How to access a field inside a nested Serializer and make post request work?

I am working on a POST request where first a Tag is saved and then a Tagging - these are text labels relating to a picture (Resource).

These are the two serializers:

class TagSerializer(serializers.ModelSerializer):

  class Meta:
    model = Tag
    fields = ('name', 'language')

  def create(self, data):
    tag_data = validated_data.pop('tag')
    Tag.objects.create(**tag_data)
    return tag_data

  def to_representation(self, data):
    data = super().to_representation(data)
    return data

class TaggingSerializer(serializers.ModelSerializer):
  tag_id = serializers.PrimaryKeyRelatedField(queryset=Tag.objects.all(),
                                              required=False,
                                              source='tag',
                                              write_only=False)
  # tag = TagSerializer(required=False, write_only=False).data.get('name')
  resource_id = serializers.PrimaryKeyRelatedField(queryset=Resource.objects.all(),
                                                   required=True,
                                                   source='resource',
                                                   write_only=False)
  gameround_id = serializers.PrimaryKeyRelatedField(queryset=Gameround.objects.all(),
                                                    required=False,
                                                    source='gameround',
                                                    write_only=False)
  user_id = serializers.PrimaryKeyRelatedField(queryset=CustomUser.objects.all(),
                                               required=False,
                                               source='user',
                                               write_only=False)

  class Meta:
    model = Tagging
    fields = ('id', 'user_id', 'gameround_id', 'resource_id', 'tag_id', 'created', 'score', 'origin')
    depth = 1

  def create(self, validated_data):
    """Create and return a new tagging"""

    tagging = Tagging(
      user=validated_data.get("user"),
      gameround=validated_data.get("gameround"),
      resource=validated_data.get("resource"),
      tag=validated_data.get("tag"),
      created=datetime.now(),
      score=validated_data.get("score"),
      origin=validated_data.get("origin")
    )
    tagging.save()
    return tagging

  def to_representation(self, data):
    data = super().to_representation(data)
    return data

This is the post request in the view:

    def post(self, request, *args, **kwargs):
        if not isinstance(request.user, CustomUser):
            current_user_id = 1
        else:
            current_user_id = request.user.pk
        gameround = request.data.get('gameround', '')
        random_resource = request.data.get('resource', '')
        created = datetime.now()
        score = 0
        origin = ''
        name = request.data.get('name', '')
        language = request.data.get('language', '')

        tag_serializer = TagSerializer(data=request.data)
        tagging_serializer = TaggingSerializer(data=request.data)

        if Tag.objects.all().filter(name=name, language=language).exists():
            if Tagging.objects.all().filter(user=current_user_id, gameround=gameround, resource=random_resource,
                                            tag=Tag.objects.all().get(name=name, language=language),
                                            created=created, score=score+5, origin=origin).exists():

                if tag_serializer.is_valid(raise_exception=True):
                    tag = request.data
                    tag_serializer.save(tag)
                    if tagging_serializer.is_valid(raise_exception=True):
                        tagging_serializer.save(tagging=request.data, tag=tag)
                        return Response({"status": "success", "data": tagging_serializer.data},
                                        status=status.HTTP_201_CREATED)
                    else:
                        return Response({"status": "success", "data": tag_serializer.data},
                                        status=status.HTTP_201_CREATED)
                else:
                    return Response({"status": "error", "data": tag_serializer.errors},
                                    status=status.HTTP_400_BAD_REQUEST)

I have tested the serializers by getting objects in the browser. This is what a Tag object looks like in the browser:

{ "name": "yellow", "language": "en" }

this is the Tagging object:

{ "id": 27718, "user_id": 26213, "gameround_id": 27, "resource_id": 7, "tag": { "id": 461345, "name": "sphere", "language": "en" }, "created": "2020-10-28T23:43:40.544000Z", "score": 0, "origin": "" }

The POST request for a Tagging object only works if I give it an id of a Tag, I cannot work with a nested Tag as I am trying to in the Post method. What I tried out is the line that I have commented out in the TaggingSerializer.

What I also don't understand is:

• Why does the Tag object have an id when it is nested inside the Tagging object, even though I have removed the field 'id' from the TagSerializer?

• How can I make my post request work?

Please help, I have tried everything out that I could think of and find online so far.