CODEWITHSUNDEEP
pythondjangomodel
Dzejkob
Dzejkob

Reputation: 2442

Implementing required interfaces in abstract parent model class in Django

I've defined a base abstract model class which gives some extra funcionality to the model, like this:

class BaseModel(models.Model):
    # ... some fields and methods
    class Meta:
        abstract = True

class Model1(BaseModel):
    # ... some fields and methods
    def required_method(self, *args, *kwargs):
        # implementation

class Model2(BaseModel):
    # ... some fields and methods

Now I need to ensure, that each derived class has number of required methods defined. If any of them is not defined, I need to throw an exception on attempt of execution by manage.py. So in other words, BaseModel should require each derived class to define some interfaces, that this BaseModel uses, but not defines by itself.

Where should I implement this checking? Is the __init__ of the BaseModel a good place to check this?

Edit: Purpose of this is just for safety. If somebody or me after some time, will try to inherit from BaseModel class, but forgets to implement required methods, the code will still run until BaseModel code tries to execute any missing method. So it's potentially dangerous to me. It's better to prevent such code from execution. I believe that Java has such mechanism called interfaces. I'd like to do something similar in Python.

Upvotes: 1

Views: 811

Answers (1)

dr. Sybren
dr. Sybren

Reputation: 855

Use the decorators in the abc package to mark which methods should be abstract. The package takes care of the checking for you, so you don't even have to worry about a proper location for your checks ;-)

Upvotes: 2

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