Snippet

Dynamic Method Composition on Custom Django QuerySets

Using Python multiple inheritance within a factory function allows dynamically composing distinct custom Django `QuerySet` subclasses into a unified model `Manager` instance.

snippet.py

python

from django.db import models
 
class SoftDeleteQuerySet(models.QuerySet):
    def active(self):
        return self.filter(is_deleted=False)
 
class AuditQuerySet(models.QuerySet):
    def verified(self):
        return self.filter(is_verified=True)
 
def compose_querysets(*queryset_classes):
    class ComposedQuerySet(*queryset_classes):
        pass
    return ComposedQuerySet.as_manager()

django

Breakdown

class SoftDeleteQuerySet(models.QuerySet):

Defines specialized reusable query filtering logic on a QuerySet subclass.

class ComposedQuerySet(*queryset_classes):

Dynamically constructs a combined QuerySet class via multiple inheritance.

return ComposedQuerySet.as_manager()

Converts the composed QuerySet class into a standard Django Manager factory.

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Dynamic Method Composition on Custom Django QuerySets

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