Symfony Validation

validation.php

<?php

$constraints = [
    // Here is the issue, I want to assert the vendor_num key
    // of the $vendor array below is both not blank AND has
    // a length <= 24 (and who knows, more constraints down the road).
    // The issue is that Collection() expects vendor_num to
    // be an array. How to do I chain these without calling
    // addPropertyConstraint() a bunch because I don't have access to it.
    'vendor_num' => new Assert\Collection([
        'constraints' => [
        new Assert\NotBlank,
        new Assert\Length([
            'max' => 24
        ])]
    ]),
    'display_name' => new Assert\Length(['max' => 2]),
    'email_address' => new Assert\Email
];

$vendor = [
    'vendor_num' => 'THIS IS A VERY LONG VENDOR NUMBER THAT SHOULD FAIL',
    'display_name' => 'This should fail',
    'email_address' => 'invalid'
];

$constraint = new Assert\Collection($constraints);

$violations = $this->validator
    ->validateValue($vendor, $constraint);

You're so close!

$constraints = [
    'vendor_num' => array(
        new Assert\NotBlank,
        new Assert\Length([
            'max' => 24
        ])
    ),
    // ...
];