Django Duplicate

Django-Duplicate has an util tool for making a deep copy of django model instances

duplicate.utils.duplicate

Creates and returns a new object that is identical to instance.

DuplicateMixin

Mixin for model classes which implements duplicate function as method.

from django.db import models

from duplicate.models import DuplicateMixin


class Book(DuplicateMixin, models.Model):
    title = models.CharField(max_lenght=100)
    author = models.ForegnKey('library.Author')

Let's duplicate (shallow copy) book instance:

book = Book(title='Two Scoops of Django')
boook.save()

book_copy = book.duplicate()

If you wanna do deep (related models gonna be shallow copied) copy use paths argument of duplicate method. paths should be list of relation paths:

book_copy = book.duplicate(paths=['author'])

To shallow copy every relation on some level use * symbol:

book_copy = book.duplicate(paths=['*'])

author.* path would copy also all author relations.

There is also symbol ~ which means "reference relations, but if reference object is duplicated in the context use it instead".

You can override fields like this(You cannot override nested m2m fields):

book_copy = book.duplicate(paths=['author'], override_fields={'author.name': 'Overriden author name'})


from duplicate.utils import CallableValue
book_copy = book.duplicate(paths=['author'], override_fields={'author.name': 'Overriden author name'})

You can also override nested fields with callable that takes instace on which you are overriding field as an argument:

from duplicate.utils import CallableValue

book_copy = book.duplicate(
    paths=['author'],
    override_fields={
        'author.name': CallableValue(lambda author: 'Professional author name' if author.professional else 'Author name')
    }
)

DJANGO_DUPLICATE_KNOWN_RELATIONS

To ensure that code is aware of all possible to duplicate models and relations path project should have setting DJANGO_DUPLICATE_KNOWN_RELATIONS which is a dict with model labels as keys and list of model relations as value:

DJANGO_DUPLICATE_KNOWN_RELATIONS = {
    "duplicate.Author": [
        "book_set",
    ],
    "duplicate.Book": [
        "author",
    ],
}

This app enables check which will throw errors when state of app will not correspond to value of DJANGO_DUPLICATE_KNOWN_RELATIONS.

License

The Django Wicked Historian package is licensed under the FreeBSD License.