[Lesson] Count number of views per lesson

client/components/lessons/Lesson.tsx

@@ -1,4 +1,9 @@
-import React, { PropsWithChildren, useRef, useState } from 'react';
+import React, {
+  PropsWithChildren,
+  useEffect,
+  useRef,
+  useState,
+} from 'react';
 import Header from '~/components/Header';
 import Footer from '~/components/Footer';
 import { LessonMenu } from '~/components/lessons';
@@ -8,6 +13,7 @@ import { withSmoothScroll } from '~/services/Hooks';
 import { getLessonById, GITHUB_URL } from '~/services/Constants';
 import LessonExercises from './LessonExercises/LessonExercises';
 import { Chapter } from '../TableOfContents';
+import LessonService from '~/services/api/Lesson.service';
 
 interface Props {
   id: string;
@@ -33,7 +39,7 @@ export default function Lesson({
     articleWrapper.current.scrollTo(0, 0);
   };
 
-  const parseChapters = (chapters: {title: string; id: string}[]) => {
+  const parseChapters = (chapters: { title: string; id: string }[]) => {
     return chapters.map(parseOneChapter);
 
     function parseOneChapter(chapter: Chapter) {
@@ -47,6 +53,14 @@ export default function Lesson({
 
   const chaptersWithHref = parseChapters(chapters);
 
+  useEffect(() => {
+    LessonService
+      .increaseViews(id)
+      .catch((err) => {
+        console.error('[Lesson.tsx] got while trying to update view count', err);
+      });
+  }, []);
+
   return (
     <div className={styles.lesson}>
       <LessonMenu

client/services/api/Lesson.service.ts

@@ -0,0 +1,17 @@
+import HttpService from '../Http.service';
+
+class LessonService {
+  static get(lessonId: string) {
+    return HttpService
+      .get(`${process.env.ENDPOINT}/lessons/${lessonId}`)
+      .then((resp) => resp.json());
+  }
+
+  static increaseViews(lessonId: string) {
+    return HttpService
+      .post(`${process.env.ENDPOINT}/lessons/${lessonId}/views`)
+      .then((resp) => resp.json());
+  }
+}
+
+export default LessonService;

server/lesson/lesson.model.js

@@ -0,0 +1,59 @@
+const mongoose = require('mongoose');
+const { ServerError } = require('../ServerUtils');
+
+const LessonsSchema = new mongoose.Schema({
+  lessonId: { type: String, required: true, unique: true },
+  views: { type: Number, required: true },
+}, {
+  timestamps: {
+    updatedAt: 'updatedAt',
+  },
+});
+
+const Lesson = mongoose.models.Lesson || mongoose.model('Lesson', LessonsSchema);
+
+class LessonModel {
+  static get(lessonId) {
+    return Lesson.findOne({ lessonId });
+  }
+
+  static async updateViews(lessonId, views) {
+    let lesson = null;
+
+    try {
+      lesson = await LessonModel.get(lessonId);
+    } catch (err) {
+      console.error(`
+        [LessonModel.updateViews] got while fetching for lessonId=${lessonId}`,
+        err
+      );
+
+      throw err;
+    }
+
+    if (!lesson) {
+      lesson = new Lesson({ lessonId });
+      console.log(`[LessonModel.updateViews] created lesson on demand, with id=${lessonId}`);
+    }
+
+    lesson.views = views;
+
+    return new Promise((resolve, reject) => {
+      lesson.save((err) => {
+        if (err) {
+          console.error(`
+            [LessonModel.updateViews] got while saving lessonId=${lessonId}`,
+            err
+          );
+
+          reject(err);
+          return;
+        }
+
+        resolve();
+      });
+    });
+  }
+}
+
+module.exports = LessonModel;

server/lesson/lesson.router.js

@@ -0,0 +1,42 @@
+const express = require('express');
+const LessonModel = require('./lesson.model');
+const { ServerError } = require('../ServerUtils');
+
+const lessonRouter = express.Router();
+
+lessonRouter.get('/:lessonId', async function getLesson(req, res) {
+  const { lessonId } = req.params;
+  const lesson = await LessonModel.get(lessonId);
+
+  if (!lesson) {
+    new ServerError(404, `Lesson with id=${lessonId} doesn't exist!`).send(res);
+    return;
+  }
+
+  res.json(lesson);
+});
+
+lessonRouter.post('/:lessonId/views', async function increaseViews(req, res) {
+  const { lessonId } = req.params;
+
+  const lesson = await LessonModel.get(lessonId);
+
+  try {
+    if (!lesson) {
+      await LessonModel.updateViews(lessonId, 1);
+    } else {
+      await LessonModel.updateViews(lessonId, lesson.views + 1);
+    }
+
+    const updatedLesson = await LessonModel.get(lessonId);
+    res.json(updatedLesson);
+  } catch (err) {
+    new ServerError(
+      err.code || 500, 
+      err.message || 'Oops! A apărut o problemă. Încearcă din nou!'
+    );
+  }
+});
+
+
+module.exports = lessonRouter;

server/server.js

@@ -18,6 +18,7 @@ const demoRouter = require('./demo.router');
 const eventRouter = require('./event/event.router');
 const githubRouter = require('./github/github.router.js');
 const challengeRouter = require('./challenge/challenge.router.js');
+const lessonRouter = require('./lesson/lesson.router');
 
 const port = process.env.PORT || 3000;
 const app = express();
@@ -52,6 +53,7 @@ app.use('/api/demo', demoRouter);
 app.use('/api/events', eventRouter);
 app.use('/api/github', githubRouter);
 app.use('/api/challenges', challengeRouter);
+app.use('/api/lessons', lessonRouter);
 
 app.get('*', (req, res) => {
   nextHandler(req, res, req.url);