perf: pagination, filter and sort on backend

pages/api/product/category/[categoryName].js

-const Product = require('../../../../models/product');
-import dbConnect from '../../../../utils/helpers/dbHelpers';
+const Product = require('../../../models/product');
+import dbConnect from '../../../utils/helpers/dbHelpers';
 
 async function handler(req, res) {
   const { method } = req;
-  const categoryName = req.query.categoryName;
+
   await dbConnect();
 
+  const pageIndex = req.query.pageIndex;
+  const category = req.query.category === 'All' ? '' : req.query.category;
+  const filterType = req.query.filterType;
+
+  if (pageIndex < 1) {
+    res.status(422).json({
+      message: 'Page does not exist ',
+    });
+    return;
+  }
+
   switch (method) {
     case 'GET': {
       try {
-        const productsByCategory = await Product.find({
-          category: categoryName,
-        });
+        const productCount = await Product.find({
+          category: { $regex: category },
+        }).countDocuments();
 
-        if (!productsByCategory) {
+        if (productCount === 0) {
           res.status(200).json({
-            message:
-              'There are currently no products in our database for the selected category.',
-            productsByCategory: [],
+            message: 'There are currently no products in our database.',
+            product: [],
+            productCount: 0,
+            next: null,
+            previous: null,
           });
+          break;
+        }
+
+        if ((pageIndex - 1) * 9 >= productCount) {
+          throw new Error('Page does not exist!');
+        }
+
+        const product = await Product.find({ category: { $regex: category } })
+          .skip((pageIndex - 1) * 9)
+          .limit(9)
+          .sort(filterType === 'asc' ? 'name' : '-name ');
+
+        if (!product) {
+          throw new Error('There are currently no products in our database.');
         }
 
+        const previousUrl =
+          pageIndex > 1
+            ? `https://localhost:3000/api/product?pageIndex=${
+                parseInt(pageIndex) - 1
+              }`
+            : null;
+        const nextUrl =
+          pageIndex * 9 < productCount
+            ? `https://localhost:3000/api/product?pageIndex=${
+                parseInt(pageIndex) + 1
+              }`
+            : null;
+
         res.status(200).json({
-          message:
-            'All products from our database for the selected category were fetched successfully.',
-          productsByCategory,
+          message: 'All products from our database were fetched successfully.',
+          product,
+          productCount,
+          next: nextUrl,
+          previous: previousUrl,
         });
       } catch (error) {
         res.status(400).json({ message: error.message });
       }
       break;
     }
+    case 'POST': {
+      try {
+        const product = await Product.create(req.body);
+        res
+          .status(201)
+          .json({ message: 'Your product was created and stored!', product });
+      } catch (error) {
+        res.status(400).json({ success: false });
+      }
+      break;
+    }
     default:
       res.status(405).json({ message: 'Method not allowed' });
       break;

requests/products/productRequest.js

-import apiEndpoints from '../apiEndpoints';
-
-export const getAllProducts = async (pageIndex) => {
+export const getAllProducts = async ({
+  url,
+  category = 'All',
+  filter = 'asc',
+}) => {
   const response = await fetch(
-    `http://localhost:3000${apiEndpoints.products}?page=${pageIndex}`
+    `${url}&category=${category}&filterType=${filter}`
   );
 
   const data = await response.json();