Api-Platform：过滤规范化上下文组

Hello guys I just started using Api-Platform and I got stuck on this problem for several hours.

I have a Symfony4 Project and two Entities: Bill & Abo

Bill:

/**
 * @ORM\Entity(repositoryClass="App\Repository\BillRepository")
 * @ApiResource(attributes={
 *   "normalization_context"={"groups"={"bill-abo"}}
 * })
 */
class Bill {
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @var \DateTime
     *
     * @ORM\Column(name="date", type="date", nullable=false)
     * @Groups("bill-abo")
     */
    private $date;

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\Abo", inversedBy="bills")
     * @ORM\JoinColumn
     * @ApiSubresource
     * @Groups("bill-abo")
     */
    private $abo;
}

Abo:

/**
 * @ORM\Entity(repositoryClass="App\Repository\AboRepository")
 * @ApiResource
 */
class Abo
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="name", type="string", length=50, nullable=false)
     */
    private $name;

    /**
     * @var integer
     *
     * @ORM\Column(name="price", type="integer", nullable=false)
     * @Groups("bill-abo")
     */
    private $price;

    /**
     * @ORM\OneToMany(targetEntity="App\Entity\Bill", mappedBy="abo")
     */
    private $bills;
}

When I now call this url, /api/bills, I get back this data:

{
  "date": "2018-03-14T00:00:00+00:00",
  "abo": {
    "price": 960
  }
},
...

My goal now is to call an url, something like this: /api/bills?abo to get the result above and when I call /api/bills I only want the bill data (without the abo data), like this:

{
  "id": 14,
  "date": "2018-03-08T00:00:00+00:00",
  "abo": "/api/abos/1"
},
...

I read the docs and specifically the parts about the Group Filter and the Property Filter but I coulnd't figure out a solution.

Is this even possible and if yes how can I achieve this?

Thanks for your time and help!

You can leverage the Group Filter.

1. Add the GroupFilter on the Bill resource class like this @ApiFilter(GroupFilter::class, arguments={"overrideDefaultGroups": true, "whitelist": {"foo"}})
2. Add an new extra group called "foo" to the Bill::$abo property (don't add to any property in the Abo class)
3. Try /bills?groups[]=foo