删除与外键约束依赖实体时pretty的错误：Rails的ActiveRecord的 [英] Rails ActiveRecord: pretty errors when deleting dependent entities with foreign keys constraints

问题描述

我在与外键约束的Rails应用程序几个表。例如，每个为了属于客户。有一个 costumer_id 的订单表列。

I have in Rails application several tables with foreign keys constraints. For example, every order belongs to a customer. There's a costumer_id column on the orders table.

当我删除，因为数据库约束的负荷消费与摆放顺序，MySQL返回错误：

When I delete a costumer with a placed order, because of database constraints, MySQL returns the error:

Mysql的::错误：无法删除或更新   父行，外键约束   失败（订单，约束    orders_ibfk_2 外部关键字   （ CUSTOMER_ID ）参考客户   （ ID ））

Mysql::Error: Cannot delete or update a parent row: a foreign key constraint fails (orders, CONSTRAINT orders_ibfk_2 FOREIGN KEY (customer_id) REFERENCES customers (id))

和丑陋的错误弹出在屏幕上，所有的堆栈跟踪那些东西  ActiveRecord的:: StatementInvalid在DevicesController＃摧毁...

And the ugly error pops up on the screen, with all stacktrace and those stuff ActiveRecord::StatementInvalid in DevicesController#destroy ...

我想知道是否有一个优雅的方式来对待这些约束错误，给人一种美丽的像你可以删除此对象，因为它关联到X

I'd like to know if there's an elegant way to treat these constraint errors, giving a beautiful like "you can delete this object because it is associated to X"

我怎么能这样做呢？

推荐答案

阵营中的前销毁回调：

class Customer < ActiveRecord::Base
  before_destroy :no_referenced_orders
  has_many :orders

  private

  def no_referenced_orders
    return if orders.empty?

    errors.add_to_base("This customer is referenced by order(s): #{orders.map(&:number).to_sentence}")
    false # If you return anything else, the callback will not stop the destroy from happening
  end
end

在控制器：

class CustomersController < ApplicationController
  def destroy
    @customer = Customer.find(params[:id])
    if @customer.destroy then
      redirect_to customers_url
    else
      render :action => :edit
    end
  end
end

这篇关于删除与外键约束依赖实体时pretty的错误：Rails的ActiveRecord的的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！