Query against a non-empty array with a specific value

Question

Query against a non-empty array with a specific value

for example

> db.test.insert( { 'a':5 } )
> db.test.insert( { 'a': [5] } )

> db.test.find({ 'a':5})
{ "_id" : ObjectId("53e2b4366c9ef5cceb327e01"), "a" : 5 }
{ "_id" : ObjectId("53e2b43b6c9ef5cceb327e02"), "a" : [ 5 ] }

But I only want to be able to match the first document.

+3

mongodb mongodb-query

smartnut007 06 Aug 14 at 23:05

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1 answer

Neil lunn · Answer 1 · 2014-08-06T23:14:47+0000

The easiest way is to check for the existence of an array element using and "dot notation": $exists

db.test.find({ "a": 5, "a.0": { "$exists": false } })

Says that "a" is 5, but the first array element in "a" cannot exist.

Query against a non-empty array with a specific value

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