[Python] Django rest framework nested serialization not working properly

I have these serializers in my app:

class ScheduleSerializer(serializers.ModelSerializer):
class Meta:
model = Schedule
fields = ('id',)

class DisciplineSerializer(serializers.ModelSerializer):
class Meta:
model = Discipline
fields = ('id',)


class WriteTeacherSerializer(serializers.ModelSerializer):
disciplines = DisciplineSerializer(many=True)
schedules = ScheduleSerializer(many=True)
class Meta:
model = Teacher
fields = ('phone_number', 'bio', 'price', 'disciplines', 'schedules')
depth = 1

def update(self, instance, validated_data):

print "\n"
#Debugging here
print validated_data
print "\n"
print instance.__dict__
print "\n"

instance.phone_number = validated_data['phone_number']
instance.bio = validated_data['bio']
instance.price = validated_data['price']
disciplines = validated_data.pop('disciplines')
schedules = validated_data.pop('schedules')
for discipline in disciplines:
try:
stored_discipline = Discipline.objects.get(id=discipline['id'])
instance.disciplines.add(stored_discipline)
except Discipline.DoesNotExist:
raise Http404

for schedule in schedules:
try:
stored_schedule = Schedule.objects.get(id=schedule['id'])
instance.schedules.add(stored_discipline)
except Discipline.DoesNotExist:
raise Http404
instance.save()
return instance


As you can see I am trying a nested serialization with the fields schedules and disciplines. I think I followed the documentation, but the nested serialization is not working when I test it. I printed the instance and validated_data objects and tested it on the shell.

I start the data in this format:

data = {u'phone_number': u'+99999999999', u'bio': u'BIO', u'price': 40, u'disciplines': [{'id': 1}], u'schedules': [{'id': 2}]}


I got a teacher instance and started the serializer like this:

serializer = WriteTeacherSerializer(teacher, data=data)


It shows True on a serializer.is_valid() call.

However when I try to save it the validated_data and the instance.__dict__ are like that:

#validated_data
{u'phone_number': u'+5584998727770', u'bio': u'BIO', u'price': 40, u'disciplines': [OrderedDict()], u'schedules': [OrderedDict()]}


#instance.__dict__
{'phone_number': u'', 'bio': u'', 'price': 50, 'profile_id': 2, '_state': <django.db.models.base.ModelState object at 0xb64a6bec>, 'id': 6}


They don't seem to notice the nested fields which makes the update() method not work.

Am I doing something wrong?

Here is my Teacher Model as well:

class Teacher(models.Model):

price = models.IntegerField(default=50)
phone_regex = RegexValidator(regex=r'^\+?1?\d{9,15}$', message="Wrong phone number format.")
phone_number = models.CharField(validators=[phone_regex], max_length=15, blank=True)
profile = models.OneToOneField(Profile, on_delete=models.CASCADE)
schedules = models.ManyToManyField(Schedule, related_name='schedules')
disciplines = models.ManyToManyField(Discipline, related_name='disciplines')
bio = models.CharField(max_length=200, blank=True)

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