Laravel 5框架学习之Eloquent 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('AppArticle');    }  

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('AppUser');    }  

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 AppUser;  => <AppUser #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  >>> AppUser::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  >>> AppArticle::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 = AppUser::first();  => <AppUser #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 IlluminateDatabaseQueryBuilder::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 = AppArticle::first();  => <AppArticle #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;  => <AppUser #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"    }  >>>   

以上所述就是本文的全部内容了,希望大家能够喜欢。

Laravel 5框架学习之Eloquent 关系

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