activerecord

How to limit has_one association to a single record

由 与世无争的帅哥 提交于 2021-01-04 18:41:32
问题 I am having trouble with retaining only a single record in a has_one relationship Example Categories and question A question belongs_to a category, and a category has_one question In reality as seen in a system i am building even though the has_one relationship exists, there comes a case where i have multiple questions that belong to a category. Shouldn't the has_one relationship limit them to just one record? If not, then how can i make sure that i always keep one record? EDIT Please note

How to save a nested resource in ActiveRecord using a single form (Ruby on Rails 5)

由 ☆樱花仙子☆ 提交于 2021-01-04 09:14:15
问题 I have two entities with a many-to-one relationship. User has many Addresses. When creating a User I want the form to also create a single Address. The entities are nested. Approach 1: The code below works, but only saves the User, no associated Address. Reading around, I thought that the accepts_nested_attributes_for would automatically save the address. I'm not sure, but it may be that this isn't working because the parameters I'm getting into the Controller don't actually appear to be

Rails - Delete all Records that Meet a Condition

由 ⅰ亾dé卋堺 提交于 2020-12-27 12:13:48
问题 How do you write in the Rails way? I have a model - Managers. I want to delete all records from Managers that meet the condition that manager_level is 5. Thank you. 回答1: I think it is better to use destroy instead of delete because destroy will delete current object record from db and also its associated children record from db (https://stackoverflow.com/a/22757656/5452072) Also delete will skip callbacks, but destroy doesn't. Manager.where(:manager_level => 5).destroy_all 回答2: Try this:

Rails - Delete all Records that Meet a Condition

由 落爺英雄遲暮 提交于 2020-12-27 12:10:06
问题 How do you write in the Rails way? I have a model - Managers. I want to delete all records from Managers that meet the condition that manager_level is 5. Thank you. 回答1: I think it is better to use destroy instead of delete because destroy will delete current object record from db and also its associated children record from db (https://stackoverflow.com/a/22757656/5452072) Also delete will skip callbacks, but destroy doesn't. Manager.where(:manager_level => 5).destroy_all 回答2: Try this:

Rails - Delete all Records that Meet a Condition

由 独自空忆成欢 提交于 2020-12-27 12:02:22
问题 How do you write in the Rails way? I have a model - Managers. I want to delete all records from Managers that meet the condition that manager_level is 5. Thank you. 回答1: I think it is better to use destroy instead of delete because destroy will delete current object record from db and also its associated children record from db (https://stackoverflow.com/a/22757656/5452072) Also delete will skip callbacks, but destroy doesn't. Manager.where(:manager_level => 5).destroy_all 回答2: Try this:

3分钟短文：Laravel ORM 模型用法纲要

由 喜欢而已 提交于 2020-11-19 07:27:25
引言 前两期为了说明laravel框架提供的数据库操作能力，直接使用DB门面操作， 而没有引入更为强大的eloquent orm功能。从本期开始，我们就分次把 eloquent的一些简要知识点，为大家提炼演示一下。主要以代码为主，配以简要说明。 学习时间 Eloquent其实是一个 ActiveRecord 类型的 ORM。这是一个位于数据库操作之上的一个中间层， 不仅仅是对于整张表的操作，更能细化到每行记录的增删改查。 创建一个模型类非常简单，只用继承系统的模型就可以了： use Illuminate\Database\Eloquent\Model; class Contact extends Model {} 因为遵循的是 约定大于配置 的惯例，所以上述模型如不指定表名，默认就是默认数据库的 contacts 表了。 对于数据库插入新条目，则可以便捷地使用模型的方法执行，比如下面这样： public function save(Request $request) { $contact = new Contact(); $contact->first_name = $request->input('first_name'); $contact->last_name = $request->input('last_name'); $conatct->email = $request

给你的 MyBatis-Plus 装上批量插入的翅膀

由 浪尽此生 提交于 2020-11-11 14:43:46
大家有用过MyBatis-Plus（简称MP）的都知道它是一个MyBatis的增强工具,旨在MyBatis的基础上只做增强不做改变,为简化开发、提高效率而生。 特点 无侵入：只做增强不做改变，引入它不会对现有工程产生影响，如丝般顺滑 损耗小：启动即会自动注入基本 CURD，性能基本无损耗，直接面向对象操作 强大的 CRUD 操作：内置通用 Mapper、通用 Service，仅仅通过少量配置即可实现单表大部分 CRUD 操作，更有强大的条件构造器，满足各类使用需求 支持 Lambda 形式调用：通过 Lambda 表达式，方便的编写各类查询条件，无需再担心字段写错 支持主键自动生成：支持多达 4 种主键策略（内含分布式唯一 ID 生成器 - Sequence），可自由配置，完美解决主键问题 支持 ActiveRecord 模式：支持 ActiveRecord 形式调用，实体类只需继承 Model 类即可进行强大的 CRUD 操作 支持自定义全局通用操作：支持全局通用方法注入（ Write once, use anywhere ） 内置代码生成器：采用代码或者 Maven 插件可快速生成 Mapper 、 Model 、 Service 、 Controller 层代码，支持模板引擎，更有超多自定义配置等您来使用 内置分页插件：基于 MyBatis 物理分页，开发者无需关心具体操作

puma(5300✨) Rails的一个多线程，高并发处理的web server

由 僤鯓⒐⒋嵵緔 提交于 2020-10-28 10:36:36
https://github.com/puma/puma 在开发和产品环境下，Puma是一个简单，快速，多线程，并高并发highly concurrent HTTP1.1server for Ruby/Rack程序。 什么是多线程？ multithreading 指从软件或者硬件上实现多个线程并发执行的技术。从而整体提升处理效能。 软件多线程：即使处理器只能运行一个线程，但操作系统可以通过快速在不同线程之间进行切换，由于间隔时间很小，给用户造成一种多个线程同时运行的假象。这样的程序运行机制被称为软件多线程。 多任务可以由多进程完成，也可以由一个进程内的多线程完成。 进程是由若干线程组成的，一个进程至少有一个线程。 单进程单线程：一个人在一个桌子上吃菜； 单进程多线程：多个人在一个桌子上吃菜；容易发生争抢，即资源共享就会发生冲突争抢。 多进程单线程：多个人在各自的桌子上吃菜； gem 'puma', '~> 3.11' gem 'mina-puma', '~> 1.1.0', require: false ⚠️require: false的选项是什么用途？ 答案： 具体见：stackoverflow 把这个gem安装了，但不加载load。 你bundler时，不会调用require 'mina-puma'命令。什么时候需要用到这个library，手动加载这个命令。
订阅 activerecord