I'm basically using $all operator in mongo and the input i get might be array or single element as following. So how do use underscore to put all the elements in one array and then
userId = 'a';
userIds = ['a', 'b', 'c'];
otherId = ['a'] or 'a';
searchArray = [userId, userIds, otherId]
db.collections.find({userIds: {$all: searchArray}})