How to use Assert\When in array data validation #49112

QuietNoise · 2023-01-26T07:02:29Z

QuietNoise
Jan 26, 2023

I'm validating contents of an associative array and I can't figure out how to access values of other fields in Assert\When expression.
See the simplified example below. I need validate blob only when hasBlob is set to true.
I'm trying to figure out how to access value hasBlob from within the When expression.
Apparently this.hasBlob won't work because I don't validate object and this is null. And I can't use 'expression' => 'value because value has value of the blob and there is no access to other fields.
I would appreciate if someone can point me in the right direction.

Note: Keep in mind that I'm using Assert\Collection data structure for contraints here rather than hardcoding constraints class because fields and their constraints will be determined during runtime. For simplicity I just show one of the most basic scenarios.

<?php
namespace Example;

use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\Validator\ConstraintViolation;
use Symfony\Component\Validator\Validation;


$data = [
            'title' => 'Oz',
            'hasBlob' => true,
            'blob' => ''
        ];

$constraints = new Assert\Collection([
    'fields' => [
        'title' => [
            new Assert\Type('string'),
            new Assert\Length(['min' => 0, 'max' => 100]),
        ],
        'hasBlob' => [
            new Assert\Type('boolean')
        ],
        'blob' => [
            new Assert\When([                
                'expression' => 'this.hasBlob === true',
                'constraints' => [
                    new Assert\NotBlank(),
                    new Assert\Type('string'),
                    new Assert\Length(['min' => 1, 'max' => 1000]),
                ],
            ])
        ]
    ]
]);

$validator = Validation::createValidator();

$violations = $validator->validate($data, $constraints);
var_dump($violations);

Answered by MatTheCat

Jan 26, 2023

Oh this is weird, this comes from the context’s object, so if there is no object (like in your case) you get null. I’ll dig into this but in the meantime you can use a Callback constraint to validate the field based on others:

'blob' => [
    new Assert\Callback(static function (mixed $blob, ExecutionContextInterface $context): void
    {
        $root = $context->getRoot();
        if (!$root['hasBlob']) {
            return;
        }

        $context->getValidator()->inContext($context)->validate($blob, [
            new Assert\NotBlank(),
            new Assert\Type('string'),
            new Assert\Length(['min' => 1, 'max' => 1000]),
        ]);
    })
]

Also note that hasBlob can …

View full answer

MatTheCat · 2023-01-26T09:14:00Z

MatTheCat
Jan 26, 2023

Oh this is weird, this comes from the context’s object, so if there is no object (like in your case) you get null. I’ll dig into this but in the meantime you can use a Callback constraint to validate the field based on others:

'blob' => [
    new Assert\Callback(static function (mixed $blob, ExecutionContextInterface $context): void
    {
        $root = $context->getRoot();
        if (!$root['hasBlob']) {
            return;
        }

        $context->getValidator()->inContext($context)->validate($blob, [
            new Assert\NotBlank(),
            new Assert\Type('string'),
            new Assert\Length(['min' => 1, 'max' => 1000]),
        ]);
    })
]

Also note that hasBlob can be computed from blob so maybe you don’t even need all of this.

2 replies

MatTheCat Jan 26, 2023

In fact When has a $values parameter you can use to inject variables in the expression:

'blob' => [
    new Assert\When([
         'expression' => 'hasBlob === true',
         'constraints' => [
            new Assert\NotBlank(),
            new Assert\Type('string'),
            new Assert\Length(['min' => 1, 'max' => 1000]),
        ],
        'values' => ['hasBlob' => $data['hasBlob']]
    ])
]

Still,

note that hasBlob can be computed from blob so maybe you don’t even need all of this.

QuietNoise Jan 26, 2023
Author

Thank you,
The reason I want use When is because the code is much more readable. I played with injection just now and I believe this is the most elegant way to do it for now.
While I can compute hasBlob from blob itselt in the example above this is just a simplified example.
In real life I need compute more complex conditions and based on that decide format of constraints for depended fields.
Thank you for your help.

How to use Assert\When in array data validation #49112

QuietNoise Jan 26, 2023

Replies: 1 suggested answer · 2 replies

MatTheCat Jan 26, 2023

MatTheCat Jan 26, 2023

QuietNoise Jan 26, 2023 Author

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QuietNoise
Jan 26, 2023

Replies: 1 suggested answer 2 replies

MatTheCat
Jan 26, 2023

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