Mongo 投影查询结果与 shell 与 nodejs 应用程序中的测试不同 [英] Mongo projection query results vary from testing in shell vs nodejs application

问题描述

我正在尝试从查询的文档中过滤字段

Hi I'm trying to filter fields from queried doc

这里是样本数据

db.inventory.insertMany( [
   {_id: 1, item: "journal", qty: 25, size: { h: 14, w: 21, uom: "cm" }, status: "A" },
   {_id: 2, item: "notebook", qty: 50, size: { h: 8.5, w: 11, uom: "in" }, status: "A" },
   {_id: 3, item: "paper", qty: 100, size: { h: 8.5, w: 11, uom: "in" }, status: "D" },
   {_id: 4, item: "planner", qty: 75, size: { h: 22.85, w: 30, uom: "cm" }, status: "D" },
   {_id: 5, item: "postcard", qty: 45, size: { h: 10, w: 15.25, uom: "cm" }, status: "A" }
]);

查询db.inventory.find({_id:1},{size:0}).pretty()

在抑制尺寸字段的文档下方返回

returns below doc suppressing the size feild

{ "_id" : 1, "item" : "journal", "qty" : 25, "status" : "A" }

在 node js 应用中实现相同的

implementing the same in node js application

db.collection("inventory").findOne({ _id: 1 }, { "size": 0 }, (err, result) => {
                    if (err) {
                        reject(err);
                    } else {
                        resolve(result);
                    }
                })

按原样返回文档而不抑制大小字段.

returns the doc as is without suppressing the size field.

{
    "_id": 1,
    "item": "journal",
    "qty": 25,
    "size": {
        "h": 14,
        "w": 21,
        "uom": "cm"
    },
    "status": "A"
}

如果我在这里遗漏了什么或做错了什么，请告诉我.我不想使用猫鼬.

Please let me know if I'm missing something here or doing it wrong. I don't want to use Mongoose.

推荐答案

findOne 函数在 node.js 驱动程序中的定义与 shell 中的函数略有不同.

The findOne function in the node.js driver has a slightly different definition than the one in the shell.

试试

db.collection("inventory").findOne({ _id: 1 }, {projection:{ "size": 0 }}, (err, result) => {

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