代码之家 › 专栏 › 技术社区 › Carmine Paolino

为什么在使用名称空间时在关联中指定完整的类名很重要

associations namespaces activerecord ruby ruby-on-rails

0

Carmine Paolino · 技术社区 · 16 年前

has_one 关联(这是一个虚构的例子):

class Person::Admin < ActiveRecord::Base
  has_one :person_monthly_revenue
  has_one :dude_monthly_niceness
  accepts_nested_attributes_for :person_monthly_revenue, :dude_monthly_niceness
end

class Person::MonthlyRevenue < ActiveRecord::Base
  belongs_to :person_admin
end

class Dude::MonthlyNiceness < ActiveRecord::Base
  belongs_to :person_admin
end

应用程序与后端通信,后端计算一些数据并返回一段JSON,如下所示:

{
    "dude_monthly_niceness": {
        "february": 1.1153232569518972, 
        "october": 1.1250217200558268, 
        "march": 1.3965786869658541, 
        "august": 1.6293418014601631, 
        "september": 1.4062771500697835, 
        "may": 1.7166279693955291, 
        "january": 1.0086401628086725, 
        "june": 1.5711510228365859, 
        "april": 1.5614525597326563, 
        "december": 0.99894169970474289, 
        "july": 1.7263264324994585, 
        "november": 0.95044938418509506
    }, 
    "person_monthly_revenue": {
        "february": 10.585596551505297, 
        "october": 10.574823016656749, 
        "march": 9.9125274764852787, 
        "august": 9.2111604702328922, 
        "september": 9.7905249446675153, 
        "may": 9.1329712474607962, 
        "january": 10.479614016604238, 
        "june": 9.3710235926961936, 
        "april": 9.5897372624830304, 
        "december": 10.052587677671438, 
        "july": 8.9508877843925561, 
        "november": 10.925339756096172
    }, 
}

from_json ,而不是 Person::Admin 对象的所有关联就绪后,我得到以下错误:

>> Person::Admin.new.from_json(json)
NameError: uninitialized constant Person::Admin::DudeMonthlyNiceness

有没有更好的方法来反序列化数据(我可以很容易地修改后端)

更新 :最初的标题是“如何将json反序列化为具有关联的ActiveRecord对象?”,但它最终是我指定关联时的错误,因此我更改了标题。

1 回复 | 直到 16 年前

1

Tatjana N. 16 年前

您的类位于不同的名称空间中。ActiveRecord转换 dude_monthly_niceness DudeMonthlyNiceness 在当前名称空间中初始化,这将 Person::Admin::DudeMonthlyNiceness

因此,您应该显式地为关联指定类名(不知道您使用的外键到底是什么,所以如果需要可以更改):

class Person::Admin < ActiveRecord::Base
  has_one :person_monthly_revenue, :class_name => "Person::MonthlyRevenue", :foreign_key => "person_admin_id"
  has_one :dude_monthly_niceness, :class_name => "Dude::MonthlyNiceness", :foreign_key => "person_admin_id"
  accepts_nested_attributes_for :person_monthly_revenue, :dude_monthly_niceness
end

另一件事是能够使用 accepts_nested_attributes_for ,您需要用\属性结束json对象:

{
    "dude_monthly_niceness_attributes": {
        "february": 1.1153232569518972, 
        ...
        "november": 0.95044938418509506
    }, 
    "person_monthly_revenue_attributes": {
        "february": 10.585596551505297, 
        ...
        "november": 10.925339756096172
    }, 
}