How to invalidate @cached_property in django

How to invalidate @cached_property in django

In Django, the @cached_property decorator is used to create a cached property on a class. The property's value is computed once and then cached for subsequent access. If you need to invalidate or clear a cached property, you can do so by setting its value to None, forcing the property to be recomputed the next time it's accessed.

Here's an example of how you can invalidate a @cached_property in Django:

from django.utils.functional import cached_property from django.db import models class MyModel(models.Model): @cached_property def expensive_computation(self): # Simulate an expensive computation print("Computing...") return sum(range(1000000)) # Create an instance of MyModel obj = MyModel() # Access the cached property (this will compute and cache the result) print(obj.expensive_computation) # Now, invalidate the cached property by setting it to None obj.expensive_computation = None # Access the cached property again (this will recompute and cache the result) print(obj.expensive_computation)

In this example, the @cached_property decorator is used to create a cached property called expensive_computation. When you access the property, it performs an expensive computation and caches the result. If you set the property to None, it will be invalidated, and the next access will trigger a recomputation.

Keep in mind that manually invalidating cached properties might be necessary in certain cases, but it can also affect performance. Be sure to consider the trade-offs and carefully manage caching depending on your application's requirements.

Examples

  1. "How to invalidate Django cached property in view?"

    Description: You can invalidate a Django @cached_property in a view by setting its value to None, forcing it to be recalculated the next time it's accessed.

    class MyView(View): @cached_property def my_cached_property(self): # Calculate the value here return some_value def my_view_method(self, request): # Invalidate the cached property self.my_cached_property = None # Access the property to recalculate its value value = self.my_cached_property

  2. "How to clear Django cached property on model save?"

    Description: You can clear a Django @cached_property when a model is saved by overriding the save() method of the model and setting the property to None.

    class MyModel(models.Model): @cached_property def my_cached_property(self): # Calculate the value here return some_value def save(self, *args, **kwargs): # Call the parent save method super().save(*args, **kwargs) # Invalidate the cached property self.my_cached_property = None

  3. "How to invalidate Django cached property in admin?"

    Description: You can invalidate a Django @cached_property in the admin interface by overriding the save_model() method of the admin class and setting the property to None.

    class MyModelAdmin(admin.ModelAdmin): def save_model(self, request, obj, form, change): # Call the parent save_model method super().save_model(request, obj, form, change) # Invalidate the cached property obj.my_cached_property = None

  4. "Using signals to invalidate Django cached property"

    Description: You can use signals, such as pre_save, to invalidate a Django @cached_property when certain conditions are met.

    from django.db.models.signals import pre_save from django.dispatch import receiver @receiver(pre_save, sender=MyModel) def invalidate_cached_property(sender, instance, **kwargs): # Invalidate the cached property instance.my_cached_property = None

  5. "How to reset Django cached property on user logout?"

    Description: You can reset a Django @cached_property when a user logs out by listening to the user_logged_out signal.

    from django.contrib.auth.signals import user_logged_out from django.dispatch import receiver @receiver(user_logged_out) def invalidate_cached_property_on_logout(sender, user, **kwargs): # Invalidate the cached property for the user user.my_cached_property = None

  6. "Invalidating Django cached property on related model changes"

    Description: You can invalidate a Django @cached_property when related model instances are changed by listening to signals such as post_save or post_delete.

    from django.db.models.signals import post_save, post_delete from django.dispatch import receiver @receiver([post_save, post_delete], sender=RelatedModel) def invalidate_cached_property_on_related_change(sender, instance, **kwargs): # Invalidate the cached property instance.my_model.my_cached_property = None

  7. "How to manually expire Django cached property?"

    Description: You can manually expire a Django @cached_property by implementing a method to set its value to None when needed.

    class MyModel(models.Model): @cached_property def my_cached_property(self): # Calculate the value here return some_value def expire_cached_property(self): # Invalidate the cached property self.my_cached_property = None

  8. "Using custom management command to invalidate Django cached property"

    Description: You can create a custom management command to invalidate a Django @cached_property when necessary, allowing administrators to manually trigger the invalidation.

    from django.core.management.base import BaseCommand from myapp.models import MyModel class Command(BaseCommand): def handle(self, *args, **options): # Invalidate the cached property MyModel.my_cached_property = None self.stdout.write(self.style.SUCCESS('Cached property invalidated successfully'))

  9. "How to reset Django cached property on specific user actions?"

    Description: You can reset a Django @cached_property based on specific user actions by incorporating the reset logic into views or forms.

    class MyView(View): def my_view_method(self, request): # Process the view logic # Invalidate the cached property based on specific user actions if some_condition: request.user.my_cached_property = None

  10. "Clearing Django cached property cache manually"

    Description: You can clear the cache of a Django @cached_property manually by accessing the property's cache and deleting its value.

    class MyModel(models.Model): @cached_property def my_cached_property(self): # Calculate the value here return some_value # Manually clear the cache del MyModel().my_cached_property

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