How to set a default attribute value for a Laravel

问题:

If I try declaring a property, like this:

public $quantity = 9;

...it doesn't work, because it is not considered an "attribute", but merely a property of the model class. Not only this, but also I am blocking access to the actually real and existent "quantity" attribute.

What should I do, then?

回答1:

An update to this...

@j-bruni submitted a proposal and Laravel 4.0.x is now supporting using the following:

protected $attributes = array(
  'subject' => 'A Post'
);

Which will automatically set your attribute subject to A Post when you construct. You do not need to use the custom constructor he has mentioned in his answer.

However, if you do end up using the constructor like he has (which I needed to do in order to use Carbon::now()) be careful that $this->setRawAttributes() will override whatever you have set using the $attributes array above. For example:

protected $attributes = array(
  'subject' => 'A Post'
);

public function __construct(array $attributes = array())
{
    $this->setRawAttributes(array(
      'end_date' => Carbon::now()->addDays(10)
    ), true);
    parent::__construct($attributes);
}

// Values after calling `new ModelName`

$model->subject; // null
$model->end_date; // Carbon date object

// To fix, be sure to `array_merge` previous values
public function __construct(array $attributes = array())
{
    $this->setRawAttributes(array_merge($this->attributes, array(
      'end_date' => Carbon::now()->addDays(10)
    )), true);
    parent::__construct($attributes);
}

See the Github thread for more info.

回答2:

This is what I'm doing now:

protected $defaults = array(
   'quantity' => 9,
);

public function __construct(array $attributes = array())
{
    $this->setRawAttributes($this->defaults, true);
    parent::__construct($attributes);
}

I will suggest this as a PR so we don't need to declare this constructor at every Model, and can easily apply by simply declaring the $defaults array in our models...

---

UPDATE:

As pointed by cmfolio, the actual ANSWER is quite simple:

Just override the $attributes property! Like this:

protected $attributes = array(
   'quantity' => 9,
);

The issue was discussed here.

回答3:

I know this is really old, but I just had this issue and was able to resolve this using this site.

Add this code to your model

protected static function boot()
{
   parent::boot();

   static::creating(function ($model) {
        $model->user_id = auth()->id();
    });
}

Update/Disclaimer

This code works, but it will override the regular Eloquent Model creating Event