In Mongo DB Getting Whole collection of date even if one is matched inside it

Question

In Mongo DB Getting Whole collection of date even if one is matched inside it.

Creating a new Collection with the below data:

db.details.insert({
    "_id": 1,
    "name": "johnson",
    "dates": [
        {"date": ISODate("2016-05-01")},
        {"date": ISODate("2016-08-01")}
    ]
})

Fetching Back:

db.details.find().pretty()

Output:

{
    "_id": 1,
    "name": "Johnson",
    "dates": [
        {"date": ISODate("2016-05-01T00:00:00Z")},
        {"date": ISODate("2016-08-01T00:00:00Z")}
    ]
}

So here there is a collection called dates inside another collection details.

Now I want to filter the date inside dates using Greater than and want the result showing "2016-08-01".

But when I search like the following:

db.details.find(
    {"dates.date": {$gt: ISODate("2016-07-01")}},
    {"dates.date": 1, "_id": 0}
).pretty()

Getting the Result as below, Its giving me the entire collection even if one date is matched in it:

{
    "dates": [
        {"date": ISODate("2016-05-01T00:00:00Z")},
        {"date": ISODate("2016-08-01T00:00:00Z")}
    ]
}

Please help in getting the Expected data, i.e.:

{
  "date": ISODate("2016-08-01T00:00:00Z")
}

Please use code formatting – tmthydvnprt Jul 26 '16 at 14:30 — tmthydvnprt, Jul 26 '16 at 14:30

score 0 · Accepted Answer · edited Jul 12 '17 at 13:10

You can use aggregate framework for this:

db.details.aggregate([
    {$unwind: '$dates'},
    {$match: {'dates.date': {$gt: ISODate("2016-07-01")}}}, 
    {$project: {_id: 0, 'dates.date': 1}}
]);

Another way (Works only for mongo 3.2):

db.details.aggregate([
    {$project: {
        _id: 0, 
        dates: {
            $filter: {
                input: '$dates', 
                as: 'item', 
                cond: {
                    $gte: ['$$item.date', ISODate('2016-08-01T00:00:00Z')]
                }
            }
        }
    }
}]);

To only return the date field:

db.details.aggregate([
    {$unwind: '$dates'},
    {$match: {'dates.date': {$gt: ISODate('2016-07-01')}}}, 
    {$group: {_id: '$dates.date'}}, 
    {$project: {_id: 0, date: '$_id'}}
]);

Returns:

{ 
  "date" : ISODate("2016-08-01T00:00:00Z") 
}

Thanks for your help, it works perfectly. – giridharan ck Jul 29 '16 at 10:13 — giridharan ck, Jul 29 '16 at 10:13

In Mongo DB Getting Whole collection of date even if one is matched inside it

1 Answers1