Get total count along with Mongoose Query skip & limt

You can use async library for running 2 queries at once. In your case you can run one query to get the number of documents and another for pagination.

Example with 'User' model:

    var async = require('async');    var User = require('./models/user');    var countQuery = function(callback){         User.count({}, function(err, count){               if(err){ callback(err, null) }               else{                   callback(null, count);                }         }    };    var retrieveQuery = function(callback){        User.find({}).skip((page-1)*PAGE_LIMIT)                     .limit(PAGE_LIMIT)                     .exec(function(err, doc){                            if(err){ callback(err, null) }                            else{                            callback(null, doc);                            }                      }    };    async.parallel([countQuery, retrieveQuery], function(err, results){         //err contains the array of error of all the functions         //results contains an array of all the results         //results[0] will contain value of doc.length from countQuery function         //results[1] will contain doc of retrieveQuery function         //You can send the results as         res.json({users: results[1], pageLimit: PAGE_LIMIT, page: page, totalCount: results[0]});    });

async allows you to run a number of queries in parallel depending on the hardware you are using. This would be faster than using 2 independent queries to get count and get the required documents.Hope this helps.

I have solved it with $facet and aggregate the following way in mongoose v3+:

const [{ paginatedResult, [{ totalCount }] }] = await Model.aggregate([{  $facet: {    paginatedResult: [      { $match: query },      { $skip: skip },      { $limit: limit }    ],    totalCount: [      { $match: query },      { $count: 'totalCount' }    ]  }}])

where the totalCount refers the total number of records matching the search query while the paginatedResult is only the paginated slice of them.

The problem with these solutions is that for every request you are doing two queries. This becomes problematic when you have a complex data structure and large data set as performance becomes an issue. Consider instead creating a special function that listens for the /resource?count=true or /resource/count GET methods and returns only the count.