[Types] Add JsonDecodeDynamicReturnTypeExtension

[TomasVotruba]

By default, the Nette\Utils\Json::decode() returns mixed, but in some cases we know there is more specific type.

We use this extension internally in private project to separate at array and stdClass, e.g.:

$values = Nette\Utils\Json::decode($values);
echo $values['item'];
// not possible - a stdClass type given

$values = Nette\Utils\Json::decode($values, Nette\Utils\Json::FORCE_ARRAY);
echo $values->item ;
// not possible - an array type given

It might be useful to have in Nette extension itself. What do you think?

cc @staabm @lulco @matthiasnoback

Based on https://twitter.com/VotrubaT/status/1487434178757074952

[TomasVotruba]

2nd arg of json_decode() takes different types in PHP 7.1 and PHP 7.2+

[ondrejmirtes]

What I'd like to see instead is to have this kind of logic for json_decode in phpstan-src. When that's done, this Nette extension can simply delegate the logic with $scope->getType(new FuncCall('json_decode', $args)). Of course $args would be composed based on the FORCE_ARRAY argument so that json_decode is called with $associative=true.

[TomasVotruba]

I actually tried to add function extension first but PHPStan analysed only non-basic function. Not sure why.

Apart that, is the type resolution in tests here correct?

[ondrejmirtes]

Instead of the whole resolveConstantStringType method you just should call this class https://github.com/phpstan/phpstan-src/blob/master/src/Type/ConstantTypeHelper.php, otherwise it looks fine.

[ondrejmirtes]

It can still be an array here.

[TomasVotruba]

On what input?

[staabm]

I guess the stdclass could contain a array of other things?

[ondrejmirtes]

You don't have to guess: https://3v4l.org/qsjVh

BTW I worry that these precise types would become really annoying. Right now people working with json_decode() get some errors on level 9, but with these union types it would be much sonner - on level 7. I think the best course of action is to return "MixedType without stdClass" with FORCE_ARRAY, and normal "MixedType" without FORCE_ARRAY.

MixedType is subtractable - new MixedType(true, new ObjectType(\stdClass::class)) means mixed without stdClass.

[TomasVotruba]

MixedType is subtractable

Cool, that's a new trick to me.

---

I think the best course of action is to return "MixedType without stdClass" with FORCE_ARRAY, and normal "MixedType" without FORCE_ARRAY.

Do you mean like this?

if ($isForceArray) {
    return new MixedType(true, new ObjectType(\stdClass::class));
}

return new MixedType(true);

It might be change with more strict approach, but it would be more correct. The reason we made this extension for our project is to make sure there is only scalar value or stdClass. Mixed includes anything, objects, array of object etc.

Yet the DX is important, I understand. It might be useful to enable this only since level 9+.

[ondrejmirtes]

Just to reiterate - I still want this to be submitted as a json_decode extension to phpstan-src first. Then we can continue here, keep all the tests but make the extension implementation much simpler, delegating to json_decode logic.

[TomasVotruba]

@ondrejmirtes I understand that, I just want to make it work and confirm here, so we don't jump back and forth.
Then function extension port to core and update here.

[TomasVotruba]

@ondrejmirtes As for json_decode, is FunctionTypeSpecifyingExtension the right interface to implement?

[ondrejmirtes]

No (https://phpstan.org/developing-extensions/dynamic-return-type-extensions):

functions using DynamicFunctionReturnTypeExtension interface and phpstan.broker.dynamicFunctionReturnTypeExtension service tag.

[TomasVotruba]

@ondrejmirtes Thanks 👍

I'm trying to add JsonDecodeDynamicReturnTypeExtension, but the only function that is found is PHPStan\Testing\assertType.
The json_decode is never passed.

What I'm doing wrong there?

[TomasVotruba]

Here the json_decode is never passed :/

[TomasVotruba]

To reproduce localy, run PHPUnit:

vendor/bin/phpunit tests/Type/Php/JsonDecodeDynamicReturnTypeExtensionTest.php

↓

[ondrejmirtes]

Because there's already JsonThrowOnErrorDynamicReturnTypeExtension in phpstan-src whcih changes the result based on JSON_THROW_ON_ERROR. You need to modify it first.

[TomasVotruba]

I'll try it