CODEWITHSUNDEEP
node.jsmongodbexpressmongoose
joselegit
joselegit

Reputation: 533

Mongoose pagination from server side

I am trying to add server side pagination to a NodeJS, Express and MongoDB API. The API use mongoose to handle the database. I am lost in how to customize the response from the Controller.

Model:

const mongoose = require('mongoose');
const Schema =  mongoose.Schema;

const clientSchema = Schema({
  code: {
    type: String,
    required: [true,'Code no puede estar vacio']
  },
  name: {
    type: String,
    required: [true,'Name no puede estar vacio']
  }
},{
  timestamps: true
});

const Client = module.exports = mongoose.model('clients',clientSchema);

Controller for get all clients:

const mongoose = require("mongoose");
const Client = require('../models/client');
const clientController = {};


clientController.index = (limit, callback) => {
  Client.find(callback).limit(limit);
};

module.exports = clientController;

Route to get the clients:

  app.get('/api/clients', (req, res) => {
      Client.index(limit,(err, client) => {

        if (err) {
          res.status(500).json({
            msg: "Error en aplicacion",
            err
          });
        }
        res.status(200).json(client);
      });
  });

How can I customize the result in the controller to something like this:

[
{
"totalRecords":"99999999999",
"offset":"888888",
"page":"4",
"nextPage":"5"
"result":{...}
}
]

I already have a function to calculate the pagination, But I don't know how to add the information about the pagination in the result of the controller.

Before I was adding the pagination data in the route, But I want to handle the pagination logic in the controller.

Or is better handle the pagination in the route?

Thanks in advance

Upvotes: 5

Views: 9719

Answers (1)

Mihir Bhende
Mihir Bhende

Reputation: 9045

You can create a method in mongoose model called as paginate :

Add this before declaring mongoose model :

clientSchema.methods.paginate = function(pageNo, callback){

    var limit = 10;
    var skip = pageNo * (limit - 1);
    var totalCount;
    
    //count documents
    this.count({}, function(err, count)){
        if(err){
            totalCount = 0;
        }
        else{
            totalCount = count;
        }
    }
    if(totalCount == 0){
        return callback('No Document in Database..', null);
    }
    //get paginated documents
    this.find().skip(skip).limit(limit).exec(function(err, docs){

        if(err){
            return callback('Error Occured', null);
        }
        else if(!docs){
            return callback('Docs Not Found', null);
        }
        else{
            var result = {
                "totalRecords" : totalCount,
                "page": pageNo,
                "nextPage": pageNo + 1,
                "result": docs
            };
            return callback(null, result);
        }

    });

});

const Client = module.exports = mongoose.model('clients',clientSchema);

Then in controller change :

app.get('/api/clients', (req, res) => {
    //You could put page number in request query ro request params
    Client.paginate(req.body.pageNo, function(err, response) {
        if (err) {
            return res.status(500).json({
                message : "Error en aplicacion",
                error : err
            });
        }
        return res.status(200).json(response);
    });
});

Upvotes: 6

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