Function _slice_head

ormar/queryset/utils.py:187–209

Handles ``Model.objects[:N]`` — the first ``N`` rows of the result set. Negative ``stop`` would mean "everything except the last ``|N|`` rows", which needs a ``COUNT(*)`` to resolve, so it is rejected. Examples:: [:5] → SliceBounds(limit=5, offset=0, reverse=False)

(stop: int)

def _slice_head(stop: int) -> SliceBounds:
    """
    Handles ``Model.objects[:N]`` — the first ``N`` rows of the result set.
    Negative ``stop`` would mean "everything except the last ``|N|`` rows",
    which needs a ``COUNT(*)`` to resolve, so it is rejected.

    Examples::

        [:5]  → SliceBounds(limit=5, offset=0, reverse=False)
        [:0]  → SliceBounds(limit=0, offset=0, reverse=False)
        [:-2] → raises QueryDefinitionError

    :param stop: upper bound from the slice
    :type stop: int
    :return: ``SliceBounds(limit=stop, offset=0, reverse=False)``
    :rtype: SliceBounds
    """
    if stop < 0:
        raise QueryDefinitionError(
            "Negative slice stop without a start requires an explicit count; "
            "use .count() with .offset()/.limit() instead."
        )
    return SliceBounds(limit=stop, offset=0, reverse=False)


def _slice_tail(start: int) -> SliceBounds: