How flexible use in Laravel in Trait

Laravel / 3 months ago / 1740 / 4 / Updated 3 months ago

Siu Ho @ This is the ninth article

Long time no update articles, and said the result was a good week more time is their own arrangements for the defeated. . . .

Today, we introduce is in Laravel how to use and flexible Trait, talking about Trait , I started not know what kind of existence, there is a vague impression is: reuse. Has always been the understanding of the use and reuse of is this: write in a public class, where the need to call where the purpose is less to write some code, ha ha.

Ado, now.

Foreword

You may often see the following situations:

class Post extends Model
{ protected static function boot() { parent::boot(); static::saving(function ($post){ $post->creator_id = $post->creator_id ?? \auth()->id(); }); } } // 或者 class Video extends Model { protected static function boot() { parent::boot(); static::saving(function ($post){ $post->creator_id = $post->creator_id ?? \auth()->id(); }); } } // 或者直接在控制器中指定 creator_id

We can see, the code is clearly repeated, but in the end how separated achieve reuse it.

such?

public function hasCreator($model) { $model->creator_id = $model->creator_id ?? \auth()->id(); } // 封装一个上述公共方法，然后在模型中调用，或者在控制器中调用。

We found that these operations are not very good, not elegant, ha ha. From the example above Now we look at laravel the Trait how is defined and used:

// 定义

trait HasCreator
{
    public static function bootHasCreator() { static::saving(function ($model) { $model->creator_id = $model->creator_id ?? \auth()->id(); }); } } // 调用 class Post extends Model { use HasCreator; } // 可以了，哈哈，自动调用已经可以实现对 creator_id 的自动写入了，是不是很优雅，哈哈。

Now explain step by step how to write.

Start

The official explanation: Trait is a mechanism for code reuse single inheritance language similar to PHP's prepared. Trait In order to reduce single inheritance language restrictions, allowing developers to freely separate class multiplexing method in a different hierarchy. Trait semantic definitions and combinations of Class A way to reduce complexity, avoid the traditional typical problems and multiple inheritance classes Mixin related. .

First we have to know how to define a Traitkeyword is used trait instead of class
```
namespace App\Traits;

trait HasCreator { } 
```

Define methods (we start with a simple to)

namespace App\Traits;

trait HasCreator { public static function hasCreator() { static::saving(function ($model) { $model->creator_id = $model->creator_id ?? 1; }); } }

It can be seen in Trait the declaration of a setCreator method, which is still there creator to set the default value

transfer

namespace App;

use App\Traits\HasCreator; use Illuminate\Database\Eloquent\Model; use Illuminate\Database\Eloquent\SoftDeletes; class Post extends Model { use HasCreator， SoftDeletes; protected $fillable = ['title', 'user_id']; protected static function boot() { parent::boot(); self::hasCreator(); } }

With my understanding it is to Trait the methods incorporated into the model to go, in order to use it use a bit, and then when as like to call their own declaration.

We can also see the example above use the SoftDeletes , let's simply look at its source code:

namespace Illuminate\Database\Eloquent; trait SoftDeletes { /** * Indicates if the model is currently force deleting. * * @var bool */ protected $forceDeleting = false; /** * Boot the soft deleting trait for a model. * * @return void */ public static function bootSoftDeletes() { static::addGlobalScope(new SoftDeletingScope); } /** * Force a hard delete on a soft deleted model. * * @return bool|null */ public function forceDelete() { $this->forceDeleting = true; return tap($this->delete(), function ($deleted) { $this->forceDeleting = false; if ($deleted) { $this->fireModelEvent('forceDeleted', false); } }); } ...... }

We can see from the source code display, the current Trait definition of a property, two methods can actually define properties, it is not very unexpected, ha ha.

You might ask, if Task also defines the $forceDeleting attributes how to do, which dominated it, there actually has a priority: call the class> Trait> parent, that appeared to duplicate the properties and calling class when Trait in time method, the default is the calling class-based.

Next we look at the following two methods:

bootSoftDeletes: Static prefix plus the boot, which means Shane? It represents the default action, ha ha.

Since it can be defined as an automatic call, we are not the above HasCreator change about it:

    namespace App\Traits;

    trait HasCreator { public static function hasCreator() // -> 改为 bootHasCreator { static::saving(function ($model) { $model->creator_id = $model->creator_id ?? 1; }); } }

It has been invoked automatically, then:

namespace App;

use App\Traits\HasCreator; use Illuminate\Database\Eloquent\Model; use Illuminate\Database\Eloquent\SoftDeletes; class Post extends Model { use HasCreator， SoftDeletes; protected $fillable = ['title', 'user_id']; }

So can you!

That method before and behind hasCreator is the same, as their method calls Jiuhaola, whether declared as static to see their own needs.

Here we recommend some of the projects with the resulting Trait, are plucked from the ultra-brother there, ha ha.

Small Case

HasCreator

Specifies the creator

namespace App\Traits;

use App\User; /** * Trait HasCreator. * * @property \App\User $creator */ trait HasCreator { public static function bootHasCreator() { static::saving(function ($model) { $model->creator_id = $model->creator_id ?? \auth()->id(); }); } /** * @return \Illuminate\Database\Eloquent\Relations\BelongsTo */ public function creator() { return $this->belongsTo(User::class, 'creator_id')->withTrashed(); } /** * @param \App\User|int $user * * @return bool */ public function isCreatedBy($user) { if ($user instanceof User) { $user = $user->id; } return $this->creator_id == \intval($user); } }

Trait Defines three methods, now give you a brief explanation of Kazakhstan:

bootHasCreator: Default given the current authenticated user. As the following static::saving do not understand, before you can see the article clatter.
creator: correlation model definition
isCreatedBy: to determine whether the user is the creator of the incoming current

BelongsToUser

Specifies the user

namespace App\Traits;

use App\User; /** * Trait BelongsToUser. * * @property \App\User $user */ trait BelongsToUser { public static function bootBelongsToUser() { static::creating(function ($model) { if (!$model->user_id) { $model->user_id = \auth()->id(); } }); } /** * @return \Illuminate\Database\Eloquent\Relations\BelongsTo */ public function user() { return $this->belongsTo(User::class)->withTrashed(); } /** * @param \App\User|int $user * * @return bool */ public function isOwnedBy($user) { if ($user instanceof User) { $user = $user->id; } return $this->user_id == \intval($user); } }

I will not explain it, and above is about the same, we see to understand.

Conclusion

It is simple to tell you about Trait in Laravel , write wrong place and how to use the supplement are welcome to leave a message Oh, ha ha.

Related links: "I understand PHP Trait" (deeper explanation of Trait - produced super brother, ha ha), "to grasp the concept and usage of PHP Trait"