Signals को Receivers से जोड़ना

एक receiver connect करना bell को किसी का phone number देने जैसा है ताकि इसे पता हो कि बजने पर किसे call करना है।

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एक Receiver Connect करने के दो तरीके
यह सुनिश्चित करना कि Receivers Register हो जाएं
उसी Receiver को कई Senders से Connect करना
एक Receiver Disconnect करना

Syntax

markup

# Decorator
@receiver(signal_name, sender=ModelName)
def handler_name(sender, **kwargs):
    ...

# Manual connect
signal_name.connect(handler_name, sender=ModelName)

एक Receiver Connect करने के दो तरीके

आप एक receiver को @receiver decorator से connect कर सकते हैं, या सीधे signal.connect(func, sender=Model) call करके — दोनों वही चीज़ करते हैं।

उदाहरण: Two Ways to Connect a Receiver

You can connect a receiver with the @receiver decorator, or by calling signal.connect(func, sender=Model) directly — both do the same thing.

markup

from django.dispatch import receiver
from django.db.models.signals import post_delete
from .models import Comment

@receiver(post_delete, sender=Comment)
def log_delete(sender, instance, **kwargs):
    print(f"Comment {instance.pk} deleted")

# Equivalent without the decorator:
# post_delete.connect(log_delete, sender=Comment)

{# Django-only code -- models.py/views.py/urls.py/settings.py snippets, or template markup using Django template tags/variables -- can't run standalone via Judge0 or the browser preview, since it needs a real Django project. Only this course's pure-Python examples (example_lang == 'python', no Django imports) are actually runnable, so those still get the button below. #}

यह सुनिश्चित करना कि Receivers Register हो जाएं

एक receiver सिर्फ तब काम करता है जब Python असल में उस module को import करे जिसमें यह defined है। इसे करने की standard जगह AppConfig.ready() है, जिसे Django startup पर एक बार call करता है।

उदाहरण: Making Sure Receivers Get Registered

A receiver only works if Python actually imports the module it's defined in. The standard place to do this is AppConfig.ready(), which Django calls once at startup.

markup

from django.apps import AppConfig

class BlogConfig(AppConfig):
    default_auto_field = "django.db.models.BigAutoField"
    name = "blog"

    def ready(self):
        import blog.signals

उसी Receiver को कई Senders से Connect करना

एक receiver function एक से ज़्यादा models से connected हो सकता है, या तो connect() कई बार call करके या senders की एक list के ऊपर loop करके।

उदाहरण: Connecting the Same Receiver to Multiple Senders

One receiver function can be connected to more than one model, either by calling connect() several times or looping over a list of senders.

markup

from django.db.models.signals import post_save
from .models import Article, Comment

def log_save(sender, instance, **kwargs):
    print(f"{sender.__name__} saved")

for model in (Article, Comment):
    post_save.connect(log_save, sender=model)

एक Receiver Disconnect करना

Receivers को signal.disconnect() से हटाया जा सकता है, जो mainly tests में उपयोगी है जहां आप temporarily एक side effect को silence करना चाहते हैं।

उदाहरण: Disconnecting a Receiver

Receivers can be removed with signal.disconnect(), which is mainly useful in tests where you want to temporarily silence a side effect.

markup

from django.db.models.signals import post_save
from .signals import log_save
from .models import Article

post_save.disconnect(log_save, sender=Article)

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Signals को Receivers से जोड़ना

एक Receiver Connect करने के दो तरीके

यह सुनिश्चित करना कि Receivers Register हो जाएं

उसी Receiver को कई Senders से Connect करना

एक Receiver Disconnect करना

Chapter Quiz — Complete all 8 topics to unlock

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