added validations

care/facility/api/serializers/hospital_doctor.py

@@ -1,5 +1,5 @@
 from rest_framework import serializers
-
+from rest_framework.exceptions import ValidationError
 from care.facility.api.serializers import TIMESTAMP_FIELDS
 from care.facility.models import DOCTOR_TYPES, HospitalDoctors
 from config.serializers import ChoiceField
@@ -16,3 +16,9 @@ class Meta:
             "area_text",
         )
         exclude = TIMESTAMP_FIELDS + ("facility", "external_id")
+
+    def validate(self, attrs):
+        # validate that the doctor count is positive
+        if attrs["count"] < 0:
+            raise ValidationError("Doctor count cannot be negative")
+        return super().validate(attrs)