Normalization group not working in nested embedded entities

I have the following entity structure: BrandMessage has Campaign has (CampaignSettings and RunningTime). So when I call the /api/brand-messages api the entities CampaignSettings and RunningTime are nested in the third level. Also, CampaignSettings and RunningTime are embedded entities.

When I call the /api/campaigns api, everything works as expected. runningTime and settings are present:

{
  "@context": "/app_dev.php/api/contexts/Campaign",
  "@id": "/app_dev.php/api/campaigns",
  "@type": "hydra:Collection",
  "hydra:member": [
    {
      "@id": "/app_dev.php/api/campaigns/e64a026e-1b88-11e7-8825-0242ac110002",
      "@type": "Campaign",
      "app": "/app_dev.php/api/apps/e64d3274-11e7-1b88-8825-0242ac110002",
      "runningTime": {
        "daysLeftTillEnd": 99,
        "daysLeftTillStart": -74,
        "end": "2017-07-16T02:31:13+00:00",
        "isFinished": false,
        "start": "2017-01-23T08:02:29+00:00"
      },
      "settings": {
        "participationLimit": 1,
        "receiptMandatory": true,
        "requiredProductCount": 5,
        "rewardInEuroCent": 100
      },
      "title": "...",
      "description": "..."
    },
   ...
}

But when I call the /api/brand-messages api, these properties (runningTime and settings) are just null:

{
  "@context": "/app_dev.php/api/contexts/BrandMessage",
  "@id": "/app_dev.php/api/brand-messages",
  "@type": "hydra:Collection",
  "hydra:member": [
    {
      "@id": "/app_dev.php/api/brand-messages/e64d3274-1b88-11e7-8825-0242ac110002",
      "@type": "BrandMessage",
      "backgroundImage": null,
      "campaign": {
        "@id": "/app_dev.php/api/campaigns/e64a3837-1b88-11e7-8825-0242ac110002",
        "@type": "Campaign",
        "app": "/app_dev.php/api/apps/e64d3274-11e7-1b88-8825-0242ac110002",
        "runningTime": null,
        "settings": null,
        "title": "...",
        "description": "..."
      },
      "colorPair": "secondary",
      "httpCallToActionLabel": "",
      "httpLink": "",
      "important": true,
      "type": "CAMPAIGN",
      "title": "..."
    },
    ...
  ],
  ...
}

I double checked all the serialisation groups and they even work in the third nesting level for title and description. Is there a default nesting limit for nested properties or something like that? Or am I facing a bug? 😃

[nik-lampe]

@soyuka yes, while applying this framework (which I really love btw) in my project I stumbled across multiple problems and was not aware, that they might all have the same or similar root cause. It was totally confusing for me as well. Sorry, about that 😃

[soyuka]

@nik-lampe you wrote lots of different issues / comments so it’s hard to track ^^. I added a comment in your pull request, but if there are 2 different problems we need to carefully test both and fix both separately!

1. This null issue (IMHO it’s a serialization group issue, not related to how the ResourceClassResolver works (or maybe but I’ve a lot of embedded relations and no such issue)
2. Then there is https://github.com/api-platform/core/issues/1025. This is indeed a bug where the Parent entity is not aware of the Child metadata. Therefore, it can not serialize properties it doesn’t know of. This is harder to fix, because the metadata is the one from Parent::class though it should be Parent::class + Child::class. The good question there is “how do we find every child that extends the parent?”. An easy fix is might be to patch this class by retrieving the metadata for table inheritance.