Terrible Things

example_code.py

class UUIDIdMixin(models.Model):
    class Meta:
        abstract = True

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)


class Body(UUIDIdMixin):
    name = models.CharField(max_length=140)
    description = models.CharField(max_length=280)
    data = JSONField(blank=True, null=True)

    def __str__(self):
        return "Body {} - {}".format(self.pk, self.name)


class Crater(UUIDIdMixin):
    TYPES = {'int': int,
             'float': float,
             'str': str}

    body = models.ForeignKey(Body)
    data = JSONField(blank=True, null=True)


class CratersFilter(django_filters.FilterSet):
    data = django_filters.MethodFilter(action='filter_data')

    class Meta:
        model = models.Crater
        fields = ['id', 'body']

    def filter_data(self, queryset, value):
        keys = value.split("~!@!~")
        filters = [tuple(key.split(":")) for key in keys]
        for f in filters:
            if len(f) > 3:
                field, field_type, value, lookup_type = f
            else:
                field, field_type, value = f
                lookup_type = None
            field_type = self.Meta.model.TYPES.get(field_type)
            if field_type is not None:
                value = field_type(value)
                if lookup_type is not None:
                    query_arg = 'data__{}__{}'.format(field, lookup_type)
                else:
                    query_arg = 'data__{}'.format(field)
                del lookup_type
                kwargs = {query_arg: value}
                queryset = queryset.filter(**kwargs)
        return queryset