coady / django-model-values

Django model utilities for encouraging direct data access instead of unnecessary object overhead. Implemented through compatible method and operator extensions to QuerySets and Managers.

The goal is to provide elegant syntactic support for best practices in using Django's ORM. Specifically avoiding the inefficiencies and race conditions associated with always using objects.

Usage

Typical model usage is verbose, inefficient, and incorrect.

book = Book.objects.get(pk=pk)
book.rating = 5.0
book.save()

The correct method is generally supported, but arguably less readable.

Book.objects.filter(pk=pk).update(rating=5.0)

model_values encourages the better approach with operator support.

Book.objects[pk]['rating'] = 5.0

Similarly for queries:

(book.rating for book in books)
books.values_list('rating', flat=True)
books['rating']

Column-oriented syntax is common in panel data layers, and the greater expressiveness cascades. QuerySets also support aggregation and conditionals.

books.values_list('rating', flat=True).filter(rating__gt=0)
books['rating'] > 0

books.aggregate(models.Avg('rating'))['rating__avg']
books['rating'].mean()

Managers provide a variety of efficient primary key based utilities. To enable, instantiate the Manager in your models. As with any custom Manager, it doesn't have to be named objects, but it is designed to be a 100% compatible replacement.

from model_values import Manager

class Book(models.Model):
    ...
    objects = Manager()

F expressions are also enhanced, and can be used directly without model changes.

from model_values import F

.filter(rating__gt=0, last_modified__range=(start, end))
.filter(F.rating > 0, F.last_modified.range(start, end))

Installation

% pip install django-model-values

Tests

100% branch coverage.

% pytest [--cov]

Changes

1.5

• Django >=3.2 required

1.4

• Python >=3.7 required
• Django 4 support

1.3

• Django 3.2 support

1.2

• Python >=3.6 required
• Django >=2.2 required

1.1

• Django 3 support

1.0

• Update related methods moved with deprecation warnings
• Extensible change detection and updates
• Django 2.2 functions

0.6

• Transform functions
• Named tuples
• Window functions
• Distance lookups
• Django 2.1 functions
• EnumField
• Annotated items
• Expressions in column selection

0.5

• F expressions operators any and all
• Spatial lookups and functions
• Django 2.0 support

0.4

• upsert method
• Django 1.9 database functions
• bulk_update supports additional fields

0.3

• Lookup methods and operators
• F expressions and aggregation methods
• Database functions
• Conditional expressions for updates and annotations
• Bulk updates and change detection

0.2

• Change detection
• Groupby functionality
• Named tuples