Natural sort on Django Queryset

Question

I am working on a system that lists out a range of products sorted by their product code. The product codes are made up of two letters for the followed by a number, for exam

Answer 1

I think the implementation here (https://github.com/nathforge/django-naturalsortfield) should work. The main advantage of this method is that it doesn't do the sorting in python but in the database so it'll perform well even on large datasets, at the cost of some additional storage.

You have to change your model to include a product_code__sort field

class MyModel(models.Model):
    title = models.CharField(max_length=255)
    title_sort = NaturalSortField('title')

where the NaturalSortField is defined as

class NaturalSortField(models.CharField):
    def __init__(self, for_field, **kwargs):
        self.for_field = for_field
        kwargs.setdefault('db_index', True)
        kwargs.setdefault('editable', False)
        kwargs.setdefault('max_length', 255)
        super(NaturalSortField, self).__init__(**kwargs)

    def pre_save(self, model_instance, add):
        return self.naturalize(getattr(model_instance, self.for_field))

    def naturalize(self, string):
        def naturalize_int_match(match):
            return '%08d' % (int(match.group(0)),)

        string = string.lower()
        string = string.strip()
        string = re.sub(r'^the\s+', '', string)
        string = re.sub(r'\d+', naturalize_int_match, string)

        return string

Answer 2

Try this

def alphanumeric_sort(objects_list, sort_key):
    """ Sort a list of objects by a given key
    This function sort a list of objects by a given
    key common across the objects
    Sorting can be implemented on keys that are either
    alphabets, integers or both
    """
    convert = lambda text: int(text) if text.isdigit() else text
    alphanum_key = lambda key: [
        convert(c) for c in re.split("([0-9]+)", getattr(key, sort_key))
    ]
    return sorted(objects_list, key=alphanum_key)