activerecord

ZhaoWei-2020-02-03

由 做~自己de王妃 提交于 2020-02-25 21:30:24
MybatisPlus Mybatis-Plus（简称MP）是一个 Mybatis 的增强工具 ，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。 MybatisPlus的特性 操作简单，仅仅只需继承一个BaseMapper就可以完成，实现单一，批量，分页等等一系列操作，很大的减少了开发负担，但这仅仅是Mybatisplus的冰山一角，当我们需要多条件查询的时候，就会使用到MybatisPlus中强大的条件构造器EntityWrapper； 无侵入 ：Mybatis-Plus 在 Mybatis 的基础上进行扩展，只做增强不做改变，引入 Mybatis-Plus 不会对您现有的 Mybatis 构架产生任何影响，而且 MP 支持所有 Mybatis 原生的特性 依赖少 ：仅仅依赖 Mybatis 以及 Mybatis-Spring 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 预防Sql注入 ：内置 Sql 注入剥离器，有效预防Sql注入攻击 通用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 多种主键策略 ：支持多达4种主键策略（内含分布式唯一ID生成器），可自由配置，完美解决主键问题 支持热加载 ：Mapper

Need help to understand `has_and_belongs_to_many`

由 烂漫一生 提交于 2020-02-25 07:49:27
问题 There are three tables in the database: users (not empty) schedules (not empty) schedules_users ( empty ) user-model: class User < ActiveRecord::Base [...] has_and_belongs_to_many :schedules#has_many :schedules [...] end schedule-model: class Schedule < ActiveRecord::Base has_and_belongs_to_many :users#belongs_to :user end welcome-controller: (where I want to sort the schedules by date and time) class WelcomeController < ApplicationController def index if(current_user) @user_schedules =

Can't get result from $this->db->last_query(); codeigniter

由 邮差的信 提交于 2020-02-24 05:12:04
问题 Quite a simple thing to ask and must be discussed many times, but I still not able to get the result of $this->db->last_query();. $this->db->select('count(*) as totalverified,res_sales.upduser, employee.name'); $this->db->from('res_sales'); $this->db->join('employee','employee.user_id = res_sales.upduser'); $this->db->where('date>=', $fromdate); $this->db->where('date<=', $todate); $this->db->where('verificationnumber<>', ''); $this->db->where('verificationnumber<>', NULL); $this->db->group

Is rails 4 find_by deprecated?

由 僤鯓⒐⒋嵵緔 提交于 2020-02-21 10:36:06
问题 I heard that find_by is deprecated is this true? I have been thinking of alternatives such as creating for each find a different method, e.g.: before: Model.find_by_username 'username' after: --in model--- class << self def by_username username where(:username => username).first end end is it a good naming? what names do you give for such methods? Update: find_by is not deprecated but the announcement could have been clearer! 回答1: According to the Rails 4 Release Notes: All dynamic methods

ActiveRecord: Alternative to find_in_batches?

由 蓝咒 提交于 2020-02-20 07:26:38
问题 I have a query that loads thousands of objects and I want to tame it by using find_in_batches : Car.includes(:member).where(:engine => "123").find_in_batches(batch_size: 500) ... According to the docs, I can't have a custom sorting order: http://www.rubydoc.info/docs/rails/4.0.0/ActiveRecord/Batches:find_in_batches However, I need a custom sort order of created_at DESC . Is there another method to run this query in chunks like it does in find_in_batches so that not so many objects live on the

How can i track the object details?

由 核能气质少年 提交于 2020-02-08 11:04:38
问题 I have Student Model Like class Student < ApplicationRecord belongs_to :classroom, optional: true end Classroom model Like: class Classroom < ApplicationRecord has_many :students,dependent: :destroy has_many :teachers, dependent: :destroy belongs_to :school, dependent: :destroy end Now i wants to track the every students of every classroom. i want the following detail with notice and date and display in the show page http://localhost:3000/school/1/students/68 For exe. student which has id:68

How can i track the object details?

由 别来无恙 提交于 2020-02-08 11:04:38
问题 I have Student Model Like class Student < ApplicationRecord belongs_to :classroom, optional: true end Classroom model Like: class Classroom < ApplicationRecord has_many :students,dependent: :destroy has_many :teachers, dependent: :destroy belongs_to :school, dependent: :destroy end Now i wants to track the every students of every classroom. i want the following detail with notice and date and display in the show page http://localhost:3000/school/1/students/68 For exe. student which has id:68

How can i track the object details?

由 无人久伴 提交于 2020-02-08 11:04:32
问题 I have Student Model Like class Student < ApplicationRecord belongs_to :classroom, optional: true end Classroom model Like: class Classroom < ApplicationRecord has_many :students,dependent: :destroy has_many :teachers, dependent: :destroy belongs_to :school, dependent: :destroy end Now i wants to track the every students of every classroom. i want the following detail with notice and date and display in the show page http://localhost:3000/school/1/students/68 For exe. student which has id:68

How can i track the object details?

由 戏子无情 提交于 2020-02-08 11:04:17
问题 I have Student Model Like class Student < ApplicationRecord belongs_to :classroom, optional: true end Classroom model Like: class Classroom < ApplicationRecord has_many :students,dependent: :destroy has_many :teachers, dependent: :destroy belongs_to :school, dependent: :destroy end Now i wants to track the every students of every classroom. i want the following detail with notice and date and display in the show page http://localhost:3000/school/1/students/68 For exe. student which has id:68

where should ActiveRecord::Base.transaction be?

由 ≯℡__Kan透↙ 提交于 2020-02-07 17:16:06
问题 I have three models: List, Food, and Quantity. List and Food are associated through Quantity via has_many :through. So each Quantity has three params: food_id, list_id, and amount (an integer). My aim is to create a new Quantity (associated with that list) each time a list is created. I wish to do this using a transaction so that all objects must be successfully created or else none will be. My main question is: where in my code should I write this transaction? I think it should be in the
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