Is there a way to retrieve MongoDB count results in Node.js using a callback function?

Is there a way to access mongodb count results in nodejs so that the outcome can be easily retrieved by asynchronous requests? Currently, I am able to retrieve the result and update the database successfully. However, when it comes to accessing the variables in the asynchronous request, they either appear empty or are not accessible. It seems like the variables are being updated with the values from the previous request instead of waiting for the current query to finish. How can I structure this code properly so that the variables are populated within the callback function? Any advice would be greatly appreciated!

testOne.increment = function(request) {   
    var MongoClient = require('mongodb').MongoClient,
        format = require('util').format;
    MongoClient.connect('mongodb://127.0.0.1:27017/bbb_tracking', function(err, db) {
    if (err) throw err;
    collection = db.collection('bbb_tio');
        collection.count({vio_domain:dom}, function(err, docs) {
    if (err) throw err;                                     
    if (docs > 0) {
            var vio_val = 3;                                        
        } else {
            var vio_val = 0;                    
        }                   
        if (vio_val === 3) {
                event = "New_Event";
        var inf = 3;
            }                                       
        db.close();

        console.log("docs " + docs);
        });       
   });                    
};

Answer №1

To ensure proper handling of the asynchronous nature of the count function, it is important to pass a callback to the increment function. This allows for the execution of the callback when the count value is retrieved from the database.

testOne.increment = function(request, callback) {   
    var MongoClient = require('mongodb').MongoClient,
        format = require('util').format;
    MongoClient.connect('mongodb://127.0.0.1:27017/bbb_tracking', function(err, db) {
        if (err) throw err;
        var collection = db.collection('bbb_tio');
        // It's unclear where the dom value originates.
        collection.count({vio_domain:dom}, function(err, count) {
            var vio_val = 0;
            if (err) throw err;                                     
            if (count > 0) {
                vio_val = 3;                                        
                event = "New_Event";
                var inf = 3;
            }                                       
            db.close();

            console.log("docs count: " + count);        
           // Invoke the callback here with appropriate parameters
           callback(null, count);   
        });       
   });                 
};

testOne.increment({}, function(err, count) {
   // The count value can be accessed and utilized here...
});

(I have made some adjustments to clarify the code structure by avoiding unnecessary redeclarations of variables within conditional blocks).

Answer №2

If you're looking to streamline your code and make it easier to troubleshoot, consider using the 'async' module. Check out the code examples for adduser.js and deleteuser.js on GitHub referenced in this post:

Best regards, Ganesh

Answer №3

Length provides the number of results in the array

const filteredUsers = await User.find({ role: roleName, 'name': new RegExp(searchTerm, 'i')  },{date: 0,__v:0,password:0}).
      sort(sortingObject)
      .limit(limitNumber)
      .skip(skipValue);
console.log(filteredUsers.length);

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