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Extended QuerySets for Django

Project description

ExtendedQuerySets

ExtendedQuerySets is meant to simplify the way to retrieve one object from db using Django QuerySets.

Installation:

$ pip install extquerysets

Examples:

For the following examples assume that we have a model Player, and we've implemented custom Manager and QuerySet for that model.

Task 1: Retrieve one object or return None if object doesn't exist.

Usual way:

try:
   winner = Player.objects.winner()
except Player.DoesNotExist:
   winner = None

Using ExtendedQuerySets:

winner = Player.objects.winner_or_none()

Task 2: Retrieve one object or raise Http404 if object doesn't exist.

Usual way:

try:
   winner = Player.objects.winner()
except Player.DoesNotExist:
   raise Http404

Using ExtendedQuerySets:

winner = Player.objects.winner_or_404()

Usage:

models.py

from django.db import models

from .querysets import PlayerQuerySet


class Player(model.Model):
    name = models.CharField(_('Name'), max_length=12)
    is_winner = models.BooleanField(_('Is winner'), default=False)
    
    objects = PlayerQuerySet.as_manager()

querysets.py

from extquerysets.base import CustomQuerySet
from extquerysets.decorators import or_404
from extquerysets.decorators import or_none


class PlayerQuerySet(CustomQuerySet):
    @or_404
    @or_none
    def get(self, *args, **kwargs):
        return super().get(*args, **kwargs)

    @or_404
    @or_none
    def winner(self):
        return self.get(is_winner=True)

Now you can retrieve Player instance:

from .models import Player

...

player = Player.objects.winner_or_none()
player = Player.objects.winner_or_404()
player = Player.objects.filter(name__icontains='Tom').winner_or_none()
player = Player.objects.filter(name__icontains='Tom').winner_or_404()
player = Player.objects.get_or_none(pk=10)
player = Player.objects.get_or_404(pk=10)

...

More info about custom Managers and QuerySets: https://docs.djangoproject.com/en/2.0/topics/db/managers/

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