Use the creating, updating or saving model events to loop trough your attributes property to set fields to null.

class Model extends \Eloquent {
    public static function boot() {
        parent::boot();

        static::creating(function($model){
            foreach ($model->attributes as $key => $value) {
                $model->{$key} = empty($value) ? null : $value;
            }
        });
    }
}

Thnx! Weird thing is that i still get: SQLSTATE[HY000]: General error: 1366 Incorrect decimal value: '' for column 'sending_cost_netherlands' at row 1

This is working fine:

public function setSendingCostNetherlandsAttribute($value)
{
    if(empty($value)){
        exit;
    }
}

Solution for me:

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

    static::creating(function($model){
        foreach ($model->attributes as $key => $value) {
            $model->{$key} = empty($value) ? null : $value;
        }
    });

    static::updating(function($model){
        foreach ($model->attributes as $key => $value) {
            $model->{$key} = empty($value) ? null : $value;
        }
    });

}

Use saving if you are going to use it both for creating and updating. That way you only need one method instead of two.

@Marwelln,

I have only one strange thing with this piece of code:

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

    static::saving(function($model){
        foreach ($model->attributes as $key => $value) {
            if($value !== 0) {
            $model->{$key} = empty($value) ? null : $value;
            }
        }
    });
}

This piece of code getting called two times when saving a model:

public function setPaymentWaysAttribute($value)
{
    if($value) {
        $value = explode(',', $value);
        $this->attributes['payment_ways'] = serialize($value);
    } else {
        $this->attributes['payment_ways'] = null;
    }
}

So need to make again a fix for this field and also for checkboxes:

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

    static::saving(function($model){
        foreach ($model->attributes as $key => $value) {
            if($value !== 0 AND $key != 'payment_ways') {
            $model->{$key} = empty($value) ? null : $value;
            }
        }
    });
}

A lot of fixing things, for just setting empty fields in the database with the value NULL.

Or you can use setPropertyAttribute($value) to set null

how about setting your mysql table's column default value to null, and making it nullable making it consistent

Nice - handy solution. I needed to make emails on a table unique (and so had a unique index) but also optional. This meant all empty emails had to be saved as a NULL rather than an empty string "". Handing it in the saving event means that it makes no difference how or where the email is set, its mapping to a NULL is safeguarded at a low level in eloquent.

public function create(CarsRequest $request){

    //array_filter setting empty field to null
    $inputs = array_filter($request->all(), 'strlen');

    Car::create($inputs);

    $request->session()->flash('alert-success', 'Car created with success.');

    return redirect()->action('CarController@index');
}