Nodejs MongoDB Pagination - Backend Server Side Pagination

Author: loizenai

Angular-10-Nodejs-MongoDB-Pagination/app/config/mongodb.config.js

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+module.exports = {
+  url: 'mongodb+srv://loizenai:loizenai@cluster0.gmd7e.mongodb.net/loizenaidb?retryWrites=true&w=majority'
+}

Angular-10-Nodejs-MongoDB-Pagination/app/controllers/customer.controller.js

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+const Customer = require('../models/customer.model.js');
+ 
+// POST a Customer
+exports.create = (req, res) => {
+
+    const customer = new Customer({
+                          firstname: req.body.firstname,
+                          lastname: req.body.lastname,
+                          age: req.body.age,
+                          salary: req.body.salary,
+                          address: req.body.address,
+                        });
+ 
+    // Save a Customer in the MongoDB
+    customer.save().then(data => {
+                    // send uploading message to client
+                    res.status(200).json({
+                      message: "Upload Successfully a Customer to MongoDB with id = " + data.id,
+                      customer: data,
+                    });
+                }).catch(err => {
+                    res.status(500).json({
+                      message: "Fail!",
+                      error: err.message
+                    });
+                });
+};
+
+exports.getSalaries = (req, res) => {
+  try {
+    Customer.find({}).distinct("salary")
+                .then(result => {
+                  let salaries = result.sort(function(a, b){return b - a});
+                  res.send(salaries);
+                });
+  } catch (error) {
+    res.status(500).send({
+      message: "Error -> Can NOT get all customer's salaries",
+      error: error.message
+    });
+  }
+}
+
+exports.paginationfilterandsort = async (req, res) => {
+  try {
+    let page = parseInt(req.query.page);
+    let limit = parseInt(req.query.size);
+    let agesorting = (req.query.agesorting === 'true');
+    let desc = (req.query.desc === 'true');
+    let salary = req.query.salary ? parseInt(req.query.salary) : -1;
+  
+    const offset = page ? page * limit : 0;
+
+    console.log("offset = " + offset);    
+
+    let result = {};
+    let numOfCustomer;
+    
+    // NOT Filtering with salary
+    if(salary < 0){
+      numOfCustomer = await Customer.countDocuments({});
+      // not sorting with age
+      if(agesorting == false) {
+        result = await Customer.find({})  // You may want to add a query
+                        .skip(offset) // Always apply 'skip' before 'limit'
+                        .limit(limit)
+                        .select("-__v"); // This is your 'page size'
+      } else {
+        if(desc == false) { // sorting with age and ascending
+          result = await Customer.find({})  // You may want to add a query
+                            .skip(offset) // Always apply 'skip' before 'limit'
+                            .limit(limit)
+                            .sort({"age": 1})
+                            .select("-__v"); // This is your 'page size'
+        } else { // sorting with age and descending
+            result = await Customer.find({})  // You may want to add a query
+                              .skip(offset) // Always apply 'skip' before 'limit'
+                              .limit(limit)
+                              .sort({"age": -1})
+                              .select("-__v"); // This is your 'page size'
+        }
+      }
+    } else { // Filtering with salary
+
+      numOfCustomer = await Customer.countDocuments({salary: salary});
+      // not sorting with age
+      if(agesorting == false) {
+        if(desc == false) { // sorting with age and ascending
+          result = await Customer.find({salary: salary})  // You may want to add a query
+                            .skip(offset) // Always apply 'skip' before 'limit'
+                            .limit(limit)
+                            .select("-__v"); // This is your 'page size'
+        }
+      } else {
+        if(desc == false) { // sorting with age and ascending
+          result = await Customer.find({salary: salary})  // You may want to add a query
+                            .skip(offset) // Always apply 'skip' before 'limit'
+                            .limit(limit)
+                            .sort({"age": 1})
+                            .select("-__v"); // This is your 'page size'
+        } else { // sorting with age and descending
+          result = await Customer.find({salary: salary})  // You may want to add a query
+                            .skip(offset) // Always apply 'skip' before 'limit'
+                            .limit(limit)
+                            .sort({"age": -1})
+                            .select("-__v"); // This is your 'page size'
+        }
+      }
+    }
+
+    const response = {
+      "copyrightby": "https://loizenai.com",
+      "totalItems": numOfCustomer,
+      "totalPages": Math.ceil(numOfCustomer / limit),
+      "pageNumber": page,
+      "pageSize": result.length,
+      "customers": result
+    };
+
+    res.status(200).json(response);
+  } catch (error) {
+    res.status(500).send({
+      message: "Error -> Can NOT complete a paging request!",
+      error: error.message,
+    });
+  }
+};

Angular-10-Nodejs-MongoDB-Pagination/app/models/customer.model.js

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+const mongoose = require('mongoose');
+ 
+const CustomerSchema = mongoose.Schema({
+    firstname: String,
+    lastname: String,
+    address: String,
+    salary: { 
+      type: Number, 
+      required: true 
+    },
+    age: { 
+      type: Number, 
+      min: 18, 
+      max: 65, 
+      required: true 
+    },
+    copyrightby: {
+      type: String,
+      default: 'https://loizenai.com'
+    }
+});
+
+CustomerSchema.virtual('id').get(function(){
+  return this._id.toHexString();
+});
+
+// Ensure virtual fields are serialised.
+CustomerSchema.set('toJSON', {
+  virtuals: true
+});
+
+module.exports = mongoose.model('Customer', CustomerSchema);

Angular-10-Nodejs-MongoDB-Pagination/app/routes/customer.router.js

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+module.exports = function(app) {
+ 
+  var customers = require('../controllers/customer.controller.js');
+
+  // Create a new Customer
+  app.post('/api/customers/create', customers.create);
+  app.get('/api/customers/salaries', customers.getSalaries);
+  app.get('/api/customers/pagefiltersort', customers.paginationfilterandsort);
+}