Creating custom widget instance validation is weird due to controller type mismatch

[MellenIO]

Summary (*)

See this line of code:

https://github.com/magento/magento2/blob/2.4-develop/app/code/Magento/Widget/Controller/Adminhtml/Widget/Instance/Validate.php#L22

The function \Magento\Widget\Model\Widget\Instance::validate() is type hinted to return either a \Magento\Framework\Phrase or a bool
https://github.com/magento/magento2/blob/2.4-develop/app/code/Magento/Widget/Model/Widget/Instance.php#L294

This means the is_string check is going to fail. This further means that, unless you type cast the phrase to a string, you will not ever get a constructive error message out of the widget validation controller.
This isn't a huge issue for the most part with Magento core because of the frontend validation but for those creating custom widget validation rules it will break.

Examples (*)

$firstResult = __('Test message');
if ($firstResult !== true && is_string($firstResult)) {
    echo 'We have an error!';
}

Does not output anything.

Proposed solution

I think the easiest solution is just to change the validation controller line to the following:

if ($result !== true && (is_string($result) || ($result instanceof \Magento\Framework\Phrase)) {
// ...

On Magento sites with custom validation rules we've gotten around this by adding an afterValidate plugin to \Magento\Widget\Model\Widget\Instance which type casts the result to string (and returns a string for subsequent errors, rather than a phrase).

[m2-assistant]

Hi @MellenIO. Thank you for your report.
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[m2-assistant]

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[magento-engcom-team]

✅ Confirmed by @engcom-Echo
Thank you for verifying the issue. Based on the provided information internal tickets MC-33880 were created

Issue Available: @engcom-Echo, You will be automatically unassigned. Contributors/Maintainers can claim this issue to continue. To reclaim and continue work, reassign the ticket to yourself.

[magento-engcom-team]

Hi @MellenIO. Thank you for your report.
The issue has been fixed in #28379 by @zaximus84 in 2.4-develop branch
Related commit(s):

• f20b05b549bb0813ca21a0204588045fcb7e1c2a
• 1e4ef873f9639316617a33bdfb229a652d5d5ceb
• 3d82fe3a7bf0dc297d64a369cff03e246536e4a5
• 0f1c4599134fa43d2589ed0d0367d1f91b29ee31
• d0e8bda1a3b689b77b220c011249ec42c536b99d

The fix will be available with the upcoming 2.4.2 release.