{
    "_id" : ObjectId("50ed90a55502684f440001ac"),
    "time" : "2020-05-14T14:12:46.058-0400",
    "ServerTimeStamp" : "2020-05-14T14:12:46.058-0400"

}

{
    "_id" : ObjectId("50ed90a55502684f440001advert"),
    "time" : "2020-05-14T15:12:46.058-0400",
    "ServerTimeStamp" : "2020-05-14T14:12:46.058-0400"
}

{
    "_id" : ObjectId("50ed90a55502684f440001ae"),
    "time" : "2020-05-14T18:12:46.058-0400",
    "ServerTimeStamp" :"2020-05-14T14:12:46.058-0400"
}

I wish to calculate the time distinction of above rows ( in seconds) as beneath . right here the time discipline is in string format as an alternative of datetime

{

    "_id" : ObjectId("50ed90a55502684f440001ac"),
    "time" : "2020-05-14T14:12:46.058-0400",
    "time_difference" :null
}

{
    "_id" : ObjectId("50ed90a55502684f440001advert"),
    "time" : "2020-05-14T15:12:46.058-0400",
    "time_difference" : 3600  
}

{
    "_id" : ObjectId("50ed90a55502684f440001ae"),
    "time" : "2020-05-14T18:12:46.058-0400",
    "time_difference" : 10800
}

I attempted the beneath question however getting error and i’ve already transformed the time thus far from string

db.hey.combination(
    {$kind: {$dateFromString:{time: 1}}},
    {$group: {_id: 0, doc: {$push: '$$ROOT'}}},
    {$venture: {documentAndPrevTime: {$zip: {inputs: ['$document', {$concatArrays: [[null], '$doc.time']}]}}}},
    {$unwind: {path: '$documentAndPrevTime'}},
    {$replaceWith: {$mergeObjects: [{$arrayElemAt: ['$documentAndPrevTime', 0]}, {prevTime: {$arrayElemAt: ['$documentAndPrevTime', 1]}}]}},
    {$set: {time_difference: {$trunc: [{$divide: [{$subtract: ['$time', '$prevTime']}, 1000]}]}}},
    {$unset: 'prevTime'}
);