Pass-down normalizer groups

[gijsgroenewegen]

This issue suggests to add support for a passdownGroup option in the normalizer bundle. With this option, the groups passed down to nested objects can be manually defined.

The following PHP class example will demonstrate the use case:

class Bar
{
    /**
     * @Bos\Normalize(group={"api_v3", "id_only"})
     * 
     * @var int
     */
    public $id;

    /**
     * @Bos\Normalize(group={"api_v3"}, passdownGroup="id_only")
     * 
     * @var Foo
     */
    public $foo;
}

class Foo
{
    /**
     * @Bos\Normalize(group={"api_v3", "id_only"})
     * 
     * @var int
     */
    public $id;

    /**
     * @Bos\Normalize(group={"api_v3"})
     * 
     * @var string
     */
    public $name;
}

Calling the normalizer like:

$this->normalizer->normalize($bar, 'api_v3');

Would result in:

{
  "id": 1,
  "foo": {
    "id": 1
  }
}

Instead of:

{
  "id": 1,
  "foo": {
    "id": 1,
    "name": "test"
  }
}

Without this feature, a lot of manual groups might have to be defined to support simple use cases like above.

[BowlOfSoup]

A few questions.

1. Your goal would be to only get the ID of certain type="collection", is that correct?
2. Could we instead of a passDownGroup use a specific option like normalizeIdOnly?
3. Or maybe we could add an indicator of the ID field like normalizeIdField=uuid (if the id field is not used, but another field is actually the identifier). We could even make it a class annotation (@Bos\Normalize(idField="uuid")) and use that in combination with normalizeIdOnly

The meaning of passDownGroup may be unclear.