DRF error messages combine model and custom field error messages in response - django-rest-framework

Question

I have this model in django:
product_name = models.CharField(max_length=20, blank=False, required = True)
code = models.CharField(max_length = 13, blank = False, required= True)
product_note = models.CharField(max_length = 2000, blank = True, required=False)
There is a custom validator and sanitizor for code which is applied in serializer. Now my issue is if both fields are incorrect (missing product_name and incorrect code), I get reply :"this field is required" for the product name and the code error message is never shown. If product_name is passed according to its model definitions though, the code error message is shown.
Is there a way both the model definition (i.e. required) and custom validation can be processed and returned at once?
from products.models import Product
from rest_framework import serializers
from validations.product_validators import valid_product_code
class NewProductSerializer(serializers.ModelSerializer):
def validate(self, data):
# validate data here
err_msg = {}
code = valid_product_code(data['code'])
if code == '':
err_msg['code']=['The entered product do not follow product code rules and could not be sanitized']
if err_msg:
raise serializers.ValidationError(err_msg)
data['code'] = code
return data
class Meta:
model = Product
fields = ('product_name', 'code','product_note')

Answer 1

if code fields is not empty serializer call validate_code() method.
class NewProductSerializer(serializers.ModelSerializer):
class Meta:
model = Product
fields = ('product_name', 'code','product_note')
def validate_code(self, value):
# validate data here
err_msg = {}
code = valid_product_code(value)
if code == '':
err_msg['code']=['The entered product do not follow product code rules and could not be sanitized']
if err_msg:
raise serializers.ValidationError(err_msg)
return value