在创建不同的 model 对象时，如何选择性地指定 django model 字段值？

Question

I have the following models in my django app:

from django.db import models

class TaskTracking(models.Model):
    name = models.CharField(max_length=20)

class Parent(models.Model):
    my_attribute = models.CharField(max_length=255, blank=True)
    my_attribute2 = models.CharField(max_length=255, blank=True)


class Child(Parent):
    tracking = models.ForeignKey(TaskTracking, on_delete=models.PROTECT)

Then I have another file where I am trying to make instances of these two models. What I intend to do is invoke the create method, based on a parameter, something like this:

from .models import *

class BaseObjectCreator:
    model = Parent
    def createModelObject(trackingEnabled=False):
        tracking_instance = None

        if trackingEnabled:
             tracking_instance = TaskTracking.objects.create(name='Dummy name')

        instance = self.model.objects.create(
                   my_attribute = 'value1',
                   my_attribute = 'value2',
                   tracking = tracking_instance if trackingEnabled
                   )

class ChildObjectCreator:
    model = Child
    def createModelObject(trackingEnabled=True):
        super().createModelObject(trackingEnabled)

But this is not working and throwing error for this line tracking = tracking_instance if trackingEnabled . I need something like this for refactoring a large code which involves models like the ones defined above. Can you suggest the correct strategy?

PS - The tracking attribute of the Child model is an FK hence NOT NULL constraint is implied.

Answer 1

There's another strategy to tackle this. You could go about it in this manner:

from .models import *

class BaseObjectCreator:
    model = Parent
    def createModelObject(trackingEnabled=False):
        instance = self.model.objects.create(
                   my_attribute = 'value1',
                   my_attribute = 'value2',
                   )
        if (trackingEnabled):
            instance.tracking = 'value3'
            instance.save()

class ChildObjectCreator:
    model = Child
    def createModelObject(trackingEnabled=True):
        super().createModelObject(trackingEnabled)

I am not aware if there's a way to invoke conditional statements inline. But this seems like a clean enough solution.