设计之一：的 A

公司有很多用户用户属于公司

（一个用户只属于一个公司，一个公司可以有很多用户）。

<强>乙

公司有很多UserCorporations 用户有很多UserCorporations UsedCorporation属于User UserCorporation属于公司

（这是多对多的，因此用户可以属于多个团队，而公司可能有多个用户）

<强> C

公司所属的用户用户有很多公司

（用户连接到多个团队，而Corp只能属于单个用户）

Answer 3

使用has_many :through执行此操作如（公司拥有许多用户belongs_to公司）

公司belongs_to用户用户has_many公司

（用户连接到多个公司，公司只能belong_to单个用户）

rails has_one through relation不存在

3 个答案: