Question

I have a collection called season that looks like this:

[ 
  { 
    week: 1,
    matchups: [ 
        {
            home : ObjectId("1"),
            away : ObjectId("2")
        },
        {
            home : ObjectId("3"),
            away : ObjectId("4")
        },

    ],
    _id: 50fc50c9ce87149ee3000007 
  },
  { 
    week: 2,
    matchups: [ 
        {
            home : ObjectId("3"),
            away : ObjectId("1")
        },
        {
            home : ObjectId("2"),
            away : ObjectId("4")
        },
    ],
    _id: 50fc50c9ce87149ee3000008 
  }
]

I’m trying to get all of the matchups where the home OR away team is ObjectId(“1”). I want the return to look like this:

[ 
  { 
    week: 1,
    matchups: [ 
        {
            home : ObjectId("1"),
            away : ObjectId("2")
        }

    ],
    _id: 50fc50c9ce87149ee3000007 
  },
  { 
    week: 2,
    matchups: [ 
        {
            home : ObjectId("3"),
            away : ObjectId("1")
        }
    ],
    _id: 50fc50c9ce87149ee3000008 
  }
]

Is it possible to get this result using on db.season.find()?

Answer 1

As long as you have at most one potential matchups element to match, you can use the $elemMatch projection operator to do this:

db.seasons.find(
    {$or: [{'matchups.home': ObjectId("1")},{'matchups.away': ObjectId("1")}]}, 
    {week: 1, matchups: {
        $elemMatch: {$or: [{home: ObjectId("1")},{away: ObjectId("1")}]}
    }});

Same caveat as Wes regarding the invalidity of ObjectId("1").