Mongoose find returns document instead of specific object in array

Question

When I try to find specific object in array using find({query}) I always get all elements from array. Activities array stores activities (it would be a thousands of them) as you can see in the following snippet:

This is my collection:

{
    "_id" : ObjectId("58407140755324d04db2ce95"),
    "owner" : 103429326776572,
    "activities" : [
            {
                    "name" : "test1",
                    "startTime" : ISODate("2016-08-11T17:41:54Z"),
                    "type" : "te1",
                    "lat" : 1,
                    "lon" : 1,
                    "creator" : 126212904493088,
                    "coverPhoto" : {
                            "name" : "test1",
                            "path" : "c:\\Users\\Francis\\Desktop\\dusk\\public\\coverPhotos\\SJ9tpP6Mx.jpg"
                    },
                    "identifier" : "H1g9F6vpGl",
                    "users" : [
                            1,
                            2,
                            3
                    ],
                    "hashTags" : [
                            "some",
                            "hashtags"
                    ]
            },
            {
                    "name" : "test2",
                    "startTime" : ISODate("2016-08-11T17:41:53Z"),
                    "type" : "te2",
                    "lat" : 1,
                    "lon" : 1,
                    "creator" : 103312904493090,
                    "coverPhoto" : {
                            "name" : "test2",
                            "path" : "c:\\Users\\Francis\\Desktop\\dusk\\public\\coverPhotos\\Hy8qpvafe.jpg"
                    },
                    "identifier" : "rJlU5TvpMx",
                    "users" : [
                            1,
                            2,
                            3
                    ],
                    "hashTags" : [
                            "some",
                            "hashtags"
                    ]
            }
    ]

}

I need to get for example an activity that has specific identifier. I tried to use queries like:

1) db.myCollection.find({'activities.identifier' : "rJlU5TvpMx"})

2) db.myCollection.find({'activities' : { $elemMatch : { "identifier" : "rJlU5TvpMx", "creator" : 103312904493090 } })

And all combinations with '' or "" signs

I found above queries at mongodb docs in equal documents schema as mine is.

Can you tell me what am I doing wrong ?

Answer 1

You can try either use single match or multiple match based on your need. This makes use of $elemMatch(projection)

db.myCollection.find({"_id" : ObjectId("58407140755324d04db2ce95")},
             {activities: {$elemMatch: { identifier: "rJlU5TvpMx"}}})

db.myCollection.find( {"_id" : ObjectId("58407140755324d04db2ce95")},
             {activities: {$elemMatch: {creator : 103312904493090, identifier: "rJlU5TvpMx" }}})

Answer 2

You are looking for the projection object which gets passed as an argument in your query. It allows the return of specific fields from your search rather than the entire document. http://mongoosejs.com/docs/api.html#model_Model.find

I would also suggest looking at the response to this question here: Mongoose Query: Find an element inside an array which makes use of the unwind operator to enter the array as it seems to be relevant to your needs.

Answer 3

In the collection you are searching in, you have just one Document(Object). If you apply method find() to your collection and the query inside matches the value in activities.identifier it will return the only Document(object).

To have a better understanding of what I am talking about check example on mongoose API doc And query result here .

Try check this out https://docs.mongodb.com/v3.0/reference/operator/projection/elemMatch/#proj._S_elemMatch instead