Mongodb query. How find the nearest to current date?

Question

I have a collections like this:

{
    "_id" : ObjectId("963fae9d93f4d930c98e269d"),
    "myDate":ISODate("2017-02-05T05:00:00.000Z"),
    "otherData":"blablabla"
},
{
    "_id" : ObjectId("963fae9d93f4d930c98e269d"),
    "myDate":ISODate("2017-02-05T14:00:00.000Z"),
    "otherData":"blablabla"
},
{
    "_id" : ObjectId("963fae9d93f4d930c98e269d"),
    "myDate":ISODate("2017-03-05T02:00:00.000Z"),
    "otherData":"blablabla"
},
{
    "_id" : ObjectId("963fae9d93f4d930c98e269d"),
    "myDate":ISODate("2017-03-05T19:00:00.000Z"),
    "otherData":"blablabla"
}

Given the current date (with minutes and seconds), I want to find the record nearest to the current date (by the "myDate" field).

Thanks

Answer 1

You can subtract the dates in your collection with current date, take the absolute value of the difference to consider for future date and then use sort and limit to get the nearest document:

db.a.aggregate([
{
    $project : {
        myDate : 1,
        otherData : 1,
        difference : {
            $abs : {
                $subtract : [new Date(), "$myDate"]
            }
        }
    }
},
{
    $sort : {difference : 1}
},
{
    $limit : 1
}
])

You can use an additional $project if you want the difference field in the output document. Also instead of current date you can use any other date and find the nearest date to that date.