Hey there,
I am trying to implement some generic nested saving and I've come a long
way so far. But I'm struggling with this part. I want to reuse the
instances for saving of reverse foreign keys and many to many's etc. but I
can't seem to find the list in the ListSerializer. I followed the docs
<http://www.django-rest-framework.org/api-guide/serializers/#customizing-multiple-update>
and created a custom ListSerializer which inherits from the normal list
serializer, but there is no instance and it's not instantiated with data so
I can't access the data, validated_data or is_valid.
My code simplified looks something like this. It's as bare as possible but
I hope it get's the point across.
class BookListSerializer(serializers.ListSerializer):
def save(self, **kwargs):
# The super breaks because of incomplete instantiating.
# Also kwargs is empty.
# There is only one child here and not a list to be found.
# In (pseudo) code it would look something like this, but there is
no instance:
for book in self.validated_data:
if book.instance:
self.child.update(book)
else:
self.child.create(book)
return my_list
class BookSerializer(serializers.ModelSerializer):
# Some fields.
class Meta:
model = Book
list_serializer_class = BookListSerializer
class WritableNestedSerializer(serializers.ModelSerializer):
# This is my implementation for nested writes.
def update(self, instance, validated_data):
# Here I need to do logic for the saving of books.
# I want to reuse the instances filled in already, like with a
foreign key, which get fetched based on the id field in their
validated_data.
# Otherwise I need to do a query for every id in the validated_data
of this serializer, whilst it already has been done.
for field in validated_data:
if field == relational: # Simplified if check.
data = validated_data.pop(field)
instance_list = self.fields[field].save(data) #
This calls the save of my custom list serializer.
return super(WritableNestedSerializer, self).update(**kwargs)
class AuthorSerializer(WritableNestedSerializer):
# Example author serializer with a relation to books.
books = BookSerializer(many=True)
I would expect a ListSerializer to have some kind of list in it with it's
children (or values).
It seems the ListSerializer reuses a single child for everything?
Also why isn't the ListSerializer not instantiated with data automatically
so you can call the save, validated_data etc.?
But my main question is: how would I get this to work without adding a
bunch of queries?
Thanks in advance for any help!
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