How to query for documents by searching for a value in an array?

Question

So using the three documents below as examples

[
  {
    _id: '/players/c/cruzne02.shtml',
    url: '/players/c/cruzne02.shtml',
    name: 'Nelson Cruz',
    image: 'https://www.baseball-reference.com/req/202108020/images/headshots/f/fea2f131_mlbam.jpg',
    teams: {
      MIL: [ 2005 ],
      TEX: [
        2006, 2007, 2007, 2008,
        2008, 2009, 2009, 2010,
        2010, 2011, 2011, 2012,
        2012, 2013, 2013
      ],
      BAL: [ 2014 ],
      SEA: [
        2015, 2016,
        2016, 2017,
        2017, 2018,
        2018
      ],
      MIN: [ 2019, 2020, 2020, 2021, 2021 ],
      TBR: [ 2021 ]
    }
  },
  {
    _id: '/players/b/berrijo01.shtml',
    url: '/players/b/berrijo01.shtml',
    name: 'Jose Berrios',
    image: 'https://www.baseball-reference.com/req/202108020/images/headshots/d/d94db113_mlbam.jpg',
    teams: {
      MIN: [
        2016, 2017, 2017,
        2018, 2018, 2019,
        2019, 2020, 2020,
        2021, 2021
      ],
      TOR: [ 2021 ]
    }
  },
  {
    _id: '/players/m/mauerjo01.shtml',
    url: '/players/m/mauerjo01.shtml',
    name: 'Joe Mauer',
    image: 'https://www.baseball-reference.com/req/202108020/images/headshots/4/43c69595_mlbam.jpg',
    teams: {
      MIN: [
        2004, 2005, 2005, 2006, 2006,
        2007, 2007, 2008, 2008, 2009,
        2009, 2010, 2010, 2011, 2011,
        2012, 2012, 2013, 2013, 2014,
        2014, 2015, 2015, 2016, 2016,
        2017, 2017, 2018, 2018
      ]
    }
  }
]

For example if I want to query for someone who played for team MIN in 2016 I want to get the second and third document. But if I queried for 2020 in the MIN array I would get the first and second documents returned. I'm trying to get players from a certain team for that year and I'm not sure how to structure my find to get the results I'm looking for.

I tried using

db.Players.find({teams:{MIN: {$elemMatch: 2021}}});

but it doesn't return anything. Am I using the $elemMatch wrong?

Answer 1

The teams field is an object and not an array, which I believe is why $elemMatch isn't working, because it is an array operator.

If you want to use $elemMatch, you could try a query like this, which specifies teams.MIN, which is an array:

db.Players.find({ "teams.MIN" : { $elemMatch: { $eq: 2021 }}});

But because this is an example of an $elemMatch with a single query condition, it would be simpler to do it like this:

db.Players.find({ "teams.MIN" : 2021 });