Rails4：在has_many模型验证器上使用has_many保存对象失败(Rails4: Save object with has_many fails on the has_many model validator)

 我试图一次保存两个模型（一个到多个）。 我的代码如下所示： 
 
@submission = Submission.new(submission_params)

@submission_asset = @submission.attachments.new(submission_asset_params)
@submission_asset.attachment_type = 'submission_asset'

if @submission.save
  # render or redirect here
else
  @submission.errors
end
 
 但是当我运行这个时，我收到此错误@messages={:attachments=>["is invalid"]} 。 我想这是因为我的附件模型有这个： 
 
# Attachment model snippet
validates :attachable_id, :attachable_type, presence: true
 
 但是要确保它附加到Submission 。 但是，当我删除或注释掉验证时，它可以工作并保存两个模型和关联。 
 
 我如何进行此保存？ 
 
 编辑 
 
class Submission < ActiveRecord::Base
  has_many :attachments, as: :attachable, dependent: :destroy
end

class Attachment < ActiveRecord::Base
  belongs_to :attachable, polymorphic: true

  validates :attachable_id, :attachable_type, presence: true
end

I'm trying to save two models (one to many) in one time. My code looks like this:
 
@submission = Submission.new(submission_params)

@submission_asset = @submission.attachments.new(submission_asset_params)
@submission_asset.attachment_type = 'submission_asset'

if @submission.save
  # render or redirect here
else
  @submission.errors
end
 
But when I run this I get this error @messages={:attachments=>["is invalid"]}. I think it's because my attachment model has this:
 
# Attachment model snippet
validates :attachable_id, :attachable_type, presence: true
 
But it's to ensure it is attached to a Submission. But when I remove or comment out the validation it works and saves the two models and the association.
 
How do I make this save?
 
EDIT
 
class Submission < ActiveRecord::Base
  has_many :attachments, as: :attachable, dependent: :destroy
end

class Attachment < ActiveRecord::Base
  belongs_to :attachable, polymorphic: true

  validates :attachable_id, :attachable_type, presence: true
end

原文：https://stackoverflow.com/questions/18783394