CODEWITHSUNDEEP
pythondjango
felix001
felix001

Reputation: 16731

Auto Update Django Model based on other model fields

What is the best method for updating a model field based on the results of another model.

i.e I have the following,

from django.db import models

class ValidateResult(models.Model):
    number = models.IntegerField(unique=True)
    version = models.CharField(max_length=100)

class TotalResult(models.Model):
    total = models.IntegerField()

What I require is TotalResults.total to be a total count of all fields within ValidateResult.number. I want to write this into the model so each time I update the ValidateResults model is auto updates the totals in the TotalResult model.

Any ideas ?

Thanks,

Upvotes: 3

Views: 2640

Answers (1)

Wtower
Wtower

Reputation: 19922

You can use the signals feature:

Django includes a “signal dispatcher” which helps allow decoupled applications get notified when actions occur elsewhere in the framework. In a nutshell, signals allow certain senders to notify a set of receivers that some action has taken place. They’re especially useful when many pieces of code may be interested in the same events.

The django.db.models.signals module predefines a set of signals sent by the model system. You could use the post_save signal which is triggered at the end of a model's save() method.

from django.db.models.signals import pre_save
from django.dispatch import receiver
from myapp.models import MyModel


@receiver(post_save, sender=ValidateResult)
def my_handler(sender, **kwargs):
    ...

Upvotes: 4

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