列出Mongoid模型中的动态属性

Question

我已经阅读了文档,我找不到具体的方法来解决这个问题.我已经为模型添加了一些动态属性,我希望能够遍历所有这些属性.

所以,举一个具体的例子:

class Order
  include Mongoid::Document

  field :status, type: String, default: "pending"
end

然后我做以下事情:

Order.new(status: "processed", internal_id: "1111") 

后来我想回来并且能够获得所有动态属性的列表/数组(在这种情况下,"internal_id"就是它).

我还在挖,但我很想知道是否有其他人已经解决了这个问题.

Answer 1

这将只给出给定记录x的动态字段名称:

dynamic_attribute_names = x.attributes.keys - x.fields.keys

如果使用其他Mongoid功能,则需要减去与这些功能关联的字段:例如Mongoid::Versioning:

dynamic_attribute_names = (x.attributes.keys - x.fields.keys) - ['versions']

仅获取动态属性的键/值对:

确保克隆属性()的结果,否则你修改x !!

attr_hash = x.attributes.clone  #### make sure to clone this, otherwise you modify x !!
dyn_attr_hash = attr_hash.delete_if{|k,v| ! dynamic_attribute_names.include?(k)}

或者在一行中:

x.attributes.clone.delete_if{|k,v| ! dynamic_attribute_names.include?(k)}

Answer 2

只需在您的模型中包含以下内容:

module DynamicAttributeSupport

  def self.included(base)
    base.send :include, InstanceMethods
  end

  module InstanceMethods
    def dynamic_attributes
      attributes.keys - _protected_attributes[:default].to_a - fields.keys
    end

    def static_attributes
      fields.keys - dynamic_attributes
    end
  end

end

这里有一个规范:

require 'spec_helper'

describe "dynamic attributes" do

  class DynamicAttributeModel
    include Mongoid::Document
    include DynamicAttributeSupport
    field :defined_field, type: String
  end

  it "provides dynamic_attribute helper" do
    d = DynamicAttributeModel.new(age: 45, defined_field: 'George')
    d.dynamic_attributes.should == ['age']
  end

  it "has static attributes" do
    d = DynamicAttributeModel.new(foo: 'bar')
    d.static_attributes.should include('defined_field')
    d.static_attributes.should_not include('foo')
  end

  it "allows creation with dynamic attributes" do
    d = DynamicAttributeModel.create(age: 99, blood_type: 'A')
    d = DynamicAttributeModel.find(d.id)
    d.age.should == 99
    d.blood_type.should == 'A'
    d.dynamic_attributes.should == ['age', 'blood_type']
  end
end