Metadata-Version: 2.1
Name: django-fieldsignals
Version: 0.7.0
Summary: Django fieldsignals simply makes it easy to tell when the fields on your model have changed.
Home-page: https://github.com/craigds/django-fieldsignals
Author: Craig de Stigter
Author-email: craig.ds@gmail.com
License: UNKNOWN
Description: [![Build Status](https://travis-ci.org/craigds/django-fieldsignals.svg?branch=master)](https://travis-ci.org/craigds/django-fieldsignals)
        
        # Introduction
        
        django-fieldsignals simply makes it easy to tell when the fields on your model have changed.
        
        Often model updates are quite expensive. Sometimes the expensive operations
        are very rare. This makes it tempting to put the update logic in a view,
        rather than in a save() method or in a signal receiver:
        
        ```python
            # A bad example. Don't do this!
            def edit_poll(request, poll_id):
        
                # ...
        
                if form.cleaned_data['poll_name'] != poll.name:
                    poll.update_slug(form.cleaned_data['poll_name'])
                poll.save()
        ```
        
        That's a bad idea, because your model consistency is now dependent on your view.
        
        Instead, use django-fieldsignals:
        
        ```python
            from fieldsignals import pre_save_changed
        
            def update_poll_slug(sender, instance, **kwargs):
                instance.slug = slugify(instance.name)
        
            pre_save_changed.connect(update_poll_slug, sender=Poll, fields=['name'])
        ```
        
        
        In case you want to know what changed, django-fieldsignals even tells you the old and
        new values of your fields:
        
        ```python
            from fieldsignals import pre_save_changed
        
            def print_all_field_changes(sender, instance, changed_fields, **kwargs):
                for field, (old, new) in changed_fields.items():
                    print(f'{field.name} changed from {old} to {new}')
        
            pre_save_changed.connect(print_all_field_changes, sender=Poll)
        ```
        
        # Installation
        
        1. This library is on PyPI so you can install it with:
        
        ```bash
            pip install django-fieldsignals
        ```
        
        or from github:
        
        ```bash
            pip install 'git+https://github.com/craigds/django-fieldsignals.git#egg=django-fieldsignals'
        ```
        
        2. Add `"fieldsignals"` to your `INSTALLED_APPS` setting like this:
        
        ```python
            INSTALLED_APPS = (
                ...
                'fieldsignals',
            )
        ```
        
        3. Add some signals!
        
        # Where should my signals code live?
        
        Field signals must be connected after the django apps are ready.
        So putting signal connectors at the bottom of your models file, or other random places won't work.
        
        The best place to connect fieldsignals is an [`AppConfig.ready()` handler](https://docs.djangoproject.com/en/1.11/ref/applications/#for-application-authors).
        
        # Notes
        
        * Currently no support for `ManyToManyField` or reverse side of `ForeignKey` (one to many).
        
Platform: UNKNOWN
Classifier: Environment :: Web Environment
Classifier: Framework :: Django
Classifier: Intended Audience :: Developers
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
Classifier: Programming Language :: Python :: 3.8
Classifier: Programming Language :: Python :: 3.9
Classifier: Topic :: Internet :: WWW/HTTP
Classifier: Topic :: Internet :: WWW/HTTP :: Dynamic Content
Description-Content-Type: text/markdown
