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Group by arbitrary model fields

Project Description

This package provides a mixin for Django QuerySets that adds a method group_by that behaves mostly like the values method, but with one difference: its iterator does not return dictionaries, but a model-like object with model instances for related values.

Installation

Install from PyPI:

pip install django-group-by

Compatibility

This package is compatible with Django 1.8 and 1.9, and Python versions 2.7, 3.4 and 3.5. Probably others, but those 6 combinations are the ones against which we build (by Travis CI).

Usage

Create a QuerySet subclass with the GroupByMixin to use in a model’s manager:

# models.py

from django.db import models
from django.db.models.query import QuerySet
from django_group_by import GroupByMixin

class BookQuerySet(QuerySet, GroupByMixin):
    pass

class Book(Model):
    objects = BookQuerySet.as_manager()

    title = models.CharField(max_length=100)
    author = models.ForeignKey('another_app.Author')
    publication_date = models.DateField()
...

Then use it just like values, and you’ll get a similar query set:

>>> some_rows = Book.objects.group_by('title', 'author', 'author__nationality').distinct()
>>> some_rows.count()
4

The difference is that every row is not a dictionary but an AggregatedGroup instance, with only the grouped fields:

>>> row = some_rows[0]
>>> row
<AggregatedGroup for Book>
>>> row.title
The Colour of Magic
>>> row.publication_date
*** AttributeError: 'AggregatedGroup' object has no attribute 'publication_date'

But of course the main advantage is that you also get related model instances, as far as you want:

>>> row.author
<Author: Terry Pratchett>
>>> row.author_nationality
<Nation: Great Britain>
Release History

Release History

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0.3.1

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0.3.0

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0.2.2

This version
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0.2.1

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0.2.0

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0.1.1

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0.1.0

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django_group_by-0.2.1-py2.py3-none-any.whl (8.5 kB) Copy SHA256 Checksum SHA256 py2.py3 Wheel May 30, 2016
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