How to search in array of object in mongodb

javascript arrays node.js mongodb express
vcxz picture vcxz · Dec 26, 2012 · Viewed 155.1k times · Source

Suppose the mongodb document(table) 'users' is

{
  _id: 1,
  name: { first: 'John', last: 'Backus' },
  birth: new Date('Dec 03, 1924'),
  death: new Date('Mar 17, 2007'),
  contribs: [ 'Fortran', 'ALGOL', 'Backus-Naur Form', 'FP' ],
  awards: [
            { award: 'National Medal',
              year: 1975,
              by: 'NSF' },
            { award: 'Turing Award',
              year: 1977,
              by: 'ACM' }
          ]
}
and other object(person)s

I want to find the person who has the award 'National Medal' and must be awarded in year 1975 There could be other persons who have this award in different years.

How can I find this person using award type and year. So I can get exact person.

Answer

Leonid Beschastny picture Leonid Beschastny · Dec 26, 2012

The right way is:

db.users.find({awards: {$elemMatch: {award:'National Medal', year:1975}}})

$elemMatch allows you to match more than one component within the same array element.

Without $elemMatch mongo will look for users with National Medal in some year and some award in 1975s, but not for users with National Medal in 1975.

See MongoDB $elemMatch Documentation for more info. See Read Operations Documentation for more information about querying documents with arrays.

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