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Rails 5 API-has_many through create操作返回2条记录,尽管只有1条记录保存在数据库中

ruby-on-rails-5.2 many-to-many json ruby-on-rails

rmcsharry · 技术社区 · 6 年前

我有以下三种型号的M2M关联

Customer -> Residences <- Properties

属性模型还与地址相关:

class Address < ApplicationRecord
  has_one :property
end

在创建属性之前,客户将始终存在。属性是通过提交地址创建的。

这里是控制器操作,除了成功之外,渲染始终返回2个属性(即基本上2个居住记录)。

但是,数据库中只有一个。我知道这和 stale objects ,但不知道如何解决。

我试着加上 @customer.reload 和 @customer.reload.residences 和 @customer.reload.properties 但还是有两张唱片。

  # POST /customers/:id/properties
  def create
    @customer = set_customer
    Customer.transaction do
      address = Address.find_by_place_id(address_params[:place_id]) 
      if address.nil?
        @property = @customer.properties.create
        @property.address = Address.new(address_params)
        if @property.save
          @customer.reload
          render json: @customer, status: :created
        else
          render json: @property.errors, status: :unprocessable_entity
        end
      else
        # irrelevant code to the problem
      end
    end
  end

def set_customer
  Customer.find(params[:customer_id])
end

评论 this question (from@swaps)表示使用<<而不是create有时会导致重复,但无论我使用哪种方法,我总是得到2。

编辑

我设法让它像这样工作,但这感觉像一个黑客:

    if @property.save
      @customer = set_customer
      render json: @customer, status: :created
    else

**更新-型号**

class Customer < ApplicationRecord
  has_many :residences
  has_many :properties, through: :residences
end

class Residence < ApplicationRecord
  belongs_to :customer
  belongs_to :property
end

class Property < ApplicationRecord
  belongs_to :address
  has_many :residences
  has_many :customers, through: :residences
end

class Address < ApplicationRecord
  has_one :property
  has_one :location # ignore this, not relevant
end

2 回复 | 直到 6 年前

aridlehoover 6 年前

您正在尝试手动执行activerecord可以自动执行的操作 accepts_nested_attributes_for . 它甚至可以和 has_many through 操作。

class Customer < ApplicationRecord
  has_many: :residences, inverse_of :customer
  has_many: :properties, through: :residences

  accepts_nested_attributes_for :residences
end

class Residence < ApplicationRecord
  belongs_to :customer
  belongs_to :property

  validates_presence_of :customer
  validates_presence_of :property

  accepts_nested_attributes_for :property
end

class Property < ApplicationRecord
  has_one :address
  has_many :residences
  has_many :customers, through: :residences

  accepts_nested_attributes_for :address
end

class Address < ApplicationRecord
  belongs_to :property
end

class CustomersController < ApplicationController
  def create
    customer = Customer.new(customer_params)
    if customer.save
      redirect_to customer, notice: 'Customer saved!'
    else
      render :new
    end
  end

  def customer_params
    params.require(:customer).permit(
      name:, ..., 
      residences_attributes: [
        property_attributes: [
          name, ..., 
          address_attributes: [
            street, city, state, postal_code, ...
          ]
        ]
      ]
    )
  end
end

参考文献:

mehedi 6 年前

你能试试这个吗?

def create
  @customer = set_customer
  Customer.transaction do
    address = Address.find_by_place_id(address_params[:place_id]) 
    if address.nil?
      @customer.properties.new(address_params)
      if @customer.save
        render json: @customer, status: :created
      else
        render json: @customer.errors, status: :unprocessable_entity
      end
    else
      # irrelevant code to the problem
    end
  end
end

我在想你真的需要@property实例变量吗?是给你看文件的吗?

更新1

请您将您的客户和居住模式添加如下:

客户模型

class Customer < ApplicationRecord
  has_many :residences
  has_many :properties, through: :residences
end

住宅模型

class Residence < ApplicationRecord
  belongs_to :customer
  belongs_to :property
end

rmcsharry 6 年前

问题是activerecord中的对象与保存后数据库中的对象比较陈旧。

“.reload”不起作用,我必须使用我的黑客强制activerecord再次在数据库中找到客户,然后强制重新加载(我认为它会使ar缓存失效):

  def create
    @customer = set_customer
    Customer.transaction do
      address = Address.find_by_place_id(address_params[:place_id]) 
      if address.nil?
        @property = @customer.properties.create
        @property.address = Address.new(address_params)
        if @property.save!
          @customer = set_customer # force reload from db
          render json: @customer, status: :created
        end
      else
        address.update!(address_params)
        if @customer.properties.find_by_id(address.property.id).nil?
          # although we updated the address, that is just a side effect of this action
          # the intention is to create an actual residence record for this customer
          @customer.properties << address.property
          @customer = set_customer # force reload from db
          render json: @customer, status: :created
        else
          @customer.errors.add(:customer, 'already has that property address')
          render json: ErrorSerializer.serialize(@customer.errors), status: :unprocessable_entity
        end
      end
    end
  end

  def set_customer
    Customer.find(params[:customer_id])
  end