drf-auto-query

Auto generate Django ORM query sets from serializers.

Installation

$ pip install drf-auto-query

Description

The "drf-auto-query" package addresses the common problem of N+1 queries in Django ORM when building REST framework endpoints. It provides convenient helper functions and mixins to assist in generating efficient QuerySet objects tailored to your specific serializer requirements.

It is important to note that while "drf-auto-query" aims to alleviate the N+1 problem, it is not a comprehensive solution. Instead, it serves as a valuable tool to be used in conjunction with your own efforts to write efficient queries. By automating the process of prefetching related data, the package helps reduce the number of database queries required, resulting in improved performance and responsiveness for your Django-based APIs, while it also speeds up development because you will not have to worry about your serializer setup firing unwanted database queries.

Usage

Prefetch function

The prefetch_queryset_for_serializer function streamlines the process of setting up the necessary prefetch_related and select_related calls on a QuerySet based on a given serializer class.

from rest_framework import serializers
from drf_auto_query import prefetch_queryset_for_serializer

from my_app.models import UserGroup


class UserSerializer(serializers.Serializer):
    id = serializers.IntegerField()
    username = serializers.CharField()
    email = serializers.EmailField()

    
class UserGroupSerializer(serializers.Serializer):
    id = serializers.IntegerField()
    name = serializers.CharField()
    users = UserSerializer(many=True)
    
    
queryset = UserGroup.objects.all()
queryset = prefetch_queryset_for_serializer(queryset, UserGroupSerializer)

QuerySet mixin

The AutoQuerySetMixin offers a convenient way to automatically prefetch the required relations on a QuerySet.

from django.db import models

from drf_auto_query.mixins import AutoQuerySetMixin


class MyModelQuerySet(AutoQuerySetMixin, models.Model):
    ...
    
    
class MyModel(models.Model):
    ...
    
    objects = models.Manager.from_queryset(MyModelQuerySet)()

This can then be used in a class based view.

from rest_framework import generics

from my_app.models import MyModel
from my_app.serializers import MyModelSerializer


class MyModelList(generics.ListAPIView):
    serializer_class = MyModelSerializer
    queryset = MyModel.objects.prefetch_for(serializer_class)

Using the both the mixin and the prefetch function ensures that any annotations, joins, or other modifications to the QuerySet are preserved while automatically prefetching the necessary data for efficient serialization.

⚠️ Any multi-nested prefetches that have altered querysets might be overwritten. This is a known issue and will be addressed in a future release.

Example of a multi-nested prefetch:

MyModel.objects.prefetch_related(
    Prefetch(
        'my_related_model',
        queryset=MyRelatedModel.objects.prefetch_related(
            Prefetch(
                'my_other_related_model',
                # This queryset might not be preserved.
                queryset=MyOtherRelatedModel.objects.annotate(count_something=Count('something'))
            )
        )
    )
)

MyModel.objects.prefetch_related(
    Prefetch(
        'my_related_model__my_other_related_model',
        # This will be preserved.
        queryset=MyOtherRelatedModel.objects.annotate(count_something=Count('something'))
    )
)

Contributing

Interested in contributing? Check out the contributing guidelines. Please note that this project is released with a Code of Conduct. By contributing to this project, you agree to abide by its terms.

License

drf-auto-query was created by Jakob Verlic. It is licensed under the terms of the MIT license.