Question

让模型Quote具有属性[price, description]

让模型Invoice具有属性[price, description, priority]

让invoice来自模型Invoice的对象具有属性{price: 10, description: 'lamp', priority: 10}

invoice = {price: 10, description: 'lamp', priority: 10}

假设我想将invoice个属性复制到新的quote。

quote = Quote.new(invoice.attributes)

这会引发priority在模型Quote中不存在的错误。

如何将invoice属性复制到新的quote，但只复制quote可以接受的属性？

Answer 1

您只能select Quote拥有的属性：

Quote.new(invoice.attributes.select{ |key, _| Quote.attribute_names.include? key })

As noted by @aceofspades（但不是动态解决方案），您也可以使用ActiveSupport的slice：

Quote.new(invoice.attributes.slice(*Quote.attribute_names))

Answer 2

ActiveSupport的切片方法怎么样？

quote = Quote.new(invoice.attributes.slice(:price, :description))

甚至

quote = Quote.new(invoice.attributes.slice(*Quote.accessible_attributes))

Answer 3

直截了当的方式是这样的：

source = invoice.attributes
target = (source.keys & Quote.attribute_names).inject({}) {|target, key| target[key] = source[key]; target }
quote = Quote.new(target)

Answer 4

sample_plan = Plan.last  # it contains object we want to convert
new_plan = Addon.new(sample_plan.attributes.except(:id)) # remove that particular column which is not common else you can get attribute errors.
new_plan # you can get the copy object with data in new one.

Rails：使用“attributes”方法将属性从对象复制到另一个对象

4 个答案: