serializer.data is missing some of the data - django

Question

Context: I am having problem accessing fields which are validated by nested serializers.
I have a very sample model as shown below.
For 2 of the fields I have their specific serializers. When I try to access the data it returns all the fields except the one validated by the specific serializers.
Models looks like this
class Sampler(models.Model):
sample_name = models.CharField(unique=True, max_length=100)
sampling_by = JSONField(max_length=100)
extractions = JSONField(max_length=100)
max_samples = models.IntegerField(default=100)
Serializers
class ExtractionsSerializer(serializers.BaseSerializer):
table_name = serializers.CharField()
extraction_type = serializers.ChoiceField(["ABC"])
dependencies = serializers.ListField(child=RecursiveField(), allow_empty=True, required=False)
class SamplingBySerializer(serializers.BaseSerializer):
"""
Validate sampling_by
"""
def to_internal_value(self, samples):
methods = ["ABC"]
sampling_not_supported = [sample for sample in samples
if sample['by'] not in methods]
if sampling_not_supported:
raise ValidationError("{} not in {}".format(sampling_not_supported, methods))
class SamplerSerializer(serializers.ModelSerializer):
extractions = ExtractionsSerializer(read_only=True)
sampling_by = SamplingBySerializer(read_only=True)
class Meta:
model = Sampler
fields = ('sample_name', 'database', 'schema', 'sampling_by', 'extractions', 'max_samples')
Now I do
data = {
"database": "postgresql://..",
"sampling_by":[{
"by":"ABC",
"value": ["l32=turn_the"]
}],
"max_samples":3,
"extractions" : [{
"table_name": "person",
"extraction_type": "ABC"
}]
}
sampler = SamplerSerializer(data=data)
sampler.is_valid() #returns True
sampler.data => does not contain data of the nested fields. Like the `sampling_by` and `extractions`. Contains all other fields
sampler.validated_data => same problem as above
Any help would be appreciated! thanks

Answer 1

You probably missed the fact that your nested serializers are flagged as read_only=True
class SamplerSerializer(serializers.ModelSerializer):
extractions = ExtractionsSerializer(read_only=True)
sampling_by = SamplingBySerializer(read_only=True)
Remove that part, implement the serializer's create / update and you're good to go.
On a side note, it doesn't make sense to access serializer.data when deserializing.
Edit: the authority source is validated_data.