How to I ensure that all items in an $in clause return a match in MongoDB? -

i working set of documents this:

{     name : "bcc 204",      //etc } 

i have list of names want map db entries.

for example:

var names = [ "bcc 204", "stew 101", "smth 123" ] 

and want make query

db.labs.find( { name : { $in: names } } ); 

but $in operator not ensure each item in names array matches result in db.

(more info, names unique)

you can't in query. $in check document matches @ least 1 entry in array given, it's not going consider entire result set. concern you'll need manage in application. given list of inputs, need retrieve results check given_names - results.map(:name) empty.

to put more simply, queries match documents, compose result set - don't match result set.