Django ORM Sugar

Sugar library to simplify Django querying

Installation

pip install django-orm-sugar

Overview

The updated Q object replaces calls like

SomeModel.objects.filter(user__profile__common_bucket__seq_count__gte=7)

With more pythonic syntax

from django_orm_sugar import Q

SomeModel.objects.filter(Q.user.profile.common_bucket.seq_count >= 7)

It gets easy to follow DRY principles when working with long query paths

from django_orm_sugar import Q

# saving reference for QFactory
seq_count = Q.user.profile.common_bucket.seq_count

# using it multiple times - in filter and order_by calls
SomeModel.objects.filter(seq_count >= 7).order_by(seq_count.get_path())

It is still possible to create Q objects in the old style way:

q = Q(user__profile__common_bucket__seq_count=1)

Queries

Comparison operators

General comparison operators generate related Q objects:

>>> Q.user.username == 'Bender Rodriguez'
Q(user__username='Bender Rodriguez')

>>> Q.user.age > 7
Q(user__age__gt=7)

>>> Q.user.age >= 7
Q(user__age__gte=7)

>>> Q.user.age < 7
Q(user__age__lt=7)

>>> Q.user.age <= 7
Q(user__age__lte=7)

Filter by null (or not-null) fields

>>> Q.user.favorite_movie.is_null()
Q(user__favorite_movie__isnull=True)

>>> Q.user.favorite_movie.is_null(False)
Q(user__favorite_movie__isnull=False)

Filter by fields matching a given list

>>> Q.user.id.in_list([1, 2, 3])
Q(user__id__in=[1, 2, 3])

Common Django filter shortcuts

>>> Q.user.username.iexact('Bender Rodriguez')
Q(user__username__iexact='Bender Rodriguez')

>>> Q.user.username.exact('Bender Rodriguez')
Q(user__username__exact='Bender Rodriguez')

>>> Q.user.username.contains('Rodriguez')
Q(user__username__contains='Rodriguez')

>>> Q.user.username.icontains('Rodriguez')
Q(user__username__icontains='Rodriguez')

Index and slices queries

Used by PostgreSQL ArrayField or JSONField

>>> Q.data.owner.other_pets[0].name='Fishy'
Q(data__owner__other_pets__0__name='Fishy')

>>> Q.tags[0] == 'thoughts'
Q(tags__0='thoughts')

>>> Q.tags[0:2].contains(['thoughts']) 
Q(tags__0_2__contains=['thoughts'])

Passing multiple arguments

It's possible to pass multiple arguments, they will be converted to tuple in final expression.

>>> Q.user.create_datetime.range(d1, d2)
Q(user__create_datetime__range=(d1, d2))

However, passing them as tuple is also allowed as a single argument will be passed to lookup expression without any modifications.

Get query path as string with underscores

It's useful for order_by, select_related and other calls, which expect query path as string

>>> Q.user.username.get_path()
'user__username'

Extending

It's possible to register custom helpers. Let's say it's required to create in_exc_range() helper, which will perform exclusive range filtering.

from django_orm_sugar import register_helper

# write helper function and register it using special decorator
@register_helper('in_exc_range')
def exclusive_in_range_helper(query_path, min_value, max_value):
    """
    Unlike existing in_range method, filtering will be performed
    excluding initial values. In other words - we will use "<" and ">"
    comparison instead of "<=" and ">="
    """
    q_gt = Q(**{'{}__gt'.format(query_path): min_value})
    q_lt = Q(**{'{}__lt'.format(query_path): max_value})
    return q_gt & q_lt

The actual function name doesn't matter, only passed name to decorator does. Now a newly registered helper can be used:

>>> Q.user.registration_date.in_exc_range(from_date, to_date)
Q(registration_date__gt=from_date) & Q(registration_date__lt=to_date)