当改变连接表中的属性值时，Rails 5 会插入而不是更新。

Question

我有一个使用has_many :through关联的HABTM关系。我在更新联接表中的属性时遇到了问题，因为它没有更新记录，只是在表中插入了一条新记录，造成了重复。

我尝试在创建索引和添加验证时使用UNIQUE约束，但现在当我更新记录时，我得到一个验证错误或错误。ActiveRecord::RecordNotUnique in BatchesController#updateMysql2::Error: 重复的条目

为了提供一些背景资料，我有4张表：manufacturing_orders、order_products、batches和batches_order_products（连接表）。

• 我有4张表：制造订单、订单产品、批次和批次订单产品（连接表）。
• 一个制造订单有很多订单产品。
• 一个制造订单有很多订单产品，一个制造订单也有很多批次。
• 批次有许多订单产品。
• 当我创建一个批次时，我复制了所有属于同一个制造订单的订单产品，在表格中，我可以为每个订单产品分配一个数量。

因此，创建看起来工作正常，但当我更新任何数量时，它只是再次插入整个关系，而不是更新现有的一个。

模型 制造_订单.rb:

class ManufacturingOrder < ApplicationRecord
  has_many :batches, inverse_of: :manufacturing_order, dependent: :destroy
  has_many :order_products, inverse_of: :manufacturing_order, dependent: :destroy

  accepts_nested_attributes_for :order_products
  accepts_nested_attributes_for :batches
end

型号 order_product.rb:

class OrderProduct < ApplicationRecord

  belongs_to :manufacturing_order

  has_many :batches_order_products
  has_many :batches, :through => :batches_order_products
end

型号 batch.rb:

class Batch < ApplicationRecord
  belongs_to :manufacturing_order

  has_many :batches_order_products
  has_many :order_products, :through => :batches_order_products

  accepts_nested_attributes_for :batches_order_products
end

模型 批次_订单_产品.rb:

class BatchesOrderProduct < ApplicationRecord
  belongs_to :batch
  belongs_to :order_product

  validates :batch_id, uniqueness: { scope: :order_product_id }
end

控制器 batches_controller.rb:

class BatchesController < ApplicationController
  def new
    manufacturing_order = ManufacturingOrder.find(params[:manufacturing_order_id])
    order_products = manufacturing_order.order_products
    @batch = Batch.new({
      manufacturing_order: manufacturing_order,
      order_products: order_products
    })
  end

  def create
    @batch = Batch.new(load_params)
    if @batch.save
      flash[:notice] = crud_success
      redirect_to action: :index
    else
      flash[:error] = @batch.errors.full_messages.to_sentence
      render action: :new
    end
  end

  def edit
    @batch = Batch.find(params[:id])
  end

  def update
    @batch = Batch.find(params[:id])
    if @batch.update_attributes(load_params)
      flash[:notice] = crud_success
      redirect_to action: :index
    else
      flash[:error] = @batch.errors.full_messages.to_sentence
      render action: :edit
    end
  end

  private
  def load_params
    params.require(:batch)
    .permit(:name,
      :date,
      :manufacturing_order_id,
      :status,
      order_products: [],
      order_products_ids: [],
      batches_order_products_attributes: [:id, :quantity, :order_product_id]
      )
  end
end

这是batches的表单。

  = bootstrap_form_for([@batch.manufacturing_order, @batch]) do |f|
    = f.hidden_field :manufacturing_order_id
       = f.text_field :name, label: 'Name'
        = f.text_field :date
    table
      thead
        tr
          th= "Product"
          th= "Quantity"
    tbody
      = f.fields_for :batches_order_products do |bop|
        = bop.hidden_field :order_product_id
      tr
        td
          = bop.object.order_product.name
        td
          = bop.text_field :quantity

  = f.submit 'Save'

任何帮助将是非常感激的。谢谢你的帮助

UPDATE:这些是提交编辑表单时传递的参数。有什么线索吗？

{"utf8"=>"✓",
 "_method"=>"patch",
 "batch"=>
  {"manufacturing_order_id"=>"8",
   "name"=>"MAS",
   "date"=>"07/05/2020",
   "batches_order_products_attributes"=>
    {"0"=>{"order_product_id"=>"12", "quantity"=>"77777777", "id"=>""},
     "1"=>{"order_product_id"=>"13", "quantity"=>"9.0", "id"=>""},
     "2"=>{"order_product_id"=>"14", "quantity"=>"7.0", "id"=>""}}},
 "commit"=>"Guardar",
 "manufacturing_order_id"=>"8",
 "id"=>"7"}

EDIT 2：我更新了嵌套表单，将id包含在这样的隐藏字段中。

= f.fields_for :batches_order_products do |bop|
  = bop.hidden_field :order_product_id
  = bop.hidden_field :id, value: @batch.id

  = bop.object.order_product.name
  = bop.text_field :quantity, label: ''

但是现在Rails在更新的时候会抱怨这个。

ActiveRecord::StatementInvalid in BatchesController#update

Mysql2::Error: Unknown column 'batches_order_products.' in 'where clause': SELECT `batches_order_products`.* FROM `batches_order_products` WHERE `batches_order_products`.`batch_id` = 9 AND `batches_order_products`.`` IN ('9', '9', '9', '9', '9') 

我不知道为什么Rails要在SQL查询中添加最后那个奇怪的部分。

Answer 1

所以我终于想明白了。

问题是联接表需要一个ID列来引用。该表有一个batch_id和order_product_id的索引，但由于某些原因，它没有工作，ActiveRecord正在寻找一个ID。添加后就解决了这个问题。

谢谢@max给出的一些要点，可以参考一下。

class AddIndexToBatchesOrderProductsJoinTable < ActiveRecord::Migration[5.2]
  def change
    # add_index :batches_order_products, [:batch_id, :order_product_id], unique: true
    add_column :batches_order_products, :id, :primary_key
  end
end