findOneAndUpdate

[steevej (Steeve Juneau)]

@NestorDaza

That works beautifully

But but. I returned to the original post and original query. And it also works wonderfully. Yes the following

@Lasse_Johansen

{"$expr" : { "$lt": [{ "$size": "$users" }, "$package.maxUserCount"] }}

So I felt in the same trap I felt before, that is, assuming that there was a real problem other than typos in field names and/or missing $ in some field names. In the first post, package.maxUserCount was missing the $ but that was corrected promptly. I should also have requested sample documents. Perhaps the discrepancy is between the field name

@Lasse_Johansen

package.maxUserCount

or the text requirement

@Lasse_Johansen

users array size is less than maxUserCount

I tried different typos variations and the one that

@Lasse_Johansen

returns true on any document

is the one where the $ sign is missing in front of package.maxUserCount. When the dollar sign is present with a non existing field name the query is false for all documents.