Analysis of Laravel's Eloquent ORM
这篇文章主要介绍了关于Laravel之Eloquent ORM ,有着一定的参考价值,现在分享给大家,有需要的朋友可以参考一下
一、ORM编程思想
1.1 Active Record 设计模式
Active Record
是一种数据访问设计模式,它可以帮助你实现数据对象Object
到关系数据库的映射。应用Active Record
时,每一个类的实例对象唯一对应一个数据库表的一行(一对一关系)。你只需继承一个abstract Active Record
类就可以使用该设计模式访问数据库,其最大的好处是使用非常简单
1.2 调试工具 Laravel Debugbar
https://github.com/barryvdh/l...
Installation:
composer require barryvdh/laravel-debugbar --dev
二、一对一关系映射
2.1 创建表
public function up() { Schema::create('profiles', function (Blueprint $table) { $table->increments('id'); $table->string('phone'); $table->unsignedInteger('user_id'); //显示的声明外键:通知数据库根据外键关联表和建立索引,提高运行速度 $table->foreign('user_id') ->references('id') ->on('users') ->onDelete('cascade'); $table->timestamps(); }); }
2.2 创建模型关系
2.2.1 正向关系绑定
public function profile() { return $this->hasOne(Profile::class); }
2.2.2 反向关系绑定
public function user() { return $this->belongsTo(User::class); }
2.3 外键
自定义外键:
return $this->hasOne(Profile::class,'显示指定自定义外键');
2.4 一对一测试
依赖注入Request $request
,获取当前登录用户$request->user()
Route::get('/test',function (Request $request){ //反向 // $profile = \App\Profile::find(1); // dd($profile->user); $user = $request->user(); // if (is_null($user->profile)){ // $user->profile()->create([ // 'phone' => '15801340269' // ]); // } //用firstOrCreate改进if $user->profile()->firstOrCreate(['user_id' => $user->id],[ 'phone' => '18363046291' ]); //访问属性一样访问方法 dd($user->profile); });
三、一对多关系映射
1:N hasMany(XXX:class) 反之:belongsTo(XXX:class)
3.1 面向对象方式绑定一对多的关系
四、多对多关系映射
中间表命名:按照A-Z
首字母排序
public function users() { return $this->belongsToMany(User::class); } public function habits() { return $this->belongsToMany(Habit::class); }
4.1 面向对象方式绑定多对多的关系
detach解绑,sync方法用的比较多,只保留1,2
4.2 访问多对多中间数据表
五、HasManyThrough对象桥接式穿越关联(远层一对多)
数据表:
countries id - integer name - string users id - integer country_id - integer name - string posts id - integer user_id - integer title - string
class Country extends Model { protected $fillable = ['name']; /** * 获得某个国家下所有的用户文章。 */ public function papers() { return $this->hasManyThrough(Paper::class,User::class); } }
$factory->define(App\Paper::class, function (Faker $faker) { return [ 'title' => $faker->sentence, 'user_id' => \App\User::all()->random()->id, ]; });
$factory->define(App\User::class, function (Faker $faker) { return [ 'name' => $faker->name, 'email' => $faker->unique()->safeEmail, 'country_id' => \App\Country::all()->random()->id, 'password' => '$2y$10$TKh8H1.PfQx37YgCzwiKb.KjNyWgaHb9cbcoQgpFlYg7B77UdFm', // secret 'remember_token' => str_random(10), ]; });
获取每个国家论文总数:
五、多样化的一对多关系映射(多态关联)
面向对象多态:运行时加载机制
更多:https://laravel-china.org/doc...
伪造数据:
6. Many-to-Many Polymorphic Association
In addition to traditional polymorphic associations, you can also define "many-to-many" polymorphic associations. For example, the Post
model and the Video
model can share a polymorphic association to the Tag
model. Using a many-to-many polymorphic association allows you to share a unique list of tags across articles and videos.
More: https://laravel-china.org/doc...
The above is the entire content of this article. I hope it will be helpful to everyone's study. For more related content, please pay attention to PHP Chinese net!
Related recommendations:
Detailed explanation of the responsive interface provided in Laravel 5.5 for responding to requests
About Laravel basic Migrations Analysis
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