Laravel多个属性级别

In my model, I have an attribute 'data' saved as type json. When I access this attribute, I want to json_decode it and create an attribute for each keys. This part work fine

protected $dataAttribute = array('uiSearch');

public function getDataAttribute($value)
{
    $json = json_decode($value,true);

    $object = new stdClass;

    foreach($this->dataAttribute as $attribute)
    {
        $this->data->attributes[$attribute] = '';
        $object->{$attribute} = '';
    }

    if($json)
    {
        foreach($json as $key => $data)
        {
            if(property_exists($object, $key))
            {
                $this->data->attributes[$key] = $data;
                $object->{$key} = $data;
            }
        }
    }
    return $object;
}

I can now access it like this

$model->data->uiSearch

I want to be able to set value of each new attributes and when I save the model, its goes back into json.

public function setDataAttribute($value)
    {
        $json = array();

        foreach($this->dataAttribute as $attribute)
        {
            $json[$attribute] = '';
        }

        foreach($value as $key => $data)
        {
            if(isset($json[$key]))
            {
                $json[$key] = $data;
            }
        }

        $this->attributes['data'] = json_encode($json);
    }

Not working

$model->data->uiSearch = "test";

I tried to override eloquent saving method

 public static function boot()
    {
        if(_B2B && Auth::check() && !defined('_INSURANCE'))
        {
            parent::boot();

            static::saving(function($post)
            {
                // My attribute is empty
                Log::error(print_r($post->data,true));
            });
        }
    }