Django，访问 model 方法

Question

In the Django documentation, they recommend writing business logic in Model.

How do the View layer or queryset access the methods in Model?

As per example in documentation ( https://docs.djangoproject.com/en/3.0/topics/db/models/ )

from django.db import models

class Person(models.Model):
    first_name = models.CharField(max_length=50)
    last_name = models.CharField(max_length=50)
    birth_date = models.DateField()

    def baby_boomer_status(self):
        "Returns the person's baby-boomer status."
        import datetime
        if self.birth_date < datetime.date(1945, 8, 1):
            return "Pre-boomer"
        elif self.birth_date < datetime.date(1965, 1, 1):
            return "Baby boomer"
        else:
            return "Post-boomer"

How do view layer access the baby_boomer_status ?

I have a little experienced in Django development but I used to write logics in View itself.

Answer 1

You can just call the method on the person instance:

person = Person.objects.get(id=1)
print(person.baby_boomer_status())

Answer 2

You can iterate over QuerySet and call the model method as

for person in Person.objects.all():
    print(person.baby_boomer_status())

If you have a single object, just call the method directly as,

print(Person.objects.get(pk=123).baby_boomer_status())

Answer 3

This can be done by simply calling function. For example,

>>> from .models import Person
>>> person = Person.objects.get(id=1) # Remember getting the person object
>>> person.baby_boomer_status()

You have to first get person object otherwise, it will return function itself, eg

>>> from .models import Person
>>> person.baby_boomer_status()
>>> <function AppName.models.Person.baby_boomer_status(self)>