javascript - 将 MongoDB 查询结果转换为 JSONArray

Question

我通过 mongoose 进行了 MongoDB 查询，结果是:

[
  {
    "tablename": "name1"
  },
  {
    "tablename": "name2"
  }
]

但我需要它作为 JSONArray :

{
  "tablename": [
    "name1",
    "name2"
  ]
}

有没有简单的转换方法？

Answer 1

aggregation framework 可以为您创造想要的结果。考虑$group 和 $push 累加器运算符如下:

db.collection.aggregate([
    {
        "$group": {
            "_id": null,
            "tablename": {
                "$push": "$tablename"
            }           
        }
    },
    {
        "$project": {
            "_id": 0, "tablename": 1
        }
    }    
])

示例输出:

/* 0 */
{
    "result" : [ 
        {
            "tablename" : [ 
                "name1", 
                "name2"
            ]
        }
    ],
    "ok" : 1
}

您可以使用 aggregate() 在 mongoose 中实现此功能方法，例如:

var pipeline = [
        {
            "$group": {
                "_id": null,
                "tablename": {
                    "$push": "$tablename"
                }           
            }
        },
        {
            "$project": {
                "_id": 0, "tablename": 1
            }
        }    
    ]

Model.aggregate(pipeline).exec(function (err, res){
    console.log(res);
})

<小时/>

更新

更改此查询以使用聚合框架:

app.post('/getkost', function(request, response){ 
    var kost = new RegExp(request.body.kost,'i'); 
    Move.find(
        { tablename: { $regex: kost } },
        { tablename: 1, _id: 0 }, 
        function(err, doc) { 
            response.json(doc); 
    }); 
});

对此:

app.post('/getkost', function(request, response){ 
    var kost = new RegExp(request.body.kost, 'i'); 
    var pipeline = [
        {
            "$match": {
                "tablename": { "$regex": kost }
            }
        },
        {
            "$group": {
                "_id": null,
                "tablename": {
                    "$push": "$tablename"
                }           
            }
        },
        {
            "$project": {
                "_id": 0, "tablename": 1
            }
        }
    ]
    Move.aggregate(pipeline, function(err, res) { 
        response.json(res); 
    }); 
});