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Allow AbstractNormalizer to use null for nullable constructor parameters without default value #40511

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pounard opened this issue Mar 18, 2021 · 3 comments · Fixed by #40522
Closed

Allow AbstractNormalizer to use null for nullable constructor parameters without default value #40511

pounard opened this issue Mar 18, 2021 · 3 comments · Fixed by #40522
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Bug Serializer Status: Needs Review

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@pounard
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pounard commented Mar 18, 2021 •
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Symfony version(s) affected: All versions until 5.1 (but I guess 5.2 is too)

Description

Serializer component AbstractNormalizer attemps to guess constructor parameters, and falls back using default values when possible, which is good. Yet, it misses one use case: when you specify nullable non-optional parameter, case in which null is a valid value, not the default one, yet still valid.

It's a matter a choice, either we consider that the incoming data should explicitly set null here, or we consider that it might come from a dynamic language such as JavaScript that may remove undefined values from sent JSON: case in which we might want to fix that and consider that undefined is null.

How to reproduce

Simply write a class with a constructor as such:

class Foo
{
    public function __construct(string $foo, ?string $bar)
    {
    }
}

And attempt to denormalize using this incoming array:

$input = [
    'foo' => 'any value',
];

In this specific case, null is an allowed value for $bar, and value is not set in $input, why not simply give it null ? Actual behaviour is that the exception for missing constructor argument is raised and prevents the object from being denormalized.

Possible Solution

Easy two-line fix, in AbstractNormalizer::instantiateObject() as such:

Replace:

                } elseif (\array_key_exists($key, $this->defaultContext[self::DEFAULT_CONSTRUCTOR_ARGUMENTS][$class] ?? [])) {
                    $params[] = $this->defaultContext[self::DEFAULT_CONSTRUCTOR_ARGUMENTS][$class][$key];
                } elseif ($constructorParameter->isDefaultValueAvailable()) {
                    $params[] = $constructorParameter->getDefaultValue();
                } else {
                    throw new MissingConstructorArgumentsException(sprintf('Cannot create an instance of "%s" from serialized data because its constructor requires parameter "%s" to be present.', $class, $constructorParameter->name));
                }

Using:

                } elseif (\array_key_exists($key, $this->defaultContext[self::DEFAULT_CONSTRUCTOR_ARGUMENTS][$class] ?? [])) {
                    $params[] = $this->defaultContext[self::DEFAULT_CONSTRUCTOR_ARGUMENTS][$class][$key];
                } elseif ($constructorParameter->isDefaultValueAvailable()) {
                    $params[] = $constructorParameter->getDefaultValue();
                } elseif ($constructorParameter->hasType() && $constructorParameter->getType()->allowsNull()) {
                    $params[] = null;
                } else {
                    throw new MissingConstructorArgumentsException(sprintf('Cannot create an instance of "%s" from serialized data because its constructor requires parameter "%s" to be present.', $class, $constructorParameter->name));
                }

I just added those two lines:

                } elseif ($constructorParameter->hasType() && $constructorParameter->getType()->allowsNull()) {
                    $params[] = null;

Compatible for all PHP version from 7.0 if I read correctly https://www.php.net/manual/en/reflectiontype.allowsnull.php
@pounard pounard added the Bug label Mar 18, 2021
@pounard
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pounard commented Mar 18, 2021 •
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I'm sorry if I misclassified this, it could be either a bug or a feature request, in my opinion it's a bug, but it would be legit for you to downgrade to a feature request.

I have no strong feeling about this, but since there's no easy other workaround than writing a custom normalizer for each class (and I basically have hundreds that matches this behaviour in my current project) then I consider the fact that working around being not easy as a bug :)

@pounard
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pounard commented Mar 19, 2021

OK, I see that @ro0NL seems to like the idea, I'll try to add a PR within the week, as always, lot of work to do, not much spare time for open source :/

pounard added a commit to pounard/symfony that referenced this issue Mar 19, 2021
@pounard
issue symfony#40511 - AbstractNormalizer force null for non-optional …
e373e77 
…nullable constructor parameter denormalization when not present in input
@pounard pounard mentioned this issue Mar 19, 2021
Merged
pounard added a commit to pounard/symfony that referenced this issue Mar 22, 2021
@pounard
issue symfony#40511 - AbstractNormalizer force null for non-optional …
2dc3e97 
…nullable constructor parameter denormalization when not present in input
@chalasr chalasr closed this as completed Mar 29, 2021
chalasr added a commit that referenced this issue Mar 29, 2021
@chalasr
bug #40522 [Serializer] Allow AbstractNormalizer to use null for non-…
e16be83 
…optional nullable constructor parameters without default value (Pierre Rineau)

This PR was merged into the 4.4 branch.

Discussion
----------

[Serializer] Allow AbstractNormalizer to use null for non-optional nullable constructor parameters without default value

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | Fix #40511
| License       | MIT

Serializer component AbstractNormalizer attemps to guess constructor parameters, and falls back using default values when possible. Yet, it misses one use case: nullable non-optional parameter with value not being present in incoming input, case in which null is a valid value, not the default one, yet still valid.

This PR introduce a two-line fix that forcefully set null as value for missing from input non-optional nullable constructor parameters values.

Commits
-------

d29e433 [Serializer] AbstractNormalizer force null for non-optional nullable constructor parameter denormalization when not present in input
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@pounard @xabbuh @chalasr @carsonbot