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_tableRolled back: 2014_10_12_100000_create_passWord_resets_tableRolled back: 2014_10_12_000000_create_users_tableNothing to rollback.Migrated: 2014_10_12_000000_create_users_tableMigrated: 2014_10_12_100000_create_password_resets_tableMigrated: 2015_03_28_050138_create_article_tableMigrated: 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 tinkerPsy 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 = '[email protected]';=> "[email protected]">>> $user->password = bcrypt('pass');=> "$2y$10$Nbl2b9wqd.rXqKEsd3pRSOoIyFAFIhbqf71BufwDfS3Guv21SlEx2">>> $user->save();=> true>>> App\User::first()->toArray();=> [       "id"         => "1",       "name"       => "zhang jinglin",       "email"      => "[email protected]",       "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 tinkerPsy 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: "[email protected]",       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: "[email protected]",       created_at: "2015-03-31 03:24:55",       updated_at: "2015-03-31 03:24:55"   }>>>