Mongo find documents that do not contain a given value (using $not)

Question

I have two items in MongoDB:

{\'title\':\'active item\',
 \'tags\':[
        {\'tag\':\'active\'},
        {\'tag\':\'anothertag\'}
]}
{\'title\':\'completed         


        

Answer 1

You can do it with $ne operator.

db.items.find({"tags.tag" : {$ne : "completed"}})

Answer 2

The target of the $not operator needs to be an operator-expression, not a field/value object.

So parvin's answer is the easiest way to do this, but just for learning purposes, you can do this with $not by using $not supported expressions like:

db.items.find({tags: {$not: {$elemMatch: {tag: 'completed'}}}})

db.items.find({'tags.tag': {$not: /completed/}})