mongoDB-如何在多个文档中查找和排序多个字段并将它们存储在单个数组中？

Question

The header describes the problem well I think. I have a collection named "results" with serveral documents:

{
    "_id" : "item_e4a2086048057ac9",
    "home" : "FH>87218379012",
    "username:" : "Jon Doe",
    "Apps" : {
        "game" : {
            "InVals" : {
                "ET" : {
                    "et1" : 1,
                    "et2" : 88,
                    "et3" : 7,
                    "et4" : 0.68,
                    "et5" : 5253,
                    "et6" : "7233-AL",
                    "et7" : "23-PL",
                    "et8" : "791-GY"
                }
            },
            "OutVals" : {
                "ET" : 74.00
            }
        }
    },
    "PAT" : 74
}

Second document:

{
    "_id" : "item_a90a2086048057ac9",
    "home" : "FH>87218379012",
    "username:" : "Jon Doe2",
    "Apps" : {
        "game" : {
            "InVals" : {
                "ET" : {
                    "et1" : 0,
                    "et2" : 9,
                    "et3" : 96,
                    "et4" : 3218,
                    "et5" : 6,
                    "et6" : "65-AL",
                    "et7" : "265-PL",
                    "et8" : "4-GY"
                }
            },
            "OutVals" : {
                "ET" : 4.00
            }
        }
    },
    "PAT" : 4
}

And so on... Now I need to query all "PAT"-fields in the specific documents, where the field "home" is equal to "FH>87218379012", than sort them in descending order and store them in a variable which is an array:

var resultsArray = [74, 4....,n];

It would also be ok if there is an solution, where I have to store each "PAT"-Value in a single variable, sort them and save them in an array later. At the end I just need to have all "PAT" values of the documents which have "FH>87218379012" as "home" in descended order in an array.

Is that possible or do I have to change something in my collection?

Answer 1

You can use an aggregation to match your PAT value, sort by that field and add a $group stage to $push the values to an array :

db.coll.aggregate([{
    $match: {
        home: "FH>87218379012"
    }
}, {
    $sort: { PAT: -1 }
}, {
    $group: {
        _id: null,
        result: {
            $push: "$PAT"
        }
    }
}])