We currently support $expand=navProp/$count to return just the count of the nav prop.
We also support $expand=navProp($count=true) to return the nav prop and the count.
We support $select=prop($count=true).
We support prop/$count in a filter ($filter=collectionProp/$count gt 5)
We don't seem to support $select=prop/$count or $select=prop/$count(...)

It seems like we should.

Proposal: Support the same /$count functionality for $select as we support for $expand.

collectionProp/$count
collectionProp/$count($filter....)

Resolved as proposed 2025-2-5

If the type contains a lot of properties, Is there any simple way to get all properties but for a certain collection properties, only get the number, so, we don't want to list all other properties within $select.

For example, can we do like:

$select=*,ColProp/$count

I believe the above would return all properties (including ColProp) plus the count of ColProp.

In general, we don't have a way to except individual properties in the select (or expand) list. We could introduce something like -propName, so you could do $select=*,-ColProp, ColProp/$count.

2025-2-12: We discussed omitting the counted properties. If we want to omit the counted property, we should do it through a generic method that omits properties. Such a mechanism should be handled separate from this issue.

There did not seem to be an expressed need in pursuing such a mechanism at this time.