RAILS:具有现有记录的新方法中的嵌套属性 [英] RAILS: Nested attributes in new method with existing record

问题描述

我有模型:

Frame.rb

belongs_to :manufacturer, foreign_key: 'model'
accepts_nested_attributes_for :manufacturer, :reject_if => proc { |obj| obj.blank? }

当我尝试与现有制造商创建新框架时，出现错误:

When i try to create new Frame with existing manufacturer i get an error:

Frame.new({name: 'Name of the frame', manufacturer_attributes: {id:2}})

错误:

Couldn't find Manufacturer with ID=2 for Frame with ID=

推荐答案

问题是Frame.new是一条新记录，当ActiveRecord到达参数manufacturers_attributes时对 Frame.new 的关联 manufacturers_attributes 执行查找，该关联未保存，因此没有用于执行查找的 id.

The problem is that Frame.new is a new record, when ActiveRecord reaches the parameter manufacturers_attributes it performs a lookup on the association manufacturers_attributes for Frame.new which is unsaved and hence has no id with which to perform the lookup.

我建议从现有的 manufacturer 记录开始，然后像这样简单地创建框架 manufacturer.frames.create(frame_params)(假设是一对多关系).

I recommend starting with the existing manufacturer record and simply create the frame like so manufacturer.frames.create(frame_params) (assuming a one-to-many relationship).

但是，如果您必须这样做，您可以像这样覆盖 manufacturer_attributes 方法:

However, if you must do it this way you can overwrite the manufacturer_attributes method like so:

accepts_nested_attributes_for :manufacturer
  def manufacturer_attributes=(attributes)
    if attributes['id'].present?
      self.manufacturer = Manufacturer.find(attributes['id'])
    end
    super
  end

因此，您可以在原始 manufacturer_attributes 尝试访问新记录上的制造商之前分配制造商，这在之前导致了错误.

Thus, you assign the manufacturer before the original manufacturer_attributes tries to access it on the new record, which previously caused the error.

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