How to accurately use foreach in nodejs for Mongodb operations

Question

This is my code to get data from the groupname group, which is initialized with the name of the collection. I want to iterate over data stored in a doc using a loop foreach.

var db = mongojs('login');

    var cursor = db.collection(groupname).find();
    console.log(cursor);

    cursor.each(function(err, doc) {
        console.log(doc._id);

        mongo.collection(doc._id + "group", function(err, collection) {
            collection.remove({"groupname": groupname});
        });
    });

I tried to do it db.collectionname.find().forEach(....), but I have an error saying that such a function does not exist. Please, help.

Answer 1

The call find()to retrieve records from Mongo DB is asynchronous. You are trying to use documents before the data is available. You must have a loop forEachin the callback find().

`

db.collection(groupname).find({}, function(err, doc){
console.log(doc);
doc.forEach(function(err,doc){
    console.log(doc._id);
    db=mongo.collection(doc_id+"group");
    db.remove({"groupname":groupname});
});
});

`

Answer 2

each(), find():

// Grab a cursor
var cursor = db.collection(groupname).find();
console.log(cursor);

// Execute the each command, triggers for each document
cursor.each(function(err, doc) {
    console.log(doc._id);
    // Fetch a collection to remove document
    mongo.collection(doc._id + "group", function(err, collection) {
        collection.remove({"groupname": groupname});
    }
});

- -

, mongojs, , Node.js , , :

// connect now, and worry about collections later
var db = mongojs('login')
var groupcollection = db.collection(groupname)

groupcollection.find({}, function(err, groups) {
    if( err || !groups) console.log("No groups found");
    else groups.forEach( function(group) {
        console.log(group);
        mongo.collection(group._id + "group", function(err, collection) {
            collection.remove({"groupname": groupname});
        });
    });
});