顯示在他們的順序加入數據記錄在PostgreSQL和Ruby on Rails創建

Question

我在PostgreSQL數據庫三個表：

1. 成員

   • ID
   • FIRST_NAME
   • 姓氏
   • created_at
次

2. 付款（贊借記）

   • ID
   • member_id
   • 量
   • created_at
   • 類型

3. 費用（贊信用）

   • ID
   • member_id
   • 量
   • created_at
   • 型

我想向他們展示在一個視圖中說賬單： ，我用下面的查詢：

select * from members as t1 left join payments as t2 on (t1.id=t2.member_id) left join fees as t3 on (t1.id=t3.member_id) 

，它顯示了我下面的結果：

id | Amount | created_at | Type 
1 100  25-12-2013 Fee 
2 100  29-12-2013 Fee 
3 100  25-12-2013 Payment 
4 100  23-12-2013 Payment 

但問題是，它顯示了第一個收費記錄，然後付款，而我需要它應該是爲了通過created_at，它應該是象下面這樣：

id | Amount | created_at | Type 
1 100  23-12-2013 Payment 
2 100  25-12-2013 Fee 
3 100  25-12-2013 Payment 
4 100  29-12-2013 Fee 

車型

下面是詳細信息：

class Fee < ActiveRecord::Base 

    # Setup accessible (or protected) attributes for your model 
    attr_accessible :member_id,:fee_type,:amount,:reason,:details,:date 

    # Setup relations with relative models 
    belongs_to :member 

    # Validates rule here 
    validates_numericality_of :member_id,:fee_type,:amount 

    validates :reason, 
    :format => {:with => /^[-a-zA-Z0-9_ ]+$/ }, 
    :length => {:maximum => 255}, 
    :presence =>true 
    validates :details, 
    :format => {:with => /^[-a-zA-Z0-9_ ]+$/ }, 
    :length => {:maximum => 255}, 
    :allow_blank =>true 
    validates :amount, 
    :presence => true 
    validates :member_id, 
    :presence => true 
    validates :date, 
    :presence => true 

    # Search start here 
    self.per_page = 10 

end 

class Payment < ActiveRecord::Base 

    # Setup accessible (or protected) attributes for your model 
    attr_accessible :member_id,:payment_category_id,:payment_type_id,:payment_date,:amount,:notes,:is_send_email,:last_sent,:date_deposite 
    # Setup relations with relative models 
    belongs_to :payment_type 
    belongs_to :payment_category 
    belongs_to :member 

    # Validates rule here 
    validates_numericality_of :member_id,:payment_category_id,:payment_type_id,:amount 

    validates :notes, 
    :format => {:with => /^[-a-zA-Z0-9_ ]+$/ }, 
    :length => {:maximum => 255}, 
    :allow_blank =>true 
    validates :amount, 
    :presence => true, 
    :length => {:maximum => 15} 
    validates :member_id, 
    :presence => true 
    validates :payment_date, 
    :presence => true 

    # Pagiination start here 
    self.per_page = 10 

end 

class Member < ActiveRecord::Base 

    has_many :payment, dependent: :destroy, -> { order :created_at } 
    has_many :fee, dependent: :destroy, -> { order :created_at } 
    has_many :events, :through => :participants 

end 

Answer 1

根據您多少記錄拉出，你也可以做將數據從數據庫中拉出後進行排序，例如：

transactions = member.payments + member.fees 
transactions = transactions.flatten.sort_by(&:created_at) 

Answer 2

如果我是你，我會用ActiveRecord Associations這樣的：

#app/models/member.rb 
Class Member < ActiveRecord::Base 
    has_many :payments, -> { order :created_at } 
    has_many :fees, -> { order :created_at } 
end 

#app/models/payment.rb 
Class Payment < ActiveRecord::Base 
    belongs_to :member 
end 

#app/models/fee.rb 
Class Fee < ActiveRecord::Base 
    belongs_to :member 
end 

這應該給你拉你需要它有序的關聯數據，這樣的能力：

@member = Member.find 1 
@member.payments #-> should be ordered by created_at