django-dunder

django-dunder is an installable app to automatically provide usable __repr__ and __str__ for other Django third-party installable apps and for project apps.

The motivation for this app came while consulting for https://github.com/viper-development/ , which builds apps quickly, developing custom functionality instead of writing boilerplate code.

By default, it will detect and attach to existing models that are using the default __repr__ and __str__.

It can be instructed to overwrite the __repr__ and __str__ of specific models, useful if the model has dedicated methods, but the output is not desirable.

It will look for primary and unique keys, in an attempt to show the minimum necessary for the user to recognise the record.

Install

1. pip install django-dunder
2. Add django_dunder to INSTALLED_APPS before models that need dunders added.

To catch all models missing __str__ or __repr__, put it at the top of INSTALLED_APPS.

To quickly see how it improves the Django admin, install django-data-browser in development before and after, and click its "admin" column on any model that was using the Django default string representation.

Configure

For more control, in your settings, toggle these "auto", "force" and "exclude" settings.

To disable the automatic attaching for one or both of __str__ and __repr__, set one of

• DUNDER_AUTO = False
• DUNDER_AUTO_REPR = False
• DUNDER_AUTO_STR = False

To force all models to use these methods, use DUNDER_FORCE = True, or set DUNDER_FORCE_REPR or DUNDER_FORCE_STR to True.

To force specific models only, DUNDER_FORCE_REPR and DUNDER_FORCE_STR may be defined as a list of model labels, e.g. auth.User.

When using either auto or force modes, specific models can be excluded by providing a list of model labels to the exclude settings:

DUNDER_REPR_EXCLUDE = ['auth.User']
DUNDER_STR_EXCLUDE = ['myapp.Person']

Explicit fields

To show specific fields in either str() or repr(), two extra model meta options are automatically available:

from django.db import models

class MyModel(models.Model):
    uuid = models.TextField()
    first_name = models.TextField()
    last_name = models.TextField()
    ...

    Meta:
        str_fields = ('first_name', 'last_name')
        repr_fields = ('uuid', )

Explicit mixins

Alternatively disable auto mode (DUNDER_AUTO = False), and use the mixins, and set the :

from django_dunder.mixins import DunderModel

class MyModel(DunderModel):
    first_name = models.TextField()
    last_name = models.TextField()
    ...

    Meta:
        repr_fields = ('first_name', 'last_name')

Adding Meta options can cause exceptions if django-dunders is removed from INSTALLED_APPS.

To avoid that, use djsommo

Alternatives

django-dunder is especially useful when a project uses third-party apps that do not provide these dunder methods that are suitable for the project. In fact, several django.contrib models do not provide these dunder methods.

If that is not relevant, and if the project is using sentry, and the project only wants a sane __repr__, incorporate the decorator in sentry.db.models into a base mixin model used throughout the project.

Inspiration was drawn from

• django-model-repr
• django-auto-repr

They may be sufficient for some projects.