MongoDB: Find a document by non-existence of a field?

Question

Is there a way to specify a condition of "where document doesn't contain field" ?

For example, I want to only find the first of these 2 because it doesn't have the "price" field.

{"fruit":"apple", "color":"red"}


{"fruit":"banana", "color":"yellow", "price":"2.00"}

Possible duplicate of [Mongo: find items that don't have a certain field](http://stackoverflow.com/questions/5719408/mongo-find-items-that-dont-have-a-certain-field) — Ram Patra, Nov 29 '15 at 08:28

score 373 · Accepted Answer · edited Jun 01 '15 at 13:33

373

Try the $exists operator:

db.mycollection.find({ "price" : { "$exists" : false } })

edited Jun 01 '15 at 13:33

fracz

answered Dec 19 '11 at 21:04

dampier

13

+1. However, keep in mind that such queries can't use indexing and might be very slow on large collections. – mnemosyn Dec 19 '11 at 21:12
11

Great point -- thanks. I know this caveat holds true in MongoDB version 1.8.x and before; but I thought queries with $exists field constraints can now make use of indexes in version 2.0 ...? – dampier Dec 20 '11 at 01:57

1 Answers1