Laravel Eloquent Serialization: how to rename property?

I do it in this way.

protected $remap_attrs = ['old_name' => 'new_name'];
public function toArray(){
    $array = parent::toArray();
    foreach($this->remap_attrs as $key => $new_key) {
        if(array_key_exists($key, $array)) {
            $array[$new_key] = $array[$key];
            unset($array[$key]);
        }
    }
    return $array;
}

Add single "aliases" using attribute accessors

You can use attribute accessors to create "new attributes":

public function getUserIdAttribute(){
    return $this->attributes['user_id'];
}

This allows you to access the value this way: $user->userId

Now let's add the value to array / JSON conversion:

protected $appends = array('userId');

And finally hide the ugly user_id:

protected $hidden = array('user_id');

Convert all attribute names when converting to array / JSON

You can also use toArray() to change the all attribute names when converting the model into an array or JSON string.

public function toArray(){
    $array = parent::toArray();
    $camelArray = array();
    foreach($array as $name => $value){
        $camelArray[camel_case($name)] = $value;
    }
    return $camelArray;
}