Creating a custom Type Guesser ¶

// src/Form/TypeGuesser/PHPDocTypeGuesser.php
namespace App\Form\TypeGuesser;

use Symfony\Component\Form\Extension\Core\Type\CheckboxType;
use Symfony\Component\Form\Extension\Core\Type\IntegerType;
use Symfony\Component\Form\Extension\Core\Type\NumberType;
use Symfony\Component\Form\Extension\Core\Type\TextType;
use Symfony\Component\Form\Guess\Guess;
use Symfony\Component\Form\Guess\TypeGuess;

class PHPDocTypeGuesser implements FormTypeGuesserInterface
{
    public function guessType(string $class, string $property): ?TypeGuess
    {
        $annotations = $this->readPhpDocAnnotations($class, $property);

        if (!isset($annotations['var'])) {
            return null; // guess nothing if the @var annotation is not available
        }

        // otherwise, base the type on the @var annotation
        return match($annotations['var']) {
            // there is a high confidence that the type is text when
            // @var string is used
            'string' => new TypeGuess(TextType::class, [], Guess::HIGH_CONFIDENCE),

            // integers can also be the id of an entity or a checkbox (0 or 1)
            'int', 'integer' => new TypeGuess(IntegerType::class, [], Guess::MEDIUM_CONFIDENCE),

            'float', 'double', 'real' => new TypeGuess(NumberType::class, [], Guess::MEDIUM_CONFIDENCE),

            'boolean', 'bool' => new TypeGuess(CheckboxType::class, [], Guess::HIGH_CONFIDENCE),

            // there is a very low confidence that this one is correct
            default => new TypeGuess(TextType::class, [], Guess::LOW_CONFIDENCE)
        };
    }

    protected function readPhpDocAnnotations(string $class, string $property): array
    {
        $reflectionProperty = new \ReflectionProperty($class, $property);
        $phpdoc = $reflectionProperty->getDocComment();

        // parse the $phpdoc into an array like:
        // ['var' => 'string', 'since' => '1.0']
        $phpdocTags = ...;

        return $phpdocTags;
    }

    // ...
}