How to access array elements in mongodb

Question

hello i am new to mongodb syntax i achived the result below using a query:

   {
    "_id" : "abc",
    "info" : [ 
        {
            "user_status" : true,
            "timeActive" : 2.0
        }, 
        {
            "user_status" : false,
            "timeActive" : 1.0
        }
    ]
}

the data in by database is given below

/* 1 */
{
    "_id" : ObjectId("60f25f41f6d12949670676e4"),
    "user_id" : "xyz",
    "from_time" : 12.0,
    "to_time" : 13.0,
    "status" : true
}

/* 2 */
{
    "_id" : ObjectId("60f25f41f6d12949670676e5"),
    "user_id" : "xyz",
    "from_time" : 13.0,
    "to_time" : 14.0,
    "status" : false
}

/* 3 */
{
    "_id" : ObjectId("60f25f41f6d12949670676e6"),
    "user_id" : "xyz",
    "from_time" : 14.0,
    "to_time" : 15.0,
    "status" : true
}

/* 4 */
{
    "_id" : ObjectId("60f25f41f6d12949670676e7"),
    "user_id" : "xyz",
    "from_time" : 15.0,
    "to_time" : 17.0,
    "status" : false
}

/* 5 */
{
    "_id" : ObjectId("60f27483f6d12949670676e8"),
    "user_id" : "abc",
    "from_time" : 15.0,
    "to_time" : 17.0,
    "status" : true
}

/* 6 */
{
    "_id" : ObjectId("60f27483f6d12949670676e9"),
    "user_id" : "abc",
    "from_time" : 17.0,
    "to_time" : 18.0,
    "status" : false
}

the query i used is

db.users.aggregate(
[
    {$match:{ status_to_time : {$ne:null} }},
    {$set:{totalTime:   {$subtract:["$status_to_time" , "$status_from_time"]} }},
    
    {$group:{_id:{user_id:"$information_id" , user_status:"$status"} , allSum:{$sum:"$totalTime"} }},
    
    
    
   {$project:{"user_id":"$_id.user_id" ,"user_status":"$_id.user_status" , timeA:"$allSum",_id:0}},
    
    {$sort:{user_id:1 , user_status:-1}},
    
    {$group:{_id:"$user_id" , info:{$push:{user_status:"$user_status" , timeActive:"$timeA"}} }},]
    )

but i also want to to achieve division as info[0].timeActive / info[1].timeActive in a parmeter timeDiv so my final result of query should be

    {
        "_id" : "abc",
        "info" : [ 
            {
                "user_status" : true,
                "timeActive" : 2.0
            }, 
            {
                "user_status" : false,
                "timeActive" : 1.0
            }
        ]
timeDiv:2 // division as info[0].timeActive / info[1].timeActive
    }

please someone answer how to achieve that

Thanks for your response i got my answer but i am providing my data here in case it help any one else the data is given now in my question — Daniyal
– Daniyal, Commented Aug 1, 2021 at 6:17

Rubén Vega · Accepted Answer · 2021-07-31 18:56:03Z

1

You could use $addField, $divide and $arrayElemAt like this: playground.

Just add this aggregation at the end of your query and you should get the expected result.

edited Jul 31, 2021 at 18:56

answered Jul 31, 2021 at 18:36

Rubén Vega

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2 Comments

Rubén Vega Over a year ago

However, be carefull with the object index positions and 0, null values, etc

Daniyal Over a year ago

Thanks for your answer you solved my problem

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