ActiveModel属性

Question

如何获取ActiveRecord属性方法功能？我有这个类：

class PurchaseForm 
    include ActiveModel::Validations 
    include ActiveModel::Conversion 
    extend ActiveModel::Naming 

    attr_accessor :name, 
       :surname, 
       :email 

    validates_presence_of :name 

    validates_format_of :email, :with => /^[-a-z0-9_+\.]+\@([-a-z0-9]+\.)+[a-z0-9]{2,4}$/i 

    def initialize(attributes = {}, shop_name) 
    if not attributes.nil? 
     attributes.each do |name, value| 
     send("#{name}=", value) 
    end 
    end 

    def persisted? 
    false 
    end 
end 

我需要做什么，有一个属性方法列出来自PurchaseForm对象的所有名称和值？

Answer 1

我已经设法解决问题与此代码：

class PurchaseForm 
    include ActiveModel::Validations 
    include ActiveModel::Conversion 
    extend ActiveModel::Naming 

    attr_accessor :attributes, 
       :name, 
       :surname, 
       :email 

    validates_presence_of :name 

    validates_format_of :email, :with => /^[-a-z0-9_+\.]+\@([-a-z0-9]+\.)+[a-z0-9]{2,4}$/i 

    def initialize(attributes = {}) 
    @attributes = attributes 
    end 

    def persisted? 
    false 
    end 
end 

Answer 2

岂不是更好地使用

include ActiveModel::Serialization 

def attributes 
    JSON.parse(self.to_json) 
end 

Answer 3

这里是重构变种：

class PurchaseForm 
    include ActiveModel::Model 

    def self.attributes 
    [:name, :surname, :email] 
    end 

    attr_accessor *self.attributes 

    # your validations 

    def to_hash 
    self.class.attributes.inject({}) do |hash, key| 
     hash.merge({ key => self.send(key) }) 
    end 
    end 
end 

现在您可以轻松使用此课程：

irb(main):001:0> a = PurchaseForm.new({ name: 'Name' }) 
=> #<PurchaseForm:0x00000002606b50 @name="Name"> 
irb(main):002:0> a.to_hash 
=> {:name=>"Name", :surname=>nil, :email=>nil} 
irb(main):003:0> a.email = 'user@example.com' 
=> "user@example.com" 
irb(main):004:0> a 
=> #<PurchaseForm:0x00000002606b50 @name="Name", @email="user@example.com"> 
irb(main):005:0> a.to_hash 
=> {:name=>"Name", :surname=>nil, :email=>"user@example.com"} 

更有甚者，如果你想使这种行为可重复使用，考虑.attributes提取和#to_hash方法分成单独的模块：

module AttributesHash 
    extend ActiveSupport::Concern 

    class_methods do 
    def attr_accessor(*args) 
     @attributes = args 
     super(*args) 
    end 

    def attributes 
     @attributes 
    end 
    end 

    included do 
    def to_hash 
     self.class.attributes.inject({}) do |hash, key| 
     hash.merge({ key => self.send(key) }) 
     end 
    end 
    end 
end 

现在，只需将其包括对你的模型，你就大功告成了：

class PurchaseForm 
    include ActiveModel::Model 
    include AttributesHash 

    attr_accessor :name, :surname, :email 

    # your validations 
end 

Answer 4

让我们试试这个

self.as_json

=> {:name=>"Name", :surname=>nil, :email=>"user@example.com"}

Answer 5

#instance_values可以做的工作：

class PurchaseForm 
    attr_accessor :name, :email 

    def attributes 
    instance_values 
    end 
end 

输出样本：

purchase.attributes #=> {"name"=>"John", "email"=>"john@example.com"}