在雄辩模型的构造函数中创建一个作为类变量的闭包

Question

I'm trying to create a lambda-style closure as a dynamically-named class variable, within the constructor of an Eloquent model.

It's working fine when the object is instantiated except for when creating a model (that is to say, read, update, and delete work fine).

I can get around the problem by explicitly declaring the class variable prior to instantiating the object, however, this is just a hack, I need to be able to create class variables (as closures) dynamically.

The following code works, but fails if I remove the declaration $public foo;

public $foo;
public function __construct() {
    $foo = 'foo';
    $this->{$foo} = function ($args) { return 'foo';};
}

I'm getting the following error:

exception 'ErrorException' with message 'Object of class Closure could not be converted to string' in /Users/Sites/.../vendor/laravel/framework/src/Illuminate/Support/helpers.php:900

Like I mentioned, this only occurs when creating/inserting an object (sorry if that sounds vague but anyone familiar with Laravel should know what I mean)... instantiating a model in other circumstances (read/update/delete) works just fine. Any ideas as to what might be causing the problem would be greatly appreciated!

Answer 1

Override setAttribute and getAttribute on your model:

protected $closures = [];

public function setAttribute($key, $value)
{
    if ($value instanceof \Closure)
    {
        $this->setClosureProperty($key, $value);
    }

    parent::setAttribute($key, $value);
}

public function getAttribute($key)
{
    if (array_key_exists($key, $this->closures)
    {
        return $this->closures[$key];
    }

    return parent::getAttribute($key);
}

public function setClosureProperty($key, \Closure $value)
{
    $this->closures[$key] = $value;
}

This way the cloures won't be saved in the attributes array, thus won't be saved and cast to string.