Analysis of Laravel's Eloquent ORM

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Release： 2023-04-02 22:04:01

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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

Analysis of Laravels Eloquent ORM

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

Analysis of Laravels Eloquent ORM

1.2 调试工具 Laravel Debugbar

https://github.com/barryvdh/l...

Installation：

composer require barryvdh/laravel-debugbar --dev

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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();
        });
    }

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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);
}

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2.2.2 反向关系绑定

public function user()
{
    return $this->belongsTo(User::class);
}

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2.3 外键

Analysis of Laravels Eloquent ORM

自定义外键：

return $this->hasOne(Profile::class,'显示指定自定义外键');

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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);
});

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三、一对多关系映射

Analysis of Laravels Eloquent ORM

1:N hasMany(XXX:class) 

反之：belongsTo(XXX:class)

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Analysis of Laravels Eloquent ORM

3.1 面向对象方式绑定一对多的关系

Analysis of Laravels Eloquent ORM

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);
}

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4.1 面向对象方式绑定多对多的关系

Analysis of Laravels Eloquent ORM

detach解绑，sync方法用的比较多，只保留1，2
Analysis of Laravels Eloquent ORM

4.2 访问多对多中间数据表

Analysis of Laravels Eloquent ORM

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

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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);
    }
}

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$factory->define(App\Paper::class, function (Faker $faker) {
    return [
        'title' => $faker->sentence,
        'user_id' => \App\User::all()->random()->id,
    ];
});

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Analysis of Laravels Eloquent ORM

$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),
    ];
});

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Analysis of Laravels Eloquent ORM

获取每个国家论文总数：

Analysis of Laravels Eloquent ORM

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

Analysis of Laravels Eloquent ORM

更多：https://laravel-china.org/doc...
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Analysis of Laravels Eloquent ORM

Analysis of Laravels Eloquent ORM

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...

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