When a ModelSerializer is nested, it loses its custom defined fields

[droidzone]

I am using DRF's ModelSerializer and Nested relationships.

Problem:

The ModelSerializer, ProcedureSerializer when displayed shows all the custom fields defined on it correctly. However, when ProcedureSerializer is nested into customerSerializer, the fields of ProcedureSerializer shown are only those original fields defined in its model, and it loses the custom defined fields.

The issue is that in nested modelserializer, some of the fields defined on, and visible on listing the nested serializer do not show up when listing the parent.

Models:

    class customer(models.Model):
        cstid = models.AutoField(primary_key=True, unique=True)
        name = models.CharField(max_length=35, blank=False)
        ...SNIPPED

        class Meta:
            unique_together = ["name", "mobile", "linkedclinic"]
            ordering = ['name']

        def __str__(self):
            return self.name    
        
    class Procedure(models.Model):
        procid = models.AutoField(primary_key=True, unique=True)
        timestr = models.DateTimeField(default=timezone.now)
        template = models.ForeignKey(
            ProcedureTemplate, on_delete=models.CASCADE, blank=True, null=True)
        clinic = models.ForeignKey(Clinic, on_delete=models.CASCADE)
        doctor = models.ForeignKey(
            doctor, on_delete=models.SET_NULL, blank=True, null=True)
        customer = models.ForeignKey(
            customer, on_delete=models.CASCADE, null=False, related_name='procedures')

        def __str__(self):
            return f'{self.template} for {self.customer} on {self.timestr}'

        def eventtime(self):
            class_date = timezone.localtime(self.timestr)
            return class_date.strftime("%d-%m-%Y %I:%M %p")    

Serializers:

class FindingSerializer(serializers.ModelSerializer):
    class Meta:
        model = Finding
        depth = 1
        fields = [
            'fid',
            'fieldheading',
            'value',
            'linkedprocedure',
        ]
        
class ProcedureSerializer(serializers.ModelSerializer):
    finding_proc = FindingSerializer(many=True, read_only=True)
    
    class Meta:
        model = Procedure
        depth = 2
        fields = [
            'procid',
            'timestr',
            'template',
            'clinic',
            'doctor',
            'customer',
            'eventtime',
            'finding_proc',
        ]
        
class customerSerializer(ConvertNoneToStringSerializerMixin, serializers.ModelSerializer):
    def get_unique_together_validators(self):
        """Overriding method to disable unique together checks"""
        return []

    class Meta:
        model = customer
        depth = 3
        biovar_data = Biovariable_dataSerializer(
            read_only=True, many=True)  # many=True is required
        procedures = ProcedureSerializer(
            read_only=True, many=True)  # many=True is required
        # allergies = allergiesSerializer(
        #     read_only=True, many=True)  # many=True is required
        fields = [
            'cstid',
            'date_of_registration',
            'insurance_number',
            'name',
            'age',
            'ageyrs',
            'agemnths',
            'dob',
            'gender',
            'maritalstatus',
            'mobile',
            'alternate',
            'email',
            'address',
            'city',
            'occupation',
            'bloodgroup',
            'linkedclinic',
            'allergies_data',
            'biovar_data',
            'procedures'
        ]
        validators = []
        none_to_str_fields = ('insurance_number', )

If I display a procedure instance: GET /api/procedures/209/, All the required fields show up:

HTTP 200 OK
Allow: GET, PUT, PATCH, DELETE, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "procid": 209,
    "timestr": "2022-02-02T17:23:55.048232+05:30",
    "template": 1,
    "clinic": 21,
    "doctor": 4,
    "customer": 5596,
    "eventtime": "02-02-2022 05:23 PM",
    "finding_proc": [
        {
            "fid": 1423,
            "fieldheading": {
                "procid": 5,
                "name": "Nasal mucosa",
                "default": "Nasal mucosa appears normal.",
                "sortorder": 1,
                "fieldtype": "heading1",
                "template": 1
            },
            "value": "",
            "linkedprocedure": {
                "procid": 209,
                "timestr": "2022-02-02T17:23:55.048232+05:30",
                "template": 1,
                "clinic": 21,
                "doctor": 4,
                "customer": 5596
            }
        },
        {
            "fid": 1424,
            "fieldheading": {
                "procid": 6,
                "name": "Turbinates",
                "default": "Bilateral inferior, middle and superior turbinates appear normal.",
                "sortorder": 15,
                "fieldtype": "heading1",
                "template": 1
            },
            "value": "Left MT bulky, suggestive of concha bullosa",
            "linkedprocedure": {
                "procid": 209,
                "timestr": "2022-02-02T17:23:55.048232+05:30",
                "template": 1,
                "clinic": 21,
                "doctor": 4,
                "customer": 5596
            }
        },
        {
            "fid": 1425,
            "fieldheading": {
                "procid": 7,
                "name": "Septum",
                "default": "No significant nasal septal deviation.",
                "sortorder": 5,
                "fieldtype": "heading1",
                "template": 1
            },
            "value": "",
            "linkedprocedure": {
                "procid": 209,
                "timestr": "2022-02-02T17:23:55.048232+05:30",
                "template": 1,
                "clinic": 21,
                "doctor": 4,
                "customer": 5596
            }
        },
        {
            "fid": 1426,
            "fieldheading": {
                "procid": 8,
                "name": "Middle meatus",
                "default": "Bilateral middle meatus normal. No discharge, or polyps.",
                "sortorder": 50,
                "fieldtype": "heading1",
                "template": 1
            },
            "value": "",
            "linkedprocedure": {
                "procid": 209,
                "timestr": "2022-02-02T17:23:55.048232+05:30",
                "template": 1,
                "clinic": 21,
                "doctor": 4,
                "customer": 5596
            }
        },
        {
            "fid": 1427,
            "fieldheading": {
                "procid": 9,
                "name": "Inferior Meatus",
                "default": "Inferior Meatus is normal. Opening of Hasner's valve normal.",
                "sortorder": 30,
                "fieldtype": "heading1",
                "template": 1
            },
            "value": "Nasopharynx shows adenoid enlargement, occupying less than 2/3rd of the posterior choana.",
            "linkedprocedure": {
                "procid": 209,
                "timestr": "2022-02-02T17:23:55.048232+05:30",
                "template": 1,
                "clinic": 21,
                "doctor": 4,
                "customer": 5596
            }
        },
        {
            "fid": 1428,
            "fieldheading": {
                "procid": 10,
                "name": "Sphenoethmoidal recess",
                "default": "Bilateral sphenoethmoidal recesses normal",
                "sortorder": 60,
                "fieldtype": "heading1",
                "template": 1
            },
            "value": "",
            "linkedprocedure": {
                "procid": 209,
                "timestr": "2022-02-02T17:23:55.048232+05:30",
                "template": 1,
                "clinic": 21,
                "doctor": 4,
                "customer": 5596
            }
        },
        {
            "fid": 1429,
            "fieldheading": {
                "procid": 11,
                "name": "Final Impression",
                "default": "Nasal endoscopy normal",
                "sortorder": 1000,
                "fieldtype": "heading1",
                "template": 1
            },
            "value": "Adenoid hypertrophy noted",
            "linkedprocedure": {
                "procid": 209,
                "timestr": "2022-02-02T17:23:55.048232+05:30",
                "template": 1,
                "clinic": 21,
                "doctor": 4,
                "customer": 5596
            }
        }
    ]
}    

But, if I try to view the serializer customerSerializer which nests ProcedureSerializer, all the fields of ProcedureSerializer do not show up:

`GET /api/customer/5596/`

{
    "cstid": 5596,
    "name": "Some name",
    "age": "10yr",
    "ageyrs": 9,
    SNIPPED
    "linkedclinic": {},
    "procedures": [
        {
            "procid": 209,
            "timestr": "2022-02-02T17:23:55.048232+05:30",
            "template": {
                "templid": 1,
                "title": "DNE",
                "description": "Diagnostic Nasal Endoscopy",
                "clinic": {
                    "clinicid": 10,
                    "SNIP
                }
            },
            "clinic": {
                "clinicid": 21,
                SNIP
            },
            "doctor": {
                "docid": 4,
                SNIP
            },
            "customer": {
                "cstid": 5596,
                "date_of_registration": "2021-12-25",
                SNIP
                }
            }
        }
    ]
}

Thus, it is noted that two of those fields which are there in ProcedureSerializer, including eventtime (which is actually a model method) and finding_proc (which is a nested serializer) are missing from ProcedureSerializer.

repr(ProcedureSerializer()) gives:

"ProcedureSerializer():\n    procid = IntegerField(read_only=True)\n    timestr = DateTimeField(required=False)\n    template = PrimaryKeyRelatedField(allow_null=True, queryset=ProcedureTemplate.objects.all(), required=False)\n    clinic = PrimaryKeyRelatedField(queryset=Clinic.objects.all())\n    doctor = PrimaryKeyRelatedField(allow_null=True, queryset=doctor.objects.all(), required=False)\n    customer = PrimaryKeyRelatedField(queryset=customer.objects.all())\n    eventtime = ReadOnlyField()\n    finding_proc = FindingSerializer(many=True, read_only=True):\n        fid = IntegerField(read_only=True)\n        fieldheading = NestedSerializer(read_only=True):\n            procid = IntegerField(read_only=True)\n            name = CharField(max_length=200)\n            default = CharField(max_length=1000)\n            sortorder = IntegerField(max_value=2147483647, min_value=-2147483648, required=False)\n            fieldtype = ChoiceField(choices=(('heading1', 'Heading1'), ('heading2', 'Heading2')), required=False)\n            template = PrimaryKeyRelatedField(queryset=ProcedureTemplate.objects.all())\n        value = CharField(allow_blank=True, max_length=5000, required=False)\n        linkedprocedure = NestedSerializer(read_only=True):\n            procid = IntegerField(read_only=True)\n            timestr = DateTimeField(required=False)\n            template = PrimaryKeyRelatedField(allow_null=True, queryset=ProcedureTemplate.objects.all(), required=False)\n            clinic = PrimaryKeyRelatedField(queryset=Clinic.objects.all())\n            doctor = PrimaryKeyRelatedField(allow_null=True, queryset=doctor.objects.all(), required=False)\n            customer = PrimaryKeyRelatedField(queryset=customer.objects.all())"

What is happening here? Why are the fields being lost from the nested ModelSerializer?

[Smixi]

Hi,

I think it it because you setup the procedure field in the Meta class instead of the main class. Moving it outside works :

[droidzone]

Thank you. I was at my wit's end trying to figure out this!