投影无法在mongo中与db.collection.find一起使用 [英] projection not working with db.collection.find in mongo

问题描述

一天前，我已经开始使用mongodb，并且遇到了问题. 我在net和stackoverflow上搜索了如何在最终答案中隐藏_id值，并按照提供的答案进行了尝试，使我的代码得以运行，但_id部分仍然显示.

I have started to use mongodb just a day back and have encountered an issue. I searched on net and stackoverflow for how to hide _id value in final answer and following the answers provided I tried to get my code run but still the _id part shows.

P.S .:我正在使用cloud9作为想法.

P.S.: I am using cloud9 as the ide.

var mongo = require('mongodb').MongoClient;
mongo.connect('mongodb://localhost:27017/learnyoumongo', function(err, database) {
        if(err) throw err;
        const db = database.db('learnyoumongo');
        var parrots = db.collection('parrots');
        parrots.find({
            age: { $gt: +process.argv[2] }
        },{
            name: 1,
            age: 1,
            _id: 0
        }).toArray(function(err, docs){
            if(err) throw err;
            console.log(docs);
            database.close();
        });
});

推荐答案

您可以这样分离投影:

    parrots.find({
        age: { $gt: +process.argv[2] }
    }).project({_id:0}).toArray(function(err, docs){
        if(err) throw err;
        console.log(docs);
        database.close();
    });

我遇到无法投影的问题，上述方法对我有效

i had the same issue with being unable to get projection to work, and the above method worked for me

这篇关于投影无法在mongo中与db.collection.find一起使用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！