Quickstart

django-dirtyfields is a small library for tracking dirty fields on a Django model instance. Dirty means that a field’s in-memory value is different to the saved value in the database.

Installation

$ pip install django-dirtyfields

Usage

To use django-dirtyfields, you need to:

• Inherit from the DirtyFieldsMixin class in the Django model you want to track dirty fields.

from django.db import models
from dirtyfields import DirtyFieldsMixin

class ExampleModel(DirtyFieldsMixin, models.Model):
    """A simple example model to test dirtyfields with"""
    characters = models.CharField(max_length=80)

• Use one of these 2 functions on a model instance to know if this instance is dirty, and get the dirty fields:

  • is_dirty()

  • get_dirty_fields()

Example

>>> model = ExampleModel.objects.create(characters="first value")
>>> model.is_dirty()
False
>>> model.get_dirty_fields()
{}
>>> model.characters = "second value"
>>> model.is_dirty()
True
>>> model.get_dirty_fields()
{'characters': 'first_value'}

Why would you want this?

When using django.db.models.signals (django.db.models.signals.pre_save especially), it is useful to be able to see what fields have changed or not. A signal could change its behaviour depending on whether a specific field has changed, whereas otherwise, you only could work on the event that the model’s save() method had been called.