How can I read data from MongoDB through pure NodeJS?

Question

I am trying to save and read some data from MongoDB using standard MongoClient and pure NodeJS. The fact is that I can write data, but not read . Here is my code.

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/test";
var db;

MongoClient.connect(url, function (err, database) {
    if (err !== null) {
        throw err;
    }
    db = database;
});

Reading function

function selectDB(tableName, key, value, callback) {
    var req = {};
    req[key] = value;
    db.collection(tableName).find(req, callback);
}

Recording function

function insertDB(tableName, obj) {
    db.collection(tableName).insertOne(obj, function (err, res) {
        if (err !== null) {
            throw err;
        } else {
            console.log(res);
        }
    });
}

After I inserted the data into db using this, it can be found using the Mongo shell. I use the bash find()function in the shell successfully, but not in the js code.

Update

Now I pass the callback to the function toArray()as indicated here, but I still don't get the result: the callback is not being executed. My function selectDB()now looks like this.

var req = {};
req[key] = value;
db.collection(tableName).find(req).toArray(callback);

Update

Here is a sample data example: Shell Input:

> db.users.find({"email":"aa@aa"})

Conclusion:

{ "_id" : ObjectId("572ba1a599f59780f549e5e3"), "email" : "aa@aa", "password" : "2GU9I8syq2Oyf6rSqJNDVyFPOTRwPg3nyQjSwPXppvM=" }

Js

( req):

key = "email" value = "aa@aa"

, .

, (callback):

//select() here is an alias for selectDB() function declared earlyer
db.select("users", "email", user.email, function (err, cursor) {
        if (cursor === undefined || cursor == null || err !== null) {
            error();
        } else if (cursor.password === user.password) {
            success();
        } else {
            wrong();
        }
    });

, . error() , undefined.

- , , , .

Answer 1

node -mongodb-native (driver) ? find .