How can one search for ndb models based on key inequality?
For example, for a string one can use:
def add_inequality_filter(query, attr, given)
end = given + u'\ufffd'
return query.filter(attr >= given, attr < end)
add_inequality_filter(query, "key", "abc.")
If key were an ordinary string property this would work, however the key is a ModelKey.
Comparing the key (or _key) to a string triggers a BadValueError.
There does not appear to be a documented way to create a ModelKey (or equivalent) for comparison.
When I try to filter on __key__ > (the db way) I get a Cannot filter a non-Node argument.
The db to ndb documentation certainly indicates that this should be possible.
