Can the Django ORM store an unsigned 64-bit integer (aka ulong64 or uint64) in a reliably backend-agnostic manner?

Question

All the docs I\'ve seen imply that you might be able to do that, but there isn\'t anything official w/r/t ulong64/uint64 fields. There are a few off-the-shelf options t

Answer 1

Although I did not test it, but you may wish to just subclass BigIntegerField. The original BigIntegerField looks like that (source here):

class BigIntegerField(IntegerField):
    empty_strings_allowed = False
    description = _("Big (8 byte) integer")
    MAX_BIGINT = 9223372036854775807

    def get_internal_type(self):
        return "BigIntegerField"

    def formfield(self, **kwargs):
        defaults = {'min_value': -BigIntegerField.MAX_BIGINT - 1,
                    'max_value': BigIntegerField.MAX_BIGINT}
        defaults.update(kwargs)
        return super(BigIntegerField, self).formfield(**defaults)

Derived PositiveBigIntegerField may looks like this:

class PositiveBigIntegerField(BigIntegerField):
    empty_strings_allowed = False
    description = _("Big (8 byte) positive integer")

    def db_type(self, connection):
        """
        Returns MySQL-specific column data type. Make additional checks
        to support other backends.
        """
        return 'bigint UNSIGNED'

    def formfield(self, **kwargs):
        defaults = {'min_value': 0,
                    'max_value': BigIntegerField.MAX_BIGINT * 2 - 1}
        defaults.update(kwargs)
        return super(PositiveBigIntegerField, self).formfield(**defaults)

Although you should test it thoroughly, before using it. If you do, please share the results :)

EDIT:

I missed one thing - internal database representation. This is based on value returned by get_internal_type() and the definition of the column type is stored eg. here in case of MySQL backend and determined here. It looks like overwriting db_type() will give you control over how the field is represented in the database. However, you will need to find a way to return DBMS-specific value in db_type() by checking connection argument.