Foo.new中的Params順序（params [：foo]），需要一個在另一個之前（Rails）

Question

我有一個問題，我不知道如何解決。它與未分類的params散列有關。

我有一個對象當我設置時間=時，我也想通過外部服務器請求來驗證它，它具有虛擬時間=屬性和虛擬eating_session =屬性。我在method（）方法的幫助下做了這樣的工作，它在其他服務器上進行查找並將所有可能的時間保存在@times變量中。

現在的問題是方法times（）需要eating_session屬性來找出哪些時間是有效的，但rails有時會在Reservation對象中有任何eating_session之前先調用times =方法，當我只是執行@預訂= Reservation.new（PARAMS [：預訂]）

class ReservationsController < ApplicationController 
    def new 
     @reservation = Reservation.new(params[:reservation]) 
     # ... 
    end 
end 

class Reservation < ActiveRecord::Base 
    include SoapClient 
    attr_accessor :date, :time 
    belongs_to :eating_session 

    def time=(time) 
     @time = times.find { |t| t[:time] == time } 
    end 

    def times 
     return @times if defined? @times 
     @times = [] 
     response = call_soap :search_availability { 
      # eating_session is sometimes nil 
      :session_id => eating_session.code, # <- HERE IS THE PROBLEM 
      :dining_date => date 
     } 
     response[:result].each do |result| 
      @times << { 
       :time => "#{DateTime.parse(result[:time]).strftime("%H:%M")}", 
       :correlation_data => result[:correlation_data] 
      } 
     end 
     @times 
    end 
end 

我不知道如何解決這一問題，任何幫助apriciated。

Answer 1

我經常做在這種情況下是推動相關的代碼到一個驗證：

class ReservationsController < ApplicationController 
    def new 
     @reservation = Reservation.new(params[:reservation]) 
     # ... 
    end 
end 

class Reservation < ActiveRecord::Base 
    include SoapClient 
    attr_accessor :date, :time 
    belongs_to :eating_session 
    validate :validate_time 

    def validate_time 
     errors.add_to_base "Time is invalid" unless @time = times.find { |t| t[:time] == time } 
    end 

    def times 
     return @times if defined? @times 
     @times = [] 
     response = call_soap :search_availability { 
      # eating_session is sometimes nil 
      :session_id => eating_session.code, # <- HERE IS THE PROBLEM 
      :dining_date => date 
     } 
     response[:result].each do |result| 
      @times << { 
       :time => "#{DateTime.parse(result[:time]).strftime("%H:%M")}", 
       :correlation_data => result[:correlation_data] 
      } 
     end 
     @times 
    end 
end