django-rest-framework-sideloading | Django rest framework | REST library

You need to define the primary serializer in the Meta data and can define prefetching rules. Also notice the many=True on the sideloadable relationships. For fields where the source is provided or where the source matches the field name, prefetches are not strictly required. Multiple prefetches can be added to a single sideloadable field, but when using Prefetch object check that they don't clash with prefetches made in the get_queryset() method. Multiple sources can be added to a field using a dict. Each key is a source_key that can be used to filter what sources should be sideloaded. The values set the source and prefetches for this source. Note that this prefetch reuses primary_supplier and secondary_suppliers if suppliers and primary_supplier or secondary_suppliers are sideloaded. Usage of Prefetch() objects is supported. Prefetch() objects can be used to filter a subset of some relations or just to prefetch or select complicated related objects In case there are prefetch conflicts, to_attr can be set but be aware that this prefetch will now be a duplicate of similar prefetches. prefetch conflicts can also come from prefetched made in the ViewSet.get_queryset() method. Note that this prefetch noes not reuse primary_supplier and secondary_suppliers if suppliers and primary_supplier or secondary_suppliers are sideloaded at the same time.
Install drf-sideloading: pip install drf-sideloading
Import SideloadableRelationsMixin: from drf_sideloading.mixins import SideloadableRelationsMixin
Write your SideLoadableSerializer: You need to define the primary serializer in the Meta data and can define prefetching rules. Also notice the many=True on the sideloadable relationships. from drf_sideloading.serializers import SideLoadableSerializer class ProductSideloadableSerializer(SideLoadableSerializer): products = ProductSerializer(many=True) categories = CategorySerializer(source="category", many=True) primary_suppliers = SupplierSerializer(source="primary_supplier", many=True) secondary_suppliers = SupplierSerializer(many=True) suppliers = SupplierSerializer(many=True) partners = PartnerSerializer(many=True) class Meta: primary = "products" prefetches = { "categories": "category", "primary_suppliers": "primary_supplier", "secondary_suppliers": "secondary_suppliers", "suppliers": { "primary_suppliers": "primary_supplier", "secondary_suppliers": "secondary_suppliers", }, "partners": "partners", }
Prefetches For fields where the source is provided or where the source matches the field name, prefetches are not strictly required Multiple prefetches can be added to a single sideloadable field, but when using Prefetch object check that they don't clash with prefetches made in the get_queryset() method from django.db.models import Prefetch prefetches = { "categories": "category", "primary_suppliers": ["primary_supplier", "primary_supplier__some_related_object"], "secondary_suppliers": Prefetch( lookup="secondary_suppliers", queryset=Supplier.objects.prefetch_related("some_related_object") ), "partners": Prefetch( lookup="partners", queryset=Partner.objects.select_related("some_related_object") ) } Multiple sources can be added to a field using a dict. Each key is a source_key that can be used to filter what sources should be sideloaded. The values set the source and prefetches for this source. Note that this prefetch reuses primary_supplier and secondary_suppliers if suppliers and primary_supplier or secondary_suppliers are sideloaded prefetches = { "primary_suppliers": "primary_supplier", "secondary_suppliers": "secondary_suppliers", "suppliers": { "primary_suppliers": "primary_supplier", "secondary_suppliers": "secondary_suppliers" } } Usage of Prefetch() objects is supported. Prefetch() objects can be used to filter a subset of some relations or just to prefetch or select complicated related objects In case there are prefetch conflicts, to_attr can be set but be aware that this prefetch will now be a duplicate of similar prefetches. prefetch conflicts can also come from prefetched made in the ViewSet.get_queryset() method. Note that this prefetch noes not reuse primary_supplier and secondary_suppliers if suppliers and primary_supplier or secondary_suppliers are sideloaded at the same time. from django.db.models import Prefetch prefetches = { "categories": "category", "primary_suppliers": "primary_supplier", "secondary_suppliers": "secondary_suppliers", "suppliers": { "primary_suppliers": Prefetch( lookup="secondary_suppliers", queryset=Supplier.objects.select_related("some_related_object"), to_attr="secondary_suppliers_with_preselected_relation" ), "secondary_suppliers": Prefetch( lookup="secondary_suppliers", queryset=Supplier.objects.filter(created_at__gt=pendulum.now().subtract(days=10)).order_by("created_at"), to_attr="latest_secondary_suppliers" ) }, }
Configure sideloading in ViewSet: Include SideloadableRelationsMixin mixin in ViewSet and define sideloading_serializer_class as shown in example below. Everything else stays just like a regular ViewSet. Since version 2.0.0 there are 3 new methods that allow to overwrite the serializer used based on the request version for example from drf_sideloading.mixins import SideloadableRelationsMixin class ProductViewSet(SideloadableRelationsMixin, viewsets.ModelViewSet): """ A simple ViewSet for viewing and editing products. """ queryset = Product.objects.all() serializer_class = ProductSerializer sideloading_serializer_class = ProductSideloadableSerializer def get_queryset(self): # Add prefetches for the viewset as normal return super().get_queryset().prefetch_related("created_by") def get_sideloading_serializer_class(self): # use a different sideloadable serializer for older version if self.request.version < "1.0.0": return OldProductSideloadableSerializer return super().get_sideloading_serializer_class() def get_sideloading_serializer(self, *args, **kwargs): # if modifications are required to the serializer initialization this method can be used. return super().get_sideloading_serializer(*args, **kwargs) def get_sideloading_serializer_context(self): # Extra context provided to the serializer class. return {"request": self.request, "format": self.format_kwarg, "view": self}
Enjoy your API with sideloading support Example request and response when fetching all possible values GET /api/products/?sideload=categories,partners,primary_suppliers,secondary_suppliers,suppliers,products { "products": [ { "id": 1, "name": "Product 1", "category": 1, "primary_supplier": 1, "secondary_suppliers": [2, 3], "partners": [1, 2, 3] } ], "categories": [ { "id": 1, "name": "Category1" } ], "primary_suppliers": [ { "id": 1, "name": "Supplier1" } ], "secondary_suppliers": [ { "id": 2, "name": "Supplier2" }, { "id": 3, "name": "Supplier3" } ], "suppliers": [ { "id": 1, "name": "Supplier1" }, { "id": 2, "name": "Supplier2" }, { "id": 3, "name": "Supplier3" } ], "partners": [ { "id": 1, "name": "Partner1" }, { "id": 2, "name": "Partner1" }, { "id": 3, "name": "Partner3" } ] } The user can also select what sources to load to Multi source fields. Leaving the selections empty or omitting the brackets will load all the prefetched sources. Example: GET /api/products/?sideload=suppliers[primary_suppliers] { "products": [ { "id": 1, "name": "Product 1", "category": 1, "primary_supplier": 1, "secondary_suppliers": [2, 3], "partners": [1, 2, 3] } ], "suppliers": [ { "id": 1, "name": "Supplier1" } ] }