Laravel 5框架学习之Eloquent 关系

发布:smiling　来源: PHP粉丝网　添加日期：2021-05-22 13:44:00　浏览: 评论：0　

Eloquent是Laravel的原始ActiveRecord是实现的，建立在Laravel的Fluent Query Builder之上的，所以Eloquent类和Fluent类是一样的，能实现复杂的SQL语句和非常直观表达出的表与表之间的关系

一个用户可能有多个文章，一个文章是某个用户书写的，这就是关系。同样文章中可能包含多个 TAG，而一个 TAG 可能关联多个文章。

在项目中，我们已经有了 User.php，也就是用户模型，查看一下，相当简单。我们希望直接使用 $user->articles() 的形式获取全部文章，让我们修改 user 模型：

public function articles() {

return $this->hasMany('App\Article');

}

但是我们仅仅完成了关系中的一端，让我们来处理另一端。我们希望的形式是 $article->user() ，让我们修改 article 模型。

public function user() {

return $this->belongsTo('App\User');

}

在我们的数据库中，文章模型没有用户的外键，我们需要设置，修改 create_article_table.php

Schema::create('articles', function(Blueprint $table)

{

$table->increments('id');

     //指定外键列

     $table->integer('user_id')->unsigned();

     $table->string('title');

     $table->text('body');

     $table->timestamp('published_at');

$table->timestamps();

     //生成外键

     $table->foreign('user_id')

       ->references('id')

       ->on('users')

       ->onDelete('cascade');

});

因为我们只是在开发阶段，还没有上线运行，我们可以直接修改数据库迁移文件，回滚然后迁移即可，但是如果上线运行的话，应该新建一个迁移。

php artisan migrate:refresh

#输出信息

Rolled back: 2015_03_28_050138_create_article_table

Rolled back: 2014_10_12_100000_create_password_resets_table

Rolled back: 2014_10_12_000000_create_users_table

Nothing to rollback.

Migrated: 2014_10_12_000000_create_users_table

Migrated: 2014_10_12_100000_create_password_resets_table

Migrated: 2015_03_28_050138_create_article_table

Migrated: 2015_03_28_051200_add_excerpt_to_articels_table

现在让我们使用 tinker 来创建一个用户。

php artisan tinker

Psy Shell v0.4.1 (PHP 5.4.16 — cli) by Justin Hileman

#下面是执行过程

>>> $user = new App\User;

=> <App\User #000000007f1ad61a000000006497cc4f> {}

>>> $user->name = 'zhang jinglin';

=> "zhang jinglin"

>>> $user->email = 'zjl@example.com';

=> "zjl@example.com"

>>> $user->password = bcrypt('pass');

=> "$2y$10$Nbl2b9wqd.rXqKEsd3pRSOoIyFAFIhbqf71BufwDfS3Guv21SlEx2"

>>> $user->save();

=> true

>>> App\User::first()->toArray();

=> [

    "id"     => "1",

    "name"    => "zhang jinglin",

    "email"   => "zjl@example.com",

    "created_at" => "2015-03-31 03:24:55",

    "updated_at" => "2015-03-31 03:24:55"

  ]

>>>

现在我们需要新发布的文章和用户关联，我们暂时先修改 form_partial.blade.php 来隐藏一个用户id，只是暂时：

{{--临时处理--}}

{!! Form::hidden('user_id', 1) !!}

同时要修改模型的 $fillabel 属性，以便我们的 Mass Assisment。

protected $fillable = [

   'title',

   'body',

   'published_at',

   'user_id' //临时设置

];

OK，添加一个文章。我们使用 tinker 来查看一下。

php artisan tinker

Psy Shell v0.4.1 (PHP 5.4.16 — cli) by Justin Hileman

>>> App\Article::first()->toArray();

=> [

    "id"      => "1",

    "user_id"   => "1",

    "title"    => "User 1 Article",

    "body"     => "User 1 Body",

    "published_at" => "2015-03-31 08:00:00",

    "created_at"  => "2015-03-31 04:17:58",

    "updated_at"  => "2015-03-31 04:17:58",

    "excerpt"   => null

  ]

#获取用户

>>> $user = App\User::first();

=> <App\User #0000000051cbb9d70000000073e11a3e> {

    id: "1",

    name: "zhang jinglin",

    email: "zjl@example.com",

    created_at: "2015-03-31 03:24:55",

    updated_at: "2015-03-31 03:24:55"

  }

#获取用户文章

>>> $user->articles()->toArray();

BadMethodCallException with message 'Call to undefined method Illuminate\Database\Query\Builder::toArray()'

>>> $user->articles->toArray();

=> [

    [

      "id"      => "1",

      "user_id"   => "1",

      "title"    => "User 1 Article",

      "body"     => "User 1 Body",

      "published_at" => "2015-03-31 08:00:00",

      "created_at"  => "2015-03-31 04:17:58",

      "updated_at"  => "2015-03-31 04:17:58",

      "excerpt"   => null

    ]

  ]



#为什么使用 $user->articles 而不是 #user->articles()?

#事实上，$user->articles()返回的是关系，如果你想用 articles() 你需要这样用

>>> $user->articles()->get()->toArray();

=> [

    [

      "id"      => "1",

      "user_id"   => "1",

      "title"    => "User 1 Article",

      "body"     => "User 1 Body",

      "published_at" => "2015-03-31 08:00:00",

      "created_at"  => "2015-03-31 04:17:58",

      "updated_at"  => "2015-03-31 04:17:58",

      "excerpt"   => null

    ]

  ]



#你只能使用 articles() 来进行下一步的工作，比如下面的查询

$user->articles()->where('title', 'User 1 Article')->get();

#我们也可以通过 article 获取 user

>>> $article = App\Article::first();

=> <App\Article #0000000051cbb9d60000000073e11a3e> {

    id: "1",

    user_id: "1",

    title: "User 1 Article",

    body: "User 1 Body",

    published_at: "2015-03-31 08:00:00",

    created_at: "2015-03-31 04:17:58",

    updated_at: "2015-03-31 04:17:58",

    excerpt: null

  }

>>> $article->user;

=> <App\User #0000000051cbb92d0000000073e11a3e> {

    id: "1",

    name: "zhang jinglin",

    email: "zjl@example.com",

    created_at: "2015-03-31 03:24:55",

    updated_at: "2015-03-31 03:24:55"

  }

>>>