How do I make and access regex capture groups in Django without RawSQL? (https://stackoverflow.com/questions/59198776/how-do-i-make-and-access-regex-capture-groups-in-django-without-rawsql/59252836#59252836)

admin.py

from django.contrib.admin import ModelAdmin, register
from django.db.models import IntegerField
from django.db.models.functions import Cast
from django.db.models.expressions import Func, Value

from .models import Foo


class RegexpMatches(Func):
    function = 'REGEXP_MATCHES'

    def __init__(self, source, regexp, flags=None, group=None, output_field=None, **extra):
        template = '%(function)s(%(expressions)s)'

        if group:
            if not hasattr(regexp, 'resolve_expression'):
                regexp = Value(regexp)

            template = '({})[{}]'.format(template, str(group))

        expressions = (source, regexp)
        if flags:
            if not hasattr(flags, 'resolve_expression'):
                flags = Value(flags)

            expressions += (flags,)

        self.template = template

        super().__init__(*expressions, output_field=output_field, **extra)


@register(Foo)
class Foo(ModelAdmin):
    list_display = ['id', 'required_field', 'required_field_string']

    def get_queryset(self, request):
        qs = super().get_queryset(request)

        return qs.annotate(
            required_field=Cast(RegexpMatches('id', r'^(.*\D)([0-9]*)$', group=2), output_field=IntegerField()),
            required_field_string=RegexpMatches('id', r'^(.*\D)([0-9]*)$', group=2)
        )

    def required_field(self, obj):
        return obj.required_field

    def required_field_string(self, obj):
        return obj.required_field_string

models.py

from django.db import models


class Foo(models.Model):
    id = models.CharField(primary_key=True, max_length=100)

    def __str__(self):
        return self.id