Ruby on rails 嵌套形式/批量分配，验证麻烦，已通过多次

好吧，所以我很难理解我哪里出了问题。我的关联设置正确，新订单工作正常（注意：如果两个字段都已填写）。如果我只填写一个字段，对于一项订单，批量分配将失败。我希望最终能够有3个字段，但如果只填写了其中的1或2个字段，一切都会顺利进行，空字段将被忽略。我花了几个小时试图理解这一点，现在我想尽一切办法来调试/理解这件事

视图/表单：new.html.erb

<%= form_for @order do |f| %>
  <%= f.hidden_field :date, :value => Time.now %>
  <%= f.fields_for :order_items do |f| %>
    <%= f.collection_select :item_id, Item.all, :id, :item_type, :include_blank => true %>
    <%= f.label "Quantity: "%>
    <%= f.text_field :quantity %><br>
  <% end %>
  <%= f.submit %>
<% end %>

型号：

class Order < ApplicationRecord
  has_many :order_items
  has_many :items, through: :order_items
  belongs_to :account

  def order_items_attributes=(order_items_attributes)
    order_items_attributes.each do |i, order_item_attributes|
      #binding.pry
      self.order_items.build(order_item_attributes)
    end
  end
end

class OrderItem < ApplicationRecord
  belongs_to :order
  belongs_to :item

  **NOTE: ALL THESE VALIDATIONS SEEM TO BE USELESS**
  #validates :item_id, :presence => {:message => "You must choose"}
  #validates :quantity, :presence => {:message => "You must choose"}
  #validates :order_id, :presence => {:message => "You must choose"}
  #validates_presence_of :item_id, :message => "You must choose an item"
  #validates_presence_of :quantity, :message => "You must enter the quantity"
end

class User < ApplicationRecord
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
     :recoverable, :rememberable, :trackable, :validatable

  has_one :account
  has_many :orders, through: :account
end

class Account < ApplicationRecord
  belongs_to :user
  has_many :orders, dependent: :destroy
end

class Item < ApplicationRecord
  #belongs_to :order
  has_many :order_items
end

类顺序{:message=>“您必须选择”}
#验证：数量，：状态=>{：消息=>“您必须选择”}
#验证：order_id，：presence=>{:message=>“您必须选择”}
#验证是否存在：item\u id，：message=>“您必须选择一个项目”
#验证是否存在：数量，：message=>“您必须输入数量”
结束
类用户<应用程序记录
#包括默认设计模块。其他可供选择的项目包括：
#：可确认、：可锁定、：超时和：全授权
设计：数据库可验证，可注册，
：可恢复，：可记忆，：可跟踪，：可验证
你有一个帐户吗
有很多订单，通过：：帐户
结束
类帐户<应用程序记录
属于：用户
有很多：订单，依赖：：销毁
结束
类项<应用程序记录
#属于：秩序
有很多：订购物品
结束

我希望一切都清楚了。我还是一个初学者，所以任何帮助都将不胜感激！谢谢

class Order < ApplicationRecord
  has_many :order_items
  has_many :items, through: :order_items
  belongs_to :account

  def order_items_attributes=(order_items_attributes)
    order_items_attributes.each do |i, order_item_attributes|
      #binding.pry
      self.order_items.build(order_item_attributes)
    end
  end
end

class OrderItem < ApplicationRecord
  belongs_to :order
  belongs_to :item

  **NOTE: ALL THESE VALIDATIONS SEEM TO BE USELESS**
  #validates :item_id, :presence => {:message => "You must choose"}
  #validates :quantity, :presence => {:message => "You must choose"}
  #validates :order_id, :presence => {:message => "You must choose"}
  #validates_presence_of :item_id, :message => "You must choose an item"
  #validates_presence_of :quantity, :message => "You must enter the quantity"
end

class User < ApplicationRecord
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
     :recoverable, :rememberable, :trackable, :validatable

  has_one :account
  has_many :orders, through: :account
end

class Account < ApplicationRecord
  belongs_to :user
  has_many :orders, dependent: :destroy
end

class Item < ApplicationRecord
  #belongs_to :order
  has_many :order_items
end