demo_10_01 云数据库聚合_addFields

数据表:
{
    "scores": { // 集合(表名)
        "data": [ // 数据
            {
                "_id": 1,
                "student": "Maya",
                "homework": [10, 5, 10],
                "quiz": [10, 8],
                "extraCredit": 0
            },
            {
                "_id": 2,
                "student": "Ryan",
                "homework": [5, 6, 5],
                "quiz": [8, 8],
                "extraCredit": 8
            }
        ]
    }
}
 
聚合操作:
‘use strict‘;
const db = uniCloud.database();
const $ = db.command.aggregate;
exports.main = async(event, context) => {
    const msg = db.collection(‘scores‘).aggregate()
        // 添加两个字段:
        .addFields({
            totalHomework: $.sum(‘$homework‘),
            totalQuiz: $.sum(‘$quiz‘)
        })
        // 根据上面新添加的两个字段值在添加一个字段
        .addFields({
            totalScore: $.add([‘$totalHomework‘, ‘$totalQuiz‘, ‘$extraCredit‘])
        })
        .end();
    return msg;
};

// 聚合之后的返回值
/*

{
    "affectedDocs": 2,
    "data": [{
        "_id": 1,
        "extraCredit": 0,
        "homework": [10, 5, 10],
        "quiz": [10, 8],
        "student": "Maya",
        "totalHomework": 25,
        "totalQuiz": 18,
        "totalScore": 43
    }, {
        "_id": 2,
        "extraCredit": 8,
        "homework": [5, 6, 5],
        "quiz": [8, 8],
        "student": "Ryan",
        "totalHomework": 16,
        "totalQuiz": 16,
        "totalScore": 40
    }]
}

*/

demo_10_01 云数据库聚合_addFields

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