在Laravel 5.2中使用雄辩而不是查询

Question

我提出了一个查询，但我并不满意，因为我想用Eloquent来做！

下面是该查询：

Tournament::leftJoin('category_tournament', 'category_tournament.tournament_id', '=', 'tournament.id') 
     ->leftJoin('category_tournament_user', 'category_tournament_user.category_tournament_id', '=', 'category_tournament.id') 
     ->where('category_tournament_user.user_id', '=',$this->id) 
     ->select('tournament.*') 
     ->distinct() 
     ->get(); 

迁移：

Schema::create('tournaments', function(Blueprint $table) { 
    $table->increments('id'); 
    $table->string('name'); 
    $table->timestamps(); 
}); 

Schema::create('categories', function(Blueprint $table) { 
    $table->increments('id'); 
    $table->string('name'); 
    $table->timestamps(); 
}); 

Schema::create('category_tournament', function(Blueprint $table) { 
    $table->increments('id'); 
    $table->integer('category_id'); 
    $table->integer('tournament_id'); 
    $table->timestamps(); 

    $table->foreign('tournament_id') 
      ->references('id') 
      ->on('tournament') 
      ->onDelete('cascade'); 

     $table->foreign('category_id') 
      ->references('id') 
      ->on('category') 
      ->onDelete('cascade'); 
}); 

Schema::create('category_tournament_user', function (Blueprint $table) { 
     $table->increments('id'); 
     $table->integer('category_tournament_id')->unsigned()->index(); 
     $table->foreign('category_tournament_id') 
      ->references('id') 
      ->on('category_tournament') 
      ->onDelete('cascade'); 


     $table->integer('user_id')->unsigned()->index(); 
     $table->foreign('user_id') 
      ->references('id') 
      ->on('users') 
      ->onDelete('cascade'); 

     $table->unique(array('category_tournament_id', 'user_id')); 

     $table->boolean('confirmed'); 

     $table->timestamps(); 
     $table->softDeletes(); 
     $table->engine = 'InnoDB'; 


    }); 

模型

class Tournament extends Model 
{ 
    public function categories() 
    { 
     return $this->belongsToMany(Category::class); 
    } 

    public function categoryTournaments() 
    { 
     return $this->hasMany(CategoryTournament::class); 
    } 
} 

class Category extends Model 
{ 
    public function tournaments() 
    { 
     return $this->belongsToMany(Tournament::class); 
    } 

    public function categoryTournament() 
    { 
     return $this->hasMany(CategoryTournament::class); 
    } 
} 

class CategoryTournament extends Model 
{ 
    protected $table = 'category_tournament'; 

    public function category() 
    { 
     return $this->belongsTo(Category::class); 
    } 

    public function tournament() 
    { 
     return $this->belongsTo(Tournament::class); 
    } 

    public function users() 
    { 
     return $this->belongsToMany(User::class, 'category_tournament_user'); 
    } 
} 

class User extends Authenticatable 
{ 
    public function categoryTournaments() 
    { 
     return $this->belongsToMany(CategoryTournament::class, 'category_tournament_user'); 
    } 
} 

的查询工作，我只是想知道我应该怎么用雄辩这样做是因为我无法自己做：（

任何想法如何做？

Answer 1

首先，你必须外键添加到您的迁移表+，使他们无符号的，因为你可能永远不会有任何负面的ID是非常有用：

$table->integer('tournament_id')->unsigned(); 
$table->foreign('tournament_id')->references('id')->on('tournaments'); 

既然你已经为你的模型中的关系你应该能够使用雄辩来获得内容。

你能坚持到这个页面，进一步了解如何雄辩： https://laravel.com/docs/5.0/eloquent

应该是这样的：

$tournaments = Tournament::with('category_tournament') 
    ->with('category_tournament_user')  
    ->where('category_tournament_user.user_id', '=',$this->id) 
    ->distinct() 
    ->get(); 

您可以使用$比赛内容算账：

$tournaments->category_tournament->name; 

希望我没有错过任何关键的步骤，但我认为它应该通过做这些改变来工作。

编辑：

https://laravel.com/docs/5.1/eloquent-relationships#eager-loading

当访问作为属性口才关系，关系数据是 “延迟加载”。这意味着关系数据在第一次访问该属性之前并未实际加载。但是，Eloquent可以在查询父模型时“加载”关系。急切的加载减轻了N + 1查询问题。要说明N + 1查询问题，请考虑与作者有关​​的Book模型作者：