Django models: is it possible to force icontains on filter/get for specific field using a manager?

Question

Let's say I have a model with a string field similar to this

class Product(models.Model):
    upc = models.CharField(max_length=12, blank=False, null=False)

Is it possible to build a model manager or something similar where every time I use Product.objects.get/Product.objects.filter it overrides the default lookup to force the search/filter to behave like I had used icontains?

As in:

Product.objects.get(upc="012345678902")
Product.objects.filter(upc="012345678902")

By default would behave like:

Product.objects.get(upc__icontains="012345678902")
Product.objects.filter(upc__icontains="012345678902")

Answer 1

You can custom a query manager or queryset, and override the get/filter method. The demo below can tell you how to custom a query manager implements force icontains.

from django.db import models


class ForceIContainsManager(models.Manager):
    force_icontains_fields = None

    def __init__(self, *args, **kwargs) -> None:
        if "force_icontains_fields" in kwargs:
            self.force_icontains_fields = kwargs.pop("force_icontains_fields")
        super(ForceIContainsManager, self).__init__(*args, **kwargs)

    def get(self, *args, **kwargs):
        kwargs = self._force_icontains(**kwargs)
        return super(ForceIContainsManager, self).get(*args, **kwargs)

    def filter(self, *args, **kwargs):
        kwargs = self._force_icontains(**kwargs)
        return super(ForceIContainsManager, self).filter(*args, **kwargs)

    def _force_icontains(self, **kwargs):
        """
        replace field in force_icontains_fields to icontains style
        """
        if not self.force_icontains_fields:
            return kwargs
        for field in self.force_icontains_fields:
            if field in kwargs:
                v = kwargs.pop(field)
                new_field_name = '%s__icontains' % field
                kwargs[new_field_name] = v
        return kwargs


class YourModel(models.Model):
    # define a another manager, YourModel.manager will force icontains on certain fields
    manager = ForceIContainsManager(
        force_icontains_fields=["field1", "field2"])
    # if you want use YourModel.objects, you should uncomment below
    # objects = ForceIContainsManager(force_icontains_fields=["field1", "field2"])
    pass


# check sql
print(YourModel.manager.filter(field1='test').query)

More customize can see https://sodocumentation.net/django/topic/1400/custom-managers-and-querysets

QueryManager has proxy all method in QuerySet by BaseManager.from_queryset, choose one is enought.