Laravel ::__construct() must implement interface

Question

I'm using Laravel 5.4 And I'm trying to inject a $order class into a trait that's going to implemented by a model. Like this:

class Forum extends Model
{
    use Orderable;

The constructor of the trait looks like this:

trait Orderable
{
    public $orderInfo;

    public function __construct(OrderInterface $orderInfo)
    {
        $this->orderInfo = $orderInfo;
    }

My service provider looks like this:

public function register()
{
    $this->app->bind(OrderInterface::class, function () {
        return new Order(new OrderRepository());
    });

    $this->app->bind(OrderRepositoryInterface::class, function () {
        return new OrderRepository();
    });
}

The constructor of my Order class looks like this:

public function __construct(OrderRepositoryInterface $orderInfo)
{
    $this->orderInfo = $orderInfo;
}

But I receive the error:

Type error: Argument 1 passed to App\Forum::__construct() must implement interface Project\name\OrderInterface, array given, called in /home/vagrant/Code/Package/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php on line 268

The OrderRepository class is implementing the OrderRepositoryInterface. The Order class is implementing the OrderInterface interface.

App\Forum is the model that uses the Orderable trait.

What could I be doing wrong here?

So while calling app->bind( the error shows up, here you have to dig in. Class declaration seems right. Or is something wrong with this statement: must implement interface Project\name\OrderInterface Is the namespace fully right? — JustOnUnderMillions
– JustOnUnderMillions, Commented Mar 7, 2017 at 12:47
Under witch fully namespace is the trait Orderable? -- forget this. You have to check the use of namespaces. Do check declared classes with var_dump(get_declared_classes()); at the end of a script. — JustOnUnderMillions
– JustOnUnderMillions, Commented Mar 7, 2017 at 12:49

Björn · Accepted Answer · 2017-03-07 13:19:51Z

1

You are extending Model. This class already has a __construct that you need to use. This __construct expects array $attributes = [] as the first argument.

So in your __construct you also need to have this as the first argument and pass this to the parent class:

public function __construct(array $attributes = [], OrderRepositoryInterface $orderInfo)
{
    $this->orderInfo = $orderInfo;
    parent::__construct($attributes);
}

However you can work around using __construct in laravel using boot.

For example in a Model:

class Forum extends Model
{
    protected static function boot()
    {
        parent::boot();
        // Do something
    }
}

Or in a Trait:

trait Orderable
{
    public static function bootOrderableTrait()
    {
        static::created(function($item){
            // Do something
        });
    }
}

edited Mar 7, 2017 at 13:19

answered Mar 7, 2017 at 12:59

Björn

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4 Comments

Jenssen Over a year ago

Thanks that makes sense. But then I receive:

Type error: Too few arguments to function App\Forum::__construct(), 1 passed in /home/vagrant/Code/Package/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php on line 268 and exactly 2 expected

any idea?

Björn Over a year ago

What happens if you change your it to: __construct(array $attributes = [], OrderRepositoryInterface $orderInfo = null)

Björn Over a year ago

I updated my answer with a way to use boot instead of __construct

Jenssen Over a year ago

If I make it = null it does not crash anymore. But then is $orderInfo empty. With your bootOrderableTrait example where/how do I instantiate the OrderRepositoryInterface that's being bound to OrderRepository class?

Vitalii Kyrychenko · Accepted Answer · 2017-03-07 12:55:17Z

0

In PHP it's not possible to have multiple constructors. If you will look to Model:

public function __construct(array $attributes = [])

it expect array. That's why I assume that somewhere in Model array passed to constructor instead of 'OrderInterface'.

answered Mar 7, 2017 at 12:55

Vitalii Kyrychenko

3313 silver badges5 bronze badges

2 Comments

Jenssen Over a year ago

So what I'm trying is not possible?

Vitalii Kyrychenko Over a year ago

Maybe it's better to add setter method instead of overriding constructor in trait. Or extend class and override constructor there

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