repository·master·Indexed 22 days ago
https://github.com/beda-software/drf-writable-nestedA Django REST Framework extension that enables writable nested model serializers. It allows the creation and update of complex object graphs in a single API call, supporting OneToOne, ForeignKey, ManyToMany, and GenericRelation relationship types. The library provides the WritableNestedModelSerializer class and UniqueFieldsMixin to handle unique field validation during the save stage.
The library supports the following relationship types for nested creation and updates:
through model).To allow creating or updating models with related nested data, inherit from WritableNestedModelSerializer. You must define the nested serializers for the related fields within your main serializer.
Example of defining a nested structure:
from drf_writable_nested.serializers import WritableNestedModelSerializer
class ProfileSerializer(WritableNestedModelSerializer):
# Direct ManyToMany relation
sites = SiteSerializer(many=True)
# Reverse FK relation
avatars = AvatarSerializer(many=True)
# Direct FK relation
access_key = AccessKeySerializer(allow_null=True)
class Meta:
model = Profile
fields = ('pk', 'sites', 'avatars', 'access_key',)from rest_framework import serializers
from drf_writable_nested.serializers import WritableNestedModelSerializer
class AvatarSerializer(serializers.ModelSerializer):
image = serializers.CharField()
class Meta:
model = Avatar
fields = ('pk', 'image',)
class SiteSerializer(serializers.ModelSerializer):
url = serializers.CharField()
class Meta:
model = Site
fields = ('pk', 'url',)
class AccessKeySerializer(serializers.ModelSerializer):
class Meta:
model = AccessKey
fields = ('pk', 'key',)
class ProfileSerializer(WritableNestedModelSerializer):
# Direct ManyToMany relation
sites = SiteSerializer(many=True)
# Reverse FK relation
avatars = AvatarSerializer(many=True)
# Direct FK relation
access_key = AccessKeySerializer(allow_null=True)
class Meta:
model = Profile
fields = ('pk', 'sites', 'avatars', 'access_key',)
class UserSerializer(WritableNestedModelSerializer):
# Reverse OneToOne relation
profile = ProfileSerializer()
class Meta:
model = User
fields = ('pk', 'profile', 'username',)To run the unit tests, follow these steps to set up a virtual environment and execute pytest:
# Setup the virtual environment
python3 -m venv envname
source envname/bin/activate
pip install django
pip install django-rest-framework
pip install -r requirements.txt
# Run tests
py.testWhen updating nested serializers that contain unique fields, standard DRF validation may fail. Use UniqueFieldsMixin to move UniqueValidator from the validation stage to the save stage.
Important Rules:
UniqueFieldsMixin only to the serializer that contains the unique fields.UniqueFieldsMixin must be placed ahead of NestedCreateMixin or NestedUpdateMixin in the inheritance list.class ChildSerializer(UniqueFieldsMixin, NestedUpdateMixin, serializers.ModelSerializer):
class Meta:
model = Child
class ParentSerializer(NestedUpdateMixin, serializers.ModelSerializer):
child = ChildSerializer()
class Meta:
model = Parentclass Child(models.Model):
field = models.CharField(unique=True)
class Parent(models.Model):
child = models.ForeignKey('Child')
class ChildSerializer(UniqueFieldsMixin, serializers.ModelSerializer):
class Meta:
model = Child
class ParentSerializer(NestedUpdateMixin, serializers.ModelSerializer):
child = ChildSerializer()
class Meta:
model = ParentInstall the package using pip to enable writable nested model serializers in your Django REST Framework project.
pip install drf-writable-nestedUpdating nested fields via form-data in PUT or PATCH requests is currently unsupported by DRF and this library (e.g., using voucherrows[1].account=... syntax).
Solution: Instead of sending array fields as separate form-data keys, send the entire nested array as a single JSON string. Then, in your view, parse that JSON string back into a Python object before passing it to the serializer.
Example Implementation:
import json
class VoucherViewSet(viewsets.ModelViewSet):
serializer_class = VoucherSerializer
queryset = serializer_class.Meta.model.objects.all().order_by('-created_at')
def update(self, request, *args, **kwargs):
# Parse the 'voucherrows' field from a JSON string into a list/dict
request.data.update({
'voucherrows': json.loads(request.data.pop('voucherrows', None))
})
return super().update(request, *args, **kwargs)# From your views you need to parse it like below before sending it to the serializer
class VoucherViewSet(viewsets.ModelViewSet):
serializer_class = VoucherSerializer
queryset = serializer_class.Meta.model.objects.all().order_by('-created_at')
def update(self, request, *args, **kwargs):
request.data.update({'voucherrows': json.loads(request.data.pop('voucherrows', None))})
return super().update(request, *args, **kwargs)Once your WritableNestedModelSerializer is defined, you can pass nested dictionaries or lists in the data argument to .is_valid() and .save(). The serializer will automatically handle the creation/update of all nested relations.
data = {
'username': 'test',
'profile': {
'access_key': {
'key': 'key',
},
'sites': [
{'url': 'http://google.com'},
{'url': 'http://yahoo.com'},
],
'avatars': [
{'image': 'image-1.png'},
{'image': 'image-2.png'},
],
},
}
user_serializer = UserSerializer(data=data)
user_serializer.is_valid(raise_exception=True)
user = user_serializer.save()data = {
'username': 'test',
'profile': {
'access_key': {
'key': 'key',
},
'sites': [
{
'url': 'http://google.com',
},
{
'url': 'http://yahoo.com',
},
],
'avatars': [
{
'image': 'image-1.png',
},
{
'image': 'image-2.png',
},
],
},
}
user_serializer = UserSerializer(data=data)
user_serializer.is_valid(raise_exception=True)
user = user_serializer.save()You can pass a dictionary of values to the base serializer's save() method. These values will be passed down to the nested serializers. Note that the same value will be used for all nested instances as a default, but with higher priority than existing defaults.
# user_serializer created with 'data' as above
user = user_serializer.save(
profile={
'access_key': {'key': 'key2'},
},
)
print(user.profile.access_key.key) # Output: 'key2'# user_serializer created with 'data' as above
user = user_serializer.save(
profile={
'access_key': {'key': 'key2'},
},
)
print(user.profile.access_key.key)