Django-filter BaseInFilter

Question

I am currently trying to use BaseInFilter. Users can input the ids separated by commas like the one shown in the picture. I want to make a validator(or regulate user's input) so that the user can only input integers here.

If the user enters characters, the Django backend will throw out this error.

I have also tried this:

class BaseIntegerFilter(filters.BaseInFilter, filters.NumberFilter):
    pass

class HardwareFilter(filters.FilterSet):
    queryset = Hardware
    serializer_class = HardwareSerializer
    id = filters.BaseIntegerFilter(field_name="id", label="Comma separated list of hardware IDs", help_text="Comma separated list of hardware IDs")

But this solution doesn't allow me to input commas in the textbox anymore.

Could anyone help? Any help will be really appreatiated!

Answer 1

Here is some guidance with regards to usage.

Using filterset_class with BaseInFilter

• https://django-filter.readthedocs.io/en/stable/guide/rest_framework.html#adding-a-filterset-with-filterset-class
• https://django-filter.readthedocs.io/en/stable/ref/filters.html#baseinfilter
• Note that the parameters queryset and serializer_class are fields of view classes, not filter classes.

views.py:

from django_filters.rest_framework import DjangoFilterBackend
from rest_framework import viewsets

from my_app.filters import MyFilter
from my_app.models import MyModel
from my_app.serializers import MySerializer


class MyViewSet(viewsets.ModelViewSet):
    queryset = MyModel.objects.all()
    serializer_class = MySerializer
    filter_backends = [DjangoFilterBackend]
    filterset_class = MyFilter
    lookup_field = 'id'

filters.py:

from django_filters.rest_framework import BaseInFilter, FilterSet, NumberFilter

from my_app.models import MyModel


class _NumberInFilter(BaseInFilter, NumberFilter):
    pass


class MyFilter(FilterSet):
    id__in = _NumberInFilter(field_name='id', lookup_expr='in')

    class Meta:
        model = MyModel
        fields = '__all__'

HTTP request (numbers):

$ curl http://127.0.0.1:8000/my_app/my_view_set/?id__in=2,5,6
[{"id":5,"name":"Some name 5"},{"id":2,"name":"Some name 2"},{"id":6,"name":"Some name 6"}]

• Note that the lookup in the query parameter was id__in and not just id.
• curl was used here. For easier access, you can also enter it in a browser, Postman, etc.

HTTP request (numbers and letters):

$ curl http://127.0.0.1:8000/my_app/my_view_set/?id__in=2,5FD,6
{"id__in":["Enter a number."]}

Using filterset_fields

• https://django-filter.readthedocs.io/en/stable/guide/rest_framework.html#using-the-filterset-fields-shortcut
• https://django-filter.readthedocs.io/en/stable/guide/usage.html#generating-filters-with-meta-fields
• https://django-filter.readthedocs.io/en/stable/ref/filterset.html#declaring-filterable-fields
• django Rest Framework filter by date range

views.py:

from django_filters.rest_framework import DjangoFilterBackend
from rest_framework import viewsets

from my_app.models import MyModel
from my_app.serializers import MySerializer


class MyViewSet(viewsets.ModelViewSet):
    queryset = MyModel.objects.all()
    serializer_class = MySerializer
    filter_backends = [DjangoFilterBackend]
    filterset_fields = {'id': ['in']}
    lookup_field = 'id'

HTTP request:

• Same as with filterset_class

---

UI rendering error

The HTTP requests performed above are manual, without using the UI provided by djangorestframework. Upon trying it with the UI, I experienced the same problem as you stated:

But this solution doesn't allow me to input commas in the textbox anymore.

This is not related to the filtering mechanism provided by django_filters (which happens in the backend) as this is a pure frontend issue specifically with the form validation.

A manual workaround I did was inspect the textbox (right-click + inspect) then update the HTML line from number to text. So from:

<input type="number" name="id__in" step="any" id="id_id__in">

To:

<input type="text" name="id__in" step="any" id="id_id__in">

HTTP Request (numbers):

HTTP request (numbers and letters):

You may want to intercept the actual rendering of the HTML by the djangorestframework or django_filters to do this cleanly.