Create new Object by string variable in Symfony3/PHP

Question

I send variables to my route via an ajax post. Based on the value of my type value I create a new Object, like this:

if($request->get('type') === 'HardwareType'){
    $e = new HardwareType();
}else if($request->get('type') === 'SetupType'){
    $e => new SetupType();
}else{
    new NotFoundHttpException();
}

This gets out of hand quickly even with a switch I think its still "ugly". Is there any way I could do sth. like this:

$e = new $request->get('type')();

Any hint appreciated

EDIT I use the class(es) with this use AppBundle\Entity\HardwareType; etc.

Why not use a container, each class(or service, or whatever) can have an alias. Instead of doing new HardwareType you can use $container->get('class_service_whatever_id);` — Andrei
– Andrei, Commented Sep 19, 2017 at 13:49

Alessandro Minoccheri · Accepted Answer · 2017-09-19 13:43:29Z

3

you can do this:

$e = $request->get('type');
$class = new $e();

If you need you can add the path or the class like this:

$e = 'AppBundle\Entity\' . $request->get('type');

Obviously you need to add use at the begin of the file and you can check before the new if the class exist or not

Like this:

if (!class_exists($e)) {
   //exception
}

edited Sep 19, 2017 at 13:43

answered Sep 19, 2017 at 13:37

Alessandro Minoccheri

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10 Comments

delboy1978uk Over a year ago

That has potential to fail without any checks

Pieter van den Ham Over a year ago

Hackers would love this in combination with a vulnerable Composer library

delboy1978uk Over a year ago

@Pete IKR? More strictness required!

PrimuS Over a year ago

Thanks for the concerns, it's an internal project only with no intention to ever go public. However, is there a safe approach? It worked btw. like a charm so I will accept this in any case! Thank you

Daniel Over a year ago

Take a look into the factory-pattern, maybe this is what you need.

|

delboy1978uk · Accepted Answer · 2017-09-19 13:46:33Z

2

Just use an associative array! Define the acceptable classes, so that other types of class you don't want to allow can't be instantiated!

Then just check the key is in the array, and if so create a new Whatever()!

$types = [
    'HardwareType' => HardwareType::class,
    'etc' => SomeOther::class
];

$getVar = $request->get('type');

// So all you need do is 
if (array_key_exists($getVar, $types)) {
    $e = new $types[$getVar]();
} else {
    throw new NotFoundHttpException();
}

edited Sep 19, 2017 at 13:46

answered Sep 19, 2017 at 13:40

delboy1978uk

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