What's the correct way to use helpers to extend functionality in Django models?

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I'm adding some extended functionallity to my models in Django. In order to not overload the model root interface (and file), i'm using some helpers as attributes of the model.

What i want is to group the methods and properties into this helpers, and what i want is something like:

class Product(models.Model):
    downloads = DownloadsHelper()
    # ....
    pass

p = Product.objects.first()
p.downloads.files_count(p)
p.downloads.reset_permissions(p)
# ...

In order to not to have to pass the instance to the helper each time, I could use another approach.

class Product(models.Model):
    def __init__(self, *args, **kwargs):
        super(Product, self).__init__(*args, **kwargs)
        self.downloads = DownloadsHelper(self)
        self.shipping = ShippingHelper(self)

p = Product.objects.first()
p.downloads.files_count
p.downloads.reset_permissions()

And finally, a more python-generic/conceptual way to do this stuff would be like:


class Helper:
    def __init__(self, helped):
        self.helped = helped

class Helper1(Helper):
    attribute_name = 'helloing'

    def hola(self): print("hola")


class Helper2(Helper):
    attribute_name = 'goodbying'

    def chau(self): print("chau")


class Helped:
    def __init__(self):
        self._install_helpers()

    def _install_helpers(self):
        for helper in self.helpers:
            setattr(self, helper.attribute_name, helper(self))

class MyHelped(Helped):
    helpers = [Helper1, Helper2]

h = MyHelped()
h.helloing.hola()
h.goodbying.chau()

And the question is: Is this last approach a correct way /good practice to do the stuff from a pythonic-OOP and "Djangoid" point of view. Has this any problem?

Thanks for reading!

helper oop django-models django python
1 Answers

Maybe you did not show the full complexity for your methods, but from what you showed it could be simplified a bit.

You could use "direct/simple" inheritance, and if you have a lot of methods then for organization you could maybe prefix the method names with h1_ and h2_ to indicate which helper class they are from:

from django.db import models

class Helper1:
    def h1_hola(self):
        print("hola")

class Helper2:
    def h2_chau(self):
        print("chau")

class MyHelped(Helper1, Helper2, models.Model):
    pass

h = MyHelped()
h.h1_hola()
h.h2_chau()

Would this simpler approach be sufficient for your specific needs?

user_92256710
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