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[Expression Language] Null coalescing operator doesn't work? #54359

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adamkiss opened this issue Mar 21, 2024 · 6 comments · May be fixed by #54757
Closed

[Expression Language] Null coalescing operator doesn't work? #54359

adamkiss opened this issue Mar 21, 2024 · 6 comments · May be fixed by #54757
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Bug ExpressionLanguage Status: Needs Review Status: Waiting feedback

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@adamkiss
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adamkiss commented Mar 21, 2024 •
edited

Symfony version(s) affected

7.0

Description

According to docs, we can use null-coalescing operator to provide fallback to potentially empty or even nonexistent variables. However I can't make it work, even in a simple file with nothing but Expression Language.

How to reproduce

$lang = new ExpressionLanguage();

$data = [
    'exists' => true,
];

$expression1 = 'notexists ?? "nope,"';
$expression2 = '(notexists ?? "nope,")';
$expression3 = '(notexists ?? false) ? "yes" : "no"';

foreach ([$expression1, $expression2, $expression3] as $exp) {
    try {
        var_dump($lang->evaluate($exp, $data));
    } catch (\Throwable $th) {
        echo('!');
    }
}
// expected: nope,nope,no
// actual: !!!

(In the reproduction I have suppressed the throws, but every evaluate fails with Fatal error: Uncaught Symfony\Component\ExpressionLanguage\SyntaxError: Variable "notexists" is not valid around position …

Possible Solution

No response

Additional Context

No response
@adamkiss adamkiss added the Bug label Mar 21, 2024
@MatTheCat
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The problem is not the operator but the fact you cannot reference variables you haven’t passed in an expression. What is your use-case for doing so?

@adamkiss
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adamkiss commented Mar 21, 2024 •
edited

@MatTheCat Acting on a variable hashmap

If it's not possible, I'll understand, but docs specifically mention this usecase: https://symfony.com/doc/current/components/expression_language.html#null-coalescing-operator

Right first example is foo ?? "no", and the null-coalescing description is

It returns the left hand-side if it exists and it's not null; otherwise it returns the right hand-side.

(emphasis mine)

@MatTheCat
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Indeed, but looking at the code it seems this use-case was never intended (the example will only work if foo is null) 🤔

Maybe you could open an issue in symfony-docs? It seems also weird to have the null-coalescing operator documented here instead of here.

@adamkiss
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@MatTheCat I'm not using it as a part of Symfony, so I wasn't sure where to post it; Will post it in docs

@adamkiss adamkiss mentioned this issue Mar 21, 2024
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@xabbuh
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xabbuh commented Mar 21, 2024

closing in favour of the docs issue

@xabbuh xabbuh closed this as not planned Won't fix, can't repro, duplicate, stale Mar 21, 2024
@adamkiss
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@xabbuh I hoped for "that should work" tbh 😂

@adamkiss adamkiss mentioned this issue Apr 28, 2024
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Labels
Bug ExpressionLanguage Status: Needs Review Status: Waiting feedback
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[ExpressionLanguage] Support non-existent names when followed by null coalescing adamkiss/symfony
4 participants
@adamkiss @MatTheCat @xabbuh @carsonbot