How to append in an array mongoDB

Question

How can i append something in an array after i search a specific object, Database looks like this:

{
    "_id": {
        "$oid": "608a0f3628588a3daca019c6"
    },
    "username": "paul",
    "password": "cacavaca",
    "question": "q1",
    "answer": "cutu",
    "friends": [mir],
    "groups": []
}
{
    "_id": {
        "$oid": "608a0f4328588a3daca019c7"
    },
    "username": "mir",
    "password": "123456",
    "question": "q1",
    "answer": "cutu",
    "friends": [],
    "groups": []
}

I want to search the object by username: paul and append alex in the friends array, i have tried this but its not wokring:

MongoClient.connect(uri, function(err, db) {
        var dbc = db.db("chat");
        dbc.collection("accounts").find({username: { $eq: user}}).update( [
            {
              $push: {
                friends:alex
              }
            }

        ])
        db.close();
    });

Jérôme · Accepted Answer · 2021-04-29 12:44:16Z

1

I think instead of use .find() method, you should use updateOne() like this :

MongoClient.connect(uri, function(err, db) {
    var dbc = db.db("chat");
    dbc.collection("accounts").updateOne({username: {$eq: user}}, {
       $push: {
           friends: alex
        }
    });
    db.close();
});

Supposing user and alex are variables defined above.

Also, maybe you can only write {username: user} without $eq but it depends your code and logic.

answered Apr 29, 2021 at 12:44

Jérôme

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Comments

Paul Taran · Accepted Answer · 2021-04-29 12:43:08Z

0

This is the correct way:

var user = request.body.user;
var new_friend = request.body.new_friend;

MongoClient.connect(uri, function(err, db) {
        var dbc = db.db("chat");
        dbc.collection("accounts").update(
        {username: { $eq: user}},
            {
              $push: {
                friends:new_friend
              }
            }
        )
        db.close();
    });

answered Apr 29, 2021 at 12:43

Paul Taran

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