Can I make a serializer fail silently? - django

Question

I have to serializer a list of email addresses. If one of them contains a wrong character (in one case, it was a ":" at the end of the address) my serializer throws an error, rejects serializing the whole set of addresses and returns a HTTP 400. Is there a way to "pop" the faulty email address from the list but still serialize the remaining correct addresses?
View:
#action(detail=False, methods=['post'])
def match(self, request):
serializer = FriendFinderSerializer(data=request.data, many=True)
if serializer.is_valid():
contacts = serializer.validated_data
matched, unmatched = self.match_contacts(contacts)
serialized_matched = FriendFinderSerializer(matched, many=True)
serialized_unmatched = FriendFinderSerializer(unmatched, many=True)
data = {
'matched': serialized_matched.data,
'unmatched': serialized_unmatched.data,
}
return Response(data, status=status.HTTP_200_OK)
else:
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
Serializer:
class FriendFinderSerializer(serializers.Serializer):
id = serializers.IntegerField(required=False)
image = serializers.ImageField(required=False)
record_id = serializers.CharField()
phone_numbers = serializers.ListField(child=serializers.CharField(), required=False)
email_addresses = serializers.ListField(child=serializers.EmailField(), required=False)
relationship_id = serializers.CharField(required=False)
relationship_status = serializers.CharField(required=False)

Answer 1

A place to start would be to iterate over request.data and handle each element within a loop. This is definitely a break from the norm and you'll need to determine how to handle cases where there is good and bad data.
#action(detail=False, methods=['post'])
def match(self, request):
successful_data = []
error_data = []
for element in request.data:
serializer = FriendFinderSerializer(data=element, many=False)
if serializer.is_valid():
contacts = serializer.validated_data
matched, unmatched = self.match_contacts(contacts)
serialized_matched = FriendFinderSerializer(matched, many=True)
serialized_unmatched = FriendFinderSerializer(unmatched, many=True)
successful_data.append({
'matched': serialized_matched.data,
'unmatched': serialized_unmatched.data,
})
else:
error_data.append(serializer.errors)
# Determine what status to return and how to handle successes and errors.
Personally, I'd either make smaller requests rather than posting all the data or handle the case in which an error in one FriendFinderSerializer causes all to fail. What you're attempting to do is likely to cause you more pain than the other options.

Answer 2

This is kind of a hack, but it works.
You need to define a custom field and there you need to override to_internal_value method of the field. Like this:
class CustomField(serializers.Field):
def __init__(self, custom_validation, *args, **kwargs):
self.custom_validation=custom_validation # <-- Here pass your custom validation regex
super(CustomField, self).__init__(*args, **kwargs)
def to_representation(self, obj):
return obj
def to_internal_value(self, obj):
try:
match = re.search(self.custom_validation, obj) # <-- validate the value against regex
if match:
return obj
except Exception as e:
pass
return None # <-- If exception occurs, return None
Or override the EmailField like this:
class CustomEmailField(serializer.EmailField):
def run_validation(self,*args, **kwargs):
try:
return super(CustomEmailField, self).run_validation(*args,**kwargs) # <-- Runs validation, but it fails, returns None
except:
return None
And use it in the Serializer like this:
email = CustomField(r"(^[a-zA-Z0-9_.+-]+#[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$)") # regex for email
Or
email = CustomEmailField()
And if you want to pop the invalid values from ListField, then you can override to_representation like this:
class CustomListField(serializers.ListField):
def to_representation(self, data):
childs = super(CustomListField, self).to_representation(data)
new_childs = []
for child in childs:
if child:
new_childs.append(child)
return new_childs
Then, use it in the Serializer:
email_addresses = CustomListField(child=CustomEmailField(), required=False)