從軌道中的兩個表中獲取數據？

我有兩個表emp和requisition從軌道中的兩個表中獲取數據？

emp.rb

class Emp < ActiveRecord::Base 

has_many :requisitions 


devise :database_authenticatable, :registerable, 
    :recoverable, :rememberable, :trackable, :validatable,:confirmable,:lockable 


    attr_accessor :email 

    attr_accessible :password,:password_confirmation,:remember_me, :email , :username 
    string_regex = /\A[a-z]+\z/i 
    validates :username, 
    :format => { :with => string_regex ,:message=> "must be string"}, 
     :uniqueness => { 
:case_sensitive => false 
} 
end

Requisition

class Requisition < ActiveRecord::Base 
belongs_to :emp 

attr_accessible :name , :unit , :quantity ,:from ,:particular ,:total , :cost 

validates :name , :unit , :quantity ,:from ,:particular ,:total , :cost , presence: true 

validates :particular, :presence => true, 
      :length => { :within => 6..60 } 

    validates :quantity, numericality: { only_integer: true }, 
      :length => {:maximum => 4} 

    validates :quantity, numericality: { only_integer: true }, 
      :length => {:maximum => 4} 

end

如果我要算EMP的徵用，我應該要做什麼編輯的數量？

在我的日誌

irb(main):002:0> @emp.requisitions.count 
(1.0ms) SELECT COUNT(*) FROM "requisitions" WHERE "requisitions"."emp_id" =$1 [[nil, 2]] 
PG::UndefinedColumn: ERROR: column requisitions.emp_id does not exist 
LINE 1: SELECT COUNT(*) FROM "requisitions" WHERE "requisitions"."e...: SELECT COUNT(*) FROM "requisitions" WHERE "requisitions"."emp_id" = $1 
ActiveRecord::StatementInvalid: PG::UndefinedColumn: ERROR: column requisitions.emp_id does not exist 
LINE 1: SELECT COUNT(*) FROM "requisitions" WHERE "requisitions"."e... 
              ^
: SELECT COUNT(*) FROM "requisitions" WHERE "requisitions"."emp_id" = $1from F:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/activerecord-4.0.0/lib/active_record/connection_adapters/postgresql_adapter.rb:811:in `prepare

來源

2014-04-04 SNEH PANDYA

第一件事，belongs_to協會名稱應爲單數，所以你應該在你的Requisition模型有

belongs_to :emp

。

你也應該產生遷移增加emp_id列requisitions表：

bundle exec rails g migration add_emp_id_to_requisitions emp:references

並運行它：

bundle exec rake db:migrate

現在，給你emp變量保存Emp例如，你可以指望這個emp的requisition作者：

emp.requisitions.count

來源

2014-04-04 06:15:32

我已添加我的日誌.. –

@SNEHPANDYA您忘記了遷移。我擴大了我的答案。 –

完美答案.. –

從軌道中的兩個表中獲取數據？

回答

相關問題