How to get union types of a class property when using ReflectionProperty?

Question

I am trying to get the union types of a property on a class using ReflectionProperty. But having no luck.

class Document 
{
   // Standard type
   public string $companyTitleStandard;

   // Union types
   public DocumentFieldCompanyTitle|string $companyTitleUnion;
}

Standard type works fine. Union types however, I cannot for love nor money figure out how to implement.

$rp = new ReflectionProperty(Document::class, 'companyTitleStandard');
echo $rp->getType()->getName(); // string

$rp = new ReflectionProperty(Document::class, 'companyTitleUnion');
echo $rp->getTypes(); // Exception: undefined method ReflectionProperty::getTypes()    
echo $rp->getType()->getTypes(); // Exception: undefined method ReflectionNamedType::getTypes()

I'm ultimately looking for something like this to play with:

['DocumentFieldCompanyTitle', 'string']

Any ideas anyone? Thanks in advance

Answer 1

On union types, the first

$rp->getType()

will return a ReflectionUnionType.
To get the names of the individual types in the union, you then need to iterate through

$rp->getType()->getTypes()

So to just output the types:

foreach ($rp->getType()->getTypes() as $type) {
    echo $type->getName() . PHP_EOL;
}

If you rather get the types for union in a normal array, you can do this:

$unionTypes = array_map(function($type) { 
    return $type->getName();
}, $rp->getType()->getTypes());

Or for short in a one-liner:

$unionTypes = array_map(fn($type) => $type->getName(), $rp->getType()->getTypes());

Here's a demo: https://3v4l.org/SlbXX#v8.0.19