Symfony 验证器服务和设置器中的 TypeErrors

Question

I'm currently confused by the way the Symfony validator service works. The way I currently understand it, it could completely fail and not report errors even before it can even validate an entity if a TypeError occurs while setting values.

The Symfony documentation uses Constraints in entities like this:

namespace App\Entity;

// ...
use Symfony\Component\Validator\Constraints as Assert;

class Author
{
    /**
     * @Assert\NotBlank
     */
    private $name;
}

Which are then used like this in the controllers:

public function author(ValidatorInterface $validator)
{
    $author = new Author();
    
    // ... do something to the $author object

    $author->setBirthDate('this will fail and not report'); // I added this line in myself, see rest of question.
  

    $errors = $validator->validate($author);

    if (count($errors) > 0) {
        /*
         * Uses a __toString method on the $errors variable which is a
         * ConstraintViolationList object. This gives us a nice string
         * for debugging.
         */
        $errorsString = (string) $errors;

        return new Response($errorsString);
    }

    return new Response('The author is valid! Yes!');
}

However, this will not nicely catch the exceptions that will be thrown when arguments of the wrong type are passed towards the setters of the entity variables. For example, the entity could have a field "birthDate" which is a DateTime, and which has a setter setBirthDate(DateTime $foo). When building the object before being able to call the validate() function, one could pass an argument of an incorrect type - say, the user submitted a string or nothing at all - which will obviously raise an exception.

Assuming that the validator service is supposed to be used like this, my question is as follows: how do I cleanly handle the data which could raise TypeErrors in the setters?

Do I not do any type hinting in my setters (accepting everything) and then validate it being a DateTime with the validator later on? Do I use a try/catch block while setting up the entity? Do I manually check the type of the user input before calling the setter? And if any of the last two, how would I cleanly report errors to the user? And even then, I think it would feel wrong to also be doing manual validation there when you're also doing it in the validator service.

I know about Forms and I assume this is not an issue when using those, but I still find the validator confusing either way.

Answer 1

You are missing the point of how the code should work, if you specify that the setter will accept DateTime object and DateTime object only PHP itself will ensure that the accepted argument is an instance of DateTime object. One way to go around that is to create a DTO(Data transfer object) eg. CreateAuthorRequest and create a symfony form type where you accept either string/DateTime(preferably string which will have a regex ensuring that the string is a valid datetime string). Then after you call $form->isValid() you can read the data from the DTO and be sure that it's valid. If you'll still struggle how this should be implemented correctly comment below the answer and I'll provide code samples

Also I wouldn't recommend to put that much annotations in your entity it will get messy pretty quick, prefer XML config over annotations.