Validation error with DRF PointField - "Enter a valid location" - django

Question

In one of my APIs, I am able to get the DRF extra field, PointField working.
In one of the other API where I am using PointField in a nested serializer, it is giving me a validation error.
{
"booking_address": {
"coordinates": [
"Enter a valid location."
]
}
}
And the payload data is
{
"booking_address": {
"coordinates" : {
"latitude": 49.87,
"longitude": 24.45
},
"address_text": "A123"
}
}
My serializers are below:
BookingSerializer
class BookingSerializer(FlexFieldsModelSerializer):
booked_services = BookedServiceSerializer(many=True)
booking_address = BookingAddressSerializer(required=False)
------
def validate_booking_address(self, address):
if address.get("id"):
address = BookingAddress.objects.get(id=address.get("id"))
else:
address["customer"] = self.context.get("request").user.id
serializer = BookingAddressSerializer(data=address)
if serializer.is_valid(): <---- error is coming from here
address = serializer.save()
else:
raise ValidationError(serializer.errors)
return address
My Address Serializer is defined as:
class BookingAddressSerializer(FlexFieldsModelSerializer):
coordinates = geo_fields.PointField(srid=4326)
customer = serializers.IntegerField(required=False)
And booking model is:
class BookingAddress(BaseTimeStampedModel):
customer = models.ForeignKey(settings.AUTH_USER_MODEL, related_name="booking_addresses", on_delete=models.CASCADE)
coordinates = models.PointField()
address_text = models.CharField(max_length=256)
Tried Debugging, been stuck here for a few hours now and not able to find the issue.
Any help will be appreciated.

Answer 1

Well, the problem is that to_internal_value() is called with a correct Pointfield, and because geofields.PointField only handles strings or dicts it fails.
Here's the code I used to reproduce the problem (trimmed down, with imports):
# models.py
from __future__ import annotations
import typing as t
from django.contrib.gis.db import models
from django.contrib.auth import get_user_model
User = get_user_model()
if t.TYPE_CHECKING:
from django.contrib.auth.models import User
class BaseTimeStampedModel(models.Model):
created_at = models.DateTimeField(auto_now_add=True)
last_modified = models.DateTimeField(auto_now=True)
class Meta:
abstract = True
class BookingAddress(BaseTimeStampedModel):
customer = models.ForeignKey(
User, related_name="booking_addresses", on_delete=models.CASCADE,
)
coordinates = models.PointField(geography=True, srid=4326)
address_text = models.CharField(max_length=256)
class Booking(BaseTimeStampedModel):
service = models.CharField(max_length=20)
address = models.ForeignKey(
BookingAddress, on_delete=models.CASCADE, related_name="booking"
)
# serializers.py
import json
from rest_framework import serializers
from rest_framework.exceptions import ValidationError
from drf_extra_fields import geo_fields
from .models import BookingAddress, Booking
from django.contrib.gis.geos import GEOSGeometry
from django.contrib.gis.geos.error import GEOSException
from django.contrib.gis.geos.point import Point
EMPTY_VALUES = (None, "", [], (), {})
class PointField(geo_fields.PointField):
default_error_messages = {
"invalid": "Enter a valid location.",
"json": "Invalid json",
"unknown": "Unknown cause",
"wrong_type": "Expected string or dict",
}
def to_internal_value(self, value):
if value in EMPTY_VALUES and not self.required:
return None
if isinstance(value, str):
try:
value = value.replace("'", '"')
value = json.loads(value)
except ValueError:
self.fail("json")
print(type(value))
if value and isinstance(value, dict):
try:
latitude = value.get("latitude")
longitude = value.get("longitude")
return GEOSGeometry(
"POINT(%(longitude)s %(latitude)s)"
% {"longitude": longitude, "latitude": latitude},
srid=self.srid,
)
except (GEOSException, ValueError) as e:
msg = e.args[0] if len(e.args) else "Unknown"
self.fail(f"unknown", msg=msg)
if isinstance(value, Point):
raise TypeError("Point received")
self.fail(f"wrong_type")
class BookingAddressSerializer(serializers.ModelSerializer):
coordinates = PointField(srid=4326)
class Meta:
model = BookingAddress
fields = ("coordinates", "customer_id")
class BookingSerializer(serializers.ModelSerializer):
booking_address = BookingAddressSerializer(required=False)
def validate_booking_address(self, address):
if address.get("id"):
address = BookingAddress.objects.get("id")
else:
address["customer"] = self.context.get("request").user.id
serializer = BookingAddressSerializer(data=address)
if serializer.is_valid():
address = serializer.save()
else:
raise ValidationError(serializer.errors)
return address
class Meta:
model = Booking
fields = ("service", "created_at", "last_modified", "booking_address")
read_only_fields = ("created_at", "last_modified")
# tests.py
import json
from django.contrib.auth import get_user_model
from django.test import TestCase
from .serializers import BookingSerializer
User = get_user_model()
class DummyRequest:
user = None
class BookingSerializerTest(TestCase):
payload = json.dumps(
{
"service": "Dry cleaning",
"booking_address": {
"coordinates": {"longitude": 24.45, "latitude": 49.87},
"address_text": "123 Main Street",
},
}
)
def test_serializer(self):
user = User.objects.create_user(username="test_user", password="pass123456")
request = DummyRequest()
request.user = user
serializer = BookingSerializer(
data=json.loads(self.payload), context={"request": request}
)
self.assertTrue(serializer.is_valid(raise_exception=True))
If you run the test you see in the output:
<class 'dict'>
<class 'django.contrib.gis.geos.point.Point'>
And the 2nd time is where it fails, because it cannot handle a Point. This is caused by you overstepping your boundaries in validate_booking_address(). This causes to_internal_value to be called twice, the 2nd time with the result of the previous.
You're trying to handle the entire convert > validate > save operation there and the method should only do the validate step. This means, check to see if the data matches the expected input.
A nested field should validate itself and be able to create itself. If you need request.user to create a valid model you should override create() as explained by the documentation:
If you're supporting writable nested representations you'll need to write .create() or .update() methods that handle saving multiple objects.