Django Restful: Nested Serializers - django

Question

I'm adding a 'tests' field to my 'Sample' model, where 'tests' will be a list of 'TestRequest' objects. Currently, I'm getting this error:
Got AttributeError when attempting to get a value for field `tests` on serializer `SampleSerializer`.
The serializer field might be named incorrectly and not match any attribute or key on the `Sample` instance.
Original exception text was: 'Sample' object has no attribute 'tests'.
'tests' is not a field on my model. I'm just trying to add it to the serialized data. Currently, I can get a nested serializer to work for 'klass' but that is because it's defined in the model.
Models:
class Sample(models.Model):
name = models.CharField(max_length=50, null=False, blank=False)
comments = models.TextField(null=True, blank=True)
klass = models.ForeignKey('samples.Batch', null=True, blank=True,
related_name='samples', verbose_name='Batch')
product = models.ForeignKey('customers.Product', blank=False)
NOTRECEIVED = 'nr'
RECEIVED = 'rc'
DISCARDED = 'dc'
DEPLETED = 'dp'
SAMPLE_STATUS = (
(NOTRECEIVED, 'not received'),
(RECEIVED, 'received'),
(DISCARDED, 'discarded'),
(DEPLETED, 'depleted'),
)
status = models.CharField(
max_length=2, choices=SAMPLE_STATUS, default=NOTRECEIVED)
is_recycling = models.BooleanField(default=False)
is_submitted = models.BooleanField(default=False)
received_date = models.DateTimeField(
_('date received'), null=True, blank=True)
class TestRequest(models.Model):
client = models.ForeignKey('customers.Client')
company = models.ForeignKey('customers.Company')
sample = models.ForeignKey('samples.Sample')
procedure_version = models.ForeignKey('registery.ProcedureVersion')
replicates = models.PositiveIntegerField(editable=True, null=True, blank=True)
created_date = models.DateTimeField('Date created', auto_now_add=True)
last_updated = models.DateTimeField(auto_now=True)
comments = models.TextField('Comments', blank=True)
Serializers:
class TestSerializer(serializers.ModelSerializer):
href = serializers.HyperlinkedIdentityField(lookup_field='pk', lookup_url_kwarg='pk', read_only=True, view_name='samples_api:test-detail')
class Meta:
model = TestRequest
fields = ('id', 'href',)
class SampleBatchSerializer(serializers.ModelSerializer):
href = serializers.HyperlinkedIdentityField(
lookup_field='pk', lookup_url_kwarg='batch_pk', read_only=True, view_name='samples_api:batch-detail')
class Meta:
model = Batch
fields = ('id', 'href',)
class SampleSerializer(serializers.ModelSerializer):
tests = TestSerializer(many=True)
klass = SampleBatchSerializer(many=False)
class Meta:
model = Sample
# list_serializer_class = FilteredListSerializer
fields = ('id', 'name', 'tests', 'klass',)
def create(self, validated_data):
...
def update(self, instance, validated_data):
...
Viewsets:
class TestRequestViewSet(viewsets.ModelViewSet):
"""
Viewset for the TestRequest model
"""
serializer_class = TestRequestSerializer
def get_queryset(self):
client = get_object_or_404(Client, user=self.request.user)
return TestRequest.objects.filter(company=client.company)
def perform_create(self, serializer):
# Override default creatation to provide request based information.
client = get_object_or_404(Client, user=self.request.user)
company = client.company
serializer.save(client=client, company=company)
class SampleViewSet(viewsets.ModelViewSet):
"""
Viewset for the Sample model
"""
serializer_class = SampleSerializer
def get_queryset(self):
client = get_object_or_404(Client, user=self.request.user)
return Sample.objects.filter(klass__company=client.company)
I would rather not have to add the field to the model. A 'Sample' can have many 'TestRequest's but a 'TestRequest' can only have one 'Sample'.
How do I get my serializer to add the 'tests' field that isn't in the model?

Answer 1

in your SampleSerializer. You have specified 'tests' which is not in your Sample class in your model...
Use nested SerializerMethodField as below....
tests = serializers.SerializerMethodField()
def get_tests(self, obj):
var=TestRequestSerializer(obj.id)
return var.data