MongoDB: number of matching array elements

Question

I have a collection called "Lines" with the following structure (basically I have a lot of documents containing several arrays, and I need to count their elements with conditions).

    {
        "_id" : "201503110040020021",
        "Line" : "1", // several documents may have this Line value
        "LineStart" : ISODate("2015-03-11T06:49:35.000Z"),
        "SSCEXPEND" : [ 
            {
                "Secuence" : 10,
                "Title" : 1,
            }, 
            {
                "Secuence" : 183,
                "Title" : 613,
            }, 
            ...
        ],
        "SSCCANCELATIONS" : [ 
            {
                "Secuence" : 34,
                "Title" : 113,
            }, 
            {
                "Secuence" : 96,
                "Title" : 2,
            }, 
            ... 
        ],
        "SSCVALIDATIONS" : [ 
            {
                "Secuence" : 12,
                "Result" : 1
            }, 
            {
                "Secuence" : 15,
                "Result" : 1,
            },
            {
                "Secuence" : 18,
                "Result" : 20,
            },
            ...
        ]
    },
    ...

I need to calculate how many elements in these arrays meet certain conditions, for example, I want to count each element from SSCCANCELATIONS, but I only want to count the elements SSCEXPENDusingTitle = 1, and SSCVALIDATIONS elements with Result < 10

I can get the total number of elements of each array,

db.Lines.aggregate( { $project: { Line : 1, Validations: { $size: "$SSCVALIDATIONS" }, ... } } ) 

But I need to stabilize the conditions in order to get something like:

    {
        "_id" : "201503110040020021",
        "Line" : "1",
        "LineStart" : ISODate("2015-03-11T06:49:35.000Z"),
        "SSCEXPEND" : 15,
        "SSCCANCELATIONS" : 10,
        "SSCVALIDATIONS" : 462
    },

In the end, I will need to group the result for Lineand LineStart, but I think I already have everything else (I get the date, counting hours, minutes, ... from the dates that I have).

, , - , .

db.collection.group()

, db.collection.group() , .

: MongoDB: , , , , , - .

Answer 1

, ,

db.Lines.aggregate([
{
    "$unwind": "$SSCEXPEND"
},
{
    "$unwind": "$SSCVALIDATIONS"
},
{
    "$match": {
        "$and": [
            {
                "SSCEXPEND.Title": 1
            },
            {
                "SSCVALIDATIONS.Result": {
                    "$gt": 10
                }
            }
        ]
    }
},
{
    "$group": {
        "_id": "$_id",
        "SSCEXPEND": {
            "$addToSet": "$SSCEXPEND"
        },
        "SSCVALIDATIONS": {
            "$addToSet": "$SSCVALIDATIONS"
        },
        "SSCCANCELATIONS": {
            "$first": "$SSCCANCELATIONS"
        }
    }
},
{
    "$project": {
        "SSCEXPENDCOUNT": {
            "$size": "$SSCEXPEND"
        },
        "SSCVALIDATIONSCOUNT": {
            "$size": "$SSCVALIDATIONS"
        },
        "SSCCANCELATIONSCOUNT": {
            "$size": "$SSCCANCELATIONS"
        }
    }
}
]).pretty()

Answer 2

. ,

db.c.aggregate([
{
    $project: {
         _id: 1,
         Line: 1,
         LineStart:1,

         SSCEXPEND: {
            $size: {
                $filter: {
                   input: "$SSCEXPEND",
                   as: "e",
                   cond:{ $eq: [ "$$e.Title", 1 ]}
                }
            }
         },
         SSCCANCELATIONS: {
            $size: "$SSCCANCELATIONS"
         },
         SSCVALIDATIONS:{
            $size: {
               $filter: {
                   input: "$SSCVALIDATIONS",
                   as: "v",
                   cond: {$lt: [ "$$v.Result", 10 ]}
                }
            }
         }

      }
}
])

$group, SSCEXPEND, SSCCANCELATIONS ..