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Build a Quiz app with Angular and Webiny Headless CMS

Mandah IsraelTwitter
November 23, 2022

Building an application to host quizzes is a popular coding challenge. Often, though, the questions and answers are hard-coded into the application itself. But what if you needed to update them? In this tutorial, we will store questions and answers in Webiny Headless CMS and render a quiz UI using Angular.

Prerequisites

To follow along, you need to have the following:

  • Basic knowledge of Angular and GraphQL.
  • Angular CLI installed.
  • AWS account with credentials set up on your system.
  • Node.js >=14 and yarn ^1.22.0 || >=2 installed in your system.

Introduction to Webiny

Webiny is an open-source serverless CMS that offers enterprise-grade functionalities while allowing us to define our own security parameters based on our requirements. Being serverless, the infrastructure has been abstracted away allowing engineers to focus on deliverables.

Webiny includes several features, among which is its GraphQL-based Headless CMS for storing and managing content, which can then be accessed via its content delivery API using our native tools.

In this tutorial, to build a Quiz app we will be using the Webiny Headless CMS.

Setting Up Our Webiny Headless CMS

To get started, we need to first create a Webiny project, deploy it and then model our content in the headless CMS using the generated Admin app.

To create a new Webiny project, enter the following command in the terminal:

npx create-webiny-project webiny-quiz

After running, when prompted to choose a database, select DynamoDB which is suitable for our use case. Once the new project has been created, we can then cd into it and deploy it with the following commands.

cd webiny-quiz yarn webiny deploy

After deployment is done a URL to the Admin app, GraphQL API endpoints, and React website will be printed out in the terminal which we will use shortly.

We can find the API endpoints at any time by running yarn webiny info --env=dev from the Webiny folder in the terminal.

If we don’t want to do the installation ourselves, we can get a fully featured demo by filling out this form: http://webiny.typeform.com/to/VYffkZlR.

Defining Content Model in the Admin App

Here we will define the structure of the content we want to store in the CMS which can be done in the generated Admin app. For our use case, we will have a Quiz and Question model. As their name implies Quiz will hold the quizzes like CSS quiz, React quiz, etc, while Question will hold the questions as well as the options and answers for all quizzes.

Now open the Admin app by clicking on its URL which was printed in the terminal earlier when we deployed our project. If it's the first time accessing the Admin app, we will be prompted to create a default user with our details. After doing so, we will be taken to the welcome page:

image.png

Now to create our models, navigate to the Content Models page by clicking on NEW CONTENT MODEL under Headless CMS, and on the next page click on New Modal at the top of the page and we will see a prompt with a form to add some information for a new Content Model. which looks like this:

image (1).png

For the Quiz model, enter Quiz in the name field then click on the CREATE MODEL button. Once the model has been created we will be taken to a page where we can add its fields. we will be doing that shortly. For now, navigate back to the Content Models page, and let’s create a Question model following the same process as was done with the Quiz model.

Each model has a page where we can add different field types by dragging and dropping the needed fields in the drop zone which looks like the following:

image (2).png

After creating a model we will be taken to this page. You can navigate to it by clicking on thweree edit icon of a model on the Content Models page.

Let’s create the field for our models. For the Quiz model, create the following fields:

  • TEXT field with label: name.
  • LONG TEXT field with label: description.

image (3).png

Then click on the SAVE button at the top right of the page. For the Question model:

  • Six TEXT fields with labels: title, option1, option2, option3, option4, and answer.
  • REFERENCE field with label ref and Content Models Quiz.

image.png

Then click on Save.

Adding Content

Now that we have defined our models let’s start adding content to them. To add quizzes, in the sidebar, expand the Headless CMS tab, under the UNGROUPED section click on Quizzes and we will see the following page:

image (1).png

Next, click on the NEW ENTRY button, and on the prompt that appears, enter the name and description of the quiz, then click on SAVE & PUBLISH at the top right of the page.

image.png

Here we can add as many quizzes as we want. Next, let’s add the questions. On the sidebar, click on Questions, then in the next page click on NEW ENTRY and add the title, options to choose from for answering the question, the answer to the question, and a reference to a quiz the question is for.

image (1).png

After that, click on SAVE & PUBLISH. Make sure to add more than one question for a quiz. It's important for the rest of the tutorial.

Setting Up the Frontend Application

Here, we will start by creating a new angular app and building the UI for the Quiz app. Then later on we will integrate Webiny into it adding the functionalities.

The quiz app will contain a quizzes page that shows a list of quizzes created in our CMS, a quiz page that will display the questions for a quiz in a paginated pattern, and a score page that will display the total score from the answered questions in a quiz. Here are images showing what we will be building:

image (2).png

image (3).png

image (4).png

Initiating an Angular app

To generate a new angular app, enter the following commands in the terminal:

ng new quiz-app

When prompted, pick CSS for styling and add router to the app. The above will create a starter angular app called quiz-app. Next, let’s install Apollo Client) to work will GraphQL in our app. Enter the following command:

ng add apollo-angular

When prompted to add a URL, leave it blank. We will set that up later. Since we are using the ng-add command, all the required packages will be installed and the module for initializing Apollo client will be created in the app folder named graphql-module.ts.

Now let’s clean up the app a little, removing codes that are not needed. Open the created app in a code editor and first modify src/app/app.component.html to the following:

<div></div>

Next, add the following styling to src/styles.css:

body { background-color: rgb(248,249,250); min-width: 100vh; font-family: system-ui; } * { margin: 0; padding: 0; } .container { width: 90%; margin: 0 auto; }

Now, let’s start the development server with the ng serve command.

Building the interfaces with Angular

Let’s start by creating the pages and components we will be using and setting up the routes. For pages, in the terminal, make sure you are in the root directory of the app and enter the following commands:

# For Bash for page in quizzes quiz score; do ng g c --module app "pages/${page}"; done # For Windows for %n in (quizzes, quiz, score) do ng g c --module app pages/%n

And for the components, enter the following commands in the terminal:

# For Bash for comp in quizCard question; do ng g c --module app "components/${comp}"; done # For Windows for %n in (quizCard, question) do ng g c --module app components/%n

After entering the above commands, here is what the folders in src/app will look like:

app ┣ components ┃ ┣ question ┃ ┗ quiz-card ┣ pages ┃ ┣ quiz ┃ ┣ quizzes ┃ ┗ score

Now, let’s define the routes. In src/app/app-routing.module.ts add the following imports and modify the routes variable:

import { QuizComponent } from './pages/quiz/quiz.component'; import { QuizzesComponent } from './pages/quizzes/quizzes.component'; import { ScoreComponent } from './pages/score/score.component'; const routes: Routes = [ {path: '', component: QuizzesComponent}, {path: 'quiz/:id', component: QuizComponent}, {path: 'score', component: ScoreComponent} ];

Next, modify src/app/app.component.html to the following:

<div> <router-outlet></router-outlet> </div>

Now, let’s build the interface. For now, in the interface, we will be using mock data in order to add the right styling, but later on, we will fetch and display the one from our CMS.

We will start with the quizzes page. On the quizzes page, each quiz will be displayed in the form of a card which will be a component on its own. Let’s create the UI for that component.

Head over to the app/components/quiz-card/quiz-card.component.ts file and add the following import:

import { Input } from '@angular/core';

Next, let’s add the properties we will use later on in this tutorial. Add the following lines of code before the constructor in the QuizCardComponent class:

@Input() quizData: any; questionsLength = 0

Next, modify its HTML file quiz-card.component.html file to the following:

<div class="quizCard"> <h3>CSS Quiz</h3> <p>A simple quiz to test your knowledge of CSS</p> <span>questions: <span>{{questionsLength}}</span></span> <button [routerLink]="['quiz', 1]">Take quiz</button> </div>

Then add the following styling to quiz-card.component.css:

.quizCard { background-color: white; padding: 15px; border-radius: 5px; border: 1px solid gainsboro; text-align: left; max-width: 250px; display: flex; justify-content: space-between; flex-direction: column; } .quizCard h3 { font-weight: 400; } .quizCard p { color: rgb(73,80,87); } .quizCard > span { display: block; margin-top: 10px; font-size: 14px; margin-bottom: 20px; color: rgb(73,80,87); } .quizCard span span { color: black; } .quizCard button { padding: 5px 10px; background-color: coral; border-radius: inherit; border: none; color: white; width: fit-content; } .quizCard button:hover { background-color: rgb(254, 111, 59); }

Now, let’s render the quizCard component on the quizzes page. Head over to the app/pages/quizzes/quizzes-component.html file and modify it to the following:

<div class="quizzes container"> <h2>Take a Quiz</h2> <p>Test your knowledge of any of the following quiz you are familiar with.</p> <div class="quizzes__list"> <app-quiz-card></app-quiz-card> </div> </div>

Next, add the following styling to quizzes.component.css:

.quizzes { text-align: center; } .quizzes h2 { font-size: 34px; margin-top: 20px; } .quizzes p { color: rgb(73,80,87); margin-bottom: 20px; font-size: 18px; } .quizzes__list { display: flex; flex-wrap: wrap; justify-content: center; gap: 5px; margin: 0 auto; max-width: 1000px; } app-quiz-card { display: flex; }

With this, when we open our app in the browser, we will see the following:

image.png

Next, let’s work on the interface for the quiz page. Head over to the app/components/question.component.ts file and add the following import:

import { Input, Output, EventEmitter } from '@angular/core';

Next, to add the properties we will use later on. Add the following lines of code before the constructor in the QuestionComponent class:

@Input() question: any; @Input() questionNumber!:number; @Input() quiz: any; @Input() quizLength!:number; selectedOption = '' @Output() nextQuestion: EventEmitter<any> = new EventEmitter(); @Output() prevQuestion: EventEmitter<any> = new EventEmitter();

Next, in its HTML file question.component.html, add the following lines of code:

<div class="question container"> <h2>CSS Quiz</h2> <p>A simple quiz to test your CSS knowledge</p> <div class="question__body"> <h4>Which of this is a CSS framework</h4> <div class="question__bodyOpt"> <div><span>A.</span> Jquery</div> <div><span>B.</span> Bootstrap</div> <div><span>C.</span> SASS</div> <div><span>D.</span> Less</div> </div> <div class="question__btn"> <button><</button> <span>1/5</span> <button>></button> </div> </div> </div>

Next, add the following styles to the question.component.css file:

.question { margin-top: 30px; text-align: center; } .question h2 { font-size: 34px; } .question p { color: rgb(73,80,87); font-size: 18px; } .question__body { background-color: white; max-width: 800px; margin: 0 auto; margin-top: 20px; padding: 20px; } .question__body h4 { margin-bottom: 10px; } .question__bodyOpt { display: flex; flex-wrap: wrap; gap: 10px; } .question__bodyOpt > div { padding: 10px; flex-basis: calc(50% - 5px); flex-grow: 1; text-align: left; min-width: 200px; box-sizing: border-box; border: 1px solid gainsboro; cursor: pointer; } .question__bodyOpt > div:hover{ background-color: gainsboro; } .question__bodyOpt span { margin-right: 20px; } .question__btn { margin-top: 10px; display: flex; color: gray; justify-content: space-around; } .question__btn button { background-color: transparent; color: gray; border: 1px solid gray; border-radius: 10px; height: fit-content; padding: 3px 20px; } .question__btn button:hover{ background-color: rgb(248,249,250); } .question .question__submit { background-color: coral; padding: 5px 15px; color: white; border: none; } .question .question__submit:hover { background-color: rgb(254, 108, 55); } .selected { background-color: coral; color: white; }

Then head over to the app/pages/quiz/quiz.component.html file and modify it to the following:

<div class="quiz"> <app-question></app-question> </div>

With this, when you navigate to http://localhost:4200/quiz/1 in our browse we will see the following:

image (1).png

Next, let’s work on the interface for the score page. Head over the app/pages/score/score.component.html file and modify it to the following:

<div class="score container"> <h2>CSS Quiz</h2> <p>A simple quiz to test your CSS knowledge</p> <div class="score__body"> <h3>Congratulation!!!</h3> <p>Below are your details:</p> <div class="score__details"> <div> Total Questions Attempted: <span>5</span><br> Total Wrong Answered: <span>1</span><br> Total Correct Answers: <span>4</span><br> </div> <div> Score: <span> 4/5 </span> </div> </div> </div> </div>

Now add the following styles to the score.component.css file:

.score { margin-top: 30px; text-align: center; } .score h2 { font-size: 34px; } .score p { color: rgb(73,80,87); font-size: 18px; } .score__body { background-color: white; max-width: 800px; margin: 0 auto; margin-top: 20px; padding: 20px; } .score__details { display: flex; justify-content: space-between; } .score__details > div:first-child { text-align: left; color: rgb(73,80,87); line-height: 30px; } .score__details > div:first-child span { color: black; } .score__details > div:last-child span { display: block; font-size: 24px; padding: 20px; border-radius: 4px; background-color: coral; color: white; }

With this, when we navigate to http://localhost:4200/score in our browser we will see the following:

image (2).png

Initializing Apollo Client

To initialize Apollo Client so that we can start using it to interact with Webiny, we need to get the API token and the correct Headless CMS API endpoint. Once we get them we will store them as environment variables in the app/environments/environment.ts file as follows:

export const environment = { production: false, apiUrl: "<api-url-here>", apiToken: "<api-token-here>" };

Note: Both the API token and URL are sensitive information. After filling them out make sure not to commit them to Git history.

To get the API token, head over to the Webiny Admin app, in the sidebar, expand the Settings tab and we will see API keys under the ACCESS MANAGEMENT section. Click on it and we will see the following page:

image.png

Next, click on NEW API KEY and a prompt will appear where we can set up our API token. First, enter the name and description of the API token.

image (1).png

Next, scroll down to the Content tab, expand it and select All locales.

image (2).png

Next, scroll to the Headless CMS tab, expand it and make the following changes which include selecting the API type and model we the generated token to have access to.

image (3).png

image (4).png

Then click on the SAVE API KEY at the bottom of the page and the API token will be visible at the top of the page:

image (5).png

Copy and save it as an environment variable just as described above.

Next, let's get the endpoint. in the sidebar click on API Playground, then in the playground click on the Headless CMS - Read API tab at the top of the page, copy the URL directly below the tab and supply it as environment variable.

image (6).png

Now to initialize Apollo Client, head over to the src/app/graphql-module.ts file and modify it to the following:

import {NgModule} from '@angular/core'; import {APOLLO_OPTIONS} from 'apollo-angular'; import {ApolloClientOptions, InMemoryCache, ApolloLink } from '@apollo/client/core'; import {HttpLink} from 'apollo-angular/http'; import { setContext } from '@apollo/client/link/context'; import { environment } from './../environments/environment'; const uri = environment.apiUrl const auth = setContext(() => { return { headers: { Authorization: `Bearer ${environment.apiToken}` } } }) export function createApollo(httpLink: HttpLink): ApolloClientOptions<any> { return { link: ApolloLink.from([auth, httpLink.create({ uri })]), cache: new InMemoryCache(), }; } @NgModule({ providers: [ { provide: APOLLO_OPTIONS, useFactory: createApollo, deps: [HttpLink], }, ], }) export classOnChanges GraphQLModule {}

Next, in the src/app/app.module.ts file, add the following import:

import { ApolloModule } from 'apollo-angular';

Then, add ApolloModule to the import property:

imports: [ // ... ApolloModule, ],

With this, we can now start sending GraphQL requests to Webiny.

Fetching all Quiz

To do this first let’s create a service where all our GraphQL requests will be done. Enter the following command in the terminal:

ng g s services/quiz

This will create a quiz service in a services folder in app. Now, let’s write our first query which will be for fetching all quizzes in our CMS. In app/services/quiz.service.ts add the following import and query.

import { Apollo, gql } from 'apollo-angular' const GET_QUIZZES = gql`{ listQuizzes { data { id name description } } } `

Next, to inject Apollo into this service, modify the class constructor to the following:

constructor(private apollo: Apollo) { }

Next, add the following method after the constructor for sending query requests to get all quizzes.

getQuizzes() { return this.apollo.watchQuery<any>({ query: GET_QUIZZES }) }

To use this function, head over to app/pages/quizzes/quizzes.component.ts and add the following import:

import { QuizService } from 'src/app/services/quiz.service';

Then modify the QuizzesComponent to the following:

export class QuizzesComponent implements OnInit { quizzes = [] constructor(private quizService: QuizService) {} ngOnInit(): void { this.quizService.getQuizzes().valueChanges.subscribe(({data}) => { this.quizzes = data.listQuizzes.data }) } }

In the above code, we fetch our quizzes and store them in a quizzes array variable which will be iterated over in the template to display the quizzes.

Head over to the quizzes.component.html file and modify it to the following:

<div class="quizzes container"> <h2>Take a Quiz</h2> <p>Test your knowledge of any of the following quiz you are familiar with.</p> <div class="quizzes__list" *ngFor="let quiz of quizzes"> <app-quiz-card [quizData]="quiz"></app-quiz-card> </div> </div>

Next, modify the app/components/quiz-card/quiz-card.component.html file to the following:

<div class="quizCard"> <h3>{{quizData.name}}</h3> <p>{{quizData.description}}</p> <span>questions: <span>{{questionsLength}}</span></span> <button [routerLink]="['quiz', quizData.id]">Take quiz</button> </div>

With this, quizzes in our CMS should now be displayed. Right now if you notice the length of the questions displayed in the quiz card is 0 which is static. Let’s fix that.

To fix this, we will use the ID of a quiz to fetch all its questions and then display their length. Head over to app/services/quiz.services and add the following query after GET_QUIZZES:

const GET_QUESTIONS = gql` query GetQuestions($where:QuestionListWhereInput){ listQuestions(where: $where) { data { title option1 option2 option3 option4 answer } } } `

Next, add the following method for fetching all the questions of a quiz when the quiz id is passed to it getQuizzes:

getQuestions(id:string) { return this.apollo.watchQuery<any>({ query: GET_QUESTIONS, variables: { where: {ref: {id}} } }) }

Next, head over app/components/quiz-card/quiz-card.component.ts and import the quiz service:

import { QuizService } from 'src/app/services/quiz.service';

Next, modify the class constructor and ngOnInit method to the following:

constructor(private quizService: QuizService) {} ngOnInit(): void { this.quizService.getQuestions(this.quizData.id).valueChanges.subscribe(({data}) => { this.questionsLength = data.listQuestions.data.length }) }

The above code fetches all questions for a quiz and then modifies the questions variable to the length of the fetched questions. With this, the problem is solved.

Implementing the quiz functionality

If we click on the Take quiz button on a quiz in our app we will be taken to the quiz page. On the quiz page, all the questions for a quiz will be displayed in a paginated pattern, we will be able to select the answers to questions and submit the quiz to get the result. Right now it's just mock data that's been displayed with no functionalities included. Let’s work on that.

First, let’s replace the mock data with the one from our CMS and add the pagination functionality where we can go to the next or previous question if it exists by clicking a button.

Head over to the app/services/quiz.service.ts file let’s create a function to fetch the data for a single quiz so it can be used to replace the static on the quiz page. Add the following query after GET_QUESTIONS:

const GET_QUIZ = gql` query GetQuiz($where:QuizGetWhereInput!){ getQuiz(where: $where) { data { name description } } } `

Next, add the following lines of code after the getQuestions method:

getQuiz(id:string) { return this.apollo.watchQuery<any>({ query: GET_QUIZ, variables: { where: {id} } }) }

Next, head over to the app/pages/quiz/quiz.component.ts and add the following imports:

import { QuizService } from 'src/app/services/quiz.service'; import { ActivatedRoute } from '@angular/router';

Next, modify the QuizComponent to the following:

export class QuizComponent implements OnInit { quiz = []; quizLength = 0 questions = []; questionNumber = 0; id!:string; constructor( private quizService: QuizService, private route: ActivatedRoute ) { } goToNext() { this.questionNumber++ } goToPrevious() { this.questionNumber-- } ngOnInit(): void { this.id = this.route.snapshot.paramMap.get('id')! this.quizService.getQuestions(this.id) .valueChanges .subscribe(({data}) => { this.questions = data.listQuestions.data this.quizLength = data.listQuestions.data.length }) this.quizService.getQuiz(this.id) .valueChanges .subscribe(({data}) => { this.quiz = data.getQuiz.data }) } }

Above, in the ngOnInit method, we are fetching all questions and the quiz whose ID is attached as a parameter to the URL and storing the returned data in the corresponding properties.

We have also created a goToNext and goToPrevious method for increasing and decreasing the questionNumber property respectively. We are doing this because we will be using the questionNumber property to get a single question object in the questions array (questions[questionNumber]) which will be displayed in the UI. This way when one (1) is added questionNumber the next question will be displayed and when one (1) is subtracted, the previous question will be displayed creating the pagination functionality.

Next, modify its HTML file quiz.component.html to the following:

<div class="quiz"> <app-question [question]="questions[questionNumber]" [questionNumber]="questionNumber+1" [quiz]="quiz" [quizLength]="quizLength" (nextQuestion)="this.goToNext()" (prevQuestion)="this.goToPrevious()" ></app-question> </div>

Now head over to the app/components/question.component.html file and modify it to the following:

<div class="question container"> <h2>{{quiz?.name}}</h2> <p>{{quiz?.description}}</p> <div class="question__body"> <h4>{{question?.title}}</h4> <div class="question__bodyOpt"> <div *ngFor="let option of [ {label: 'A', value: question?.option1}, {label: 'B', value: question?.option2}, {label: 'C', value: question?.option3}, {label: 'D', value: question?.option4}, ]"> <span>{{option.label}}.</span>{{option.value}} </div> </div> <div class="question__btn"> <button (click)="this.prevQuestion.emit()" [disabled]="questionNumber === 1"><</button> <span>{{questionNumber}}/{{quizLength}}</span> <button (click)="this.nextQuestion.emit()" *ngIf="questionNumber !== quizLength" [disabled]="questionNumber === quizLength">></button> <button class="question__submit" *ngIf="questionNumber === quizLength"> Submit </button> </div> </div> </div>

With the above code, we are replacing the mock data with the one from our CMS, disabling the previous button when the first question is displayed and replacing the next button with a submit button when the last question is displayed.

Now let’s work on highlighting the selected option for a question. Head over the app/services/quiz/services.ts file and add the following property to the class:

answers: any[] = []

Next, add the following method after getQuiz method:

pickedAnswer(selectedOption:string, correctAnswer:string, questionNumber:number) { let alreadyAnswered = this.answers.filter(answer => ( Object.values(answer).includes(questionNumber) )).length if(alreadyAnswered === 0){ this.answers = [...this.answers, {questionNumber, selectedOption, correctAnswer}] }else { let answerIndex = this.answers.findIndex(answer => ( questionNumber === answer.questionNumber )) this.answers[answerIndex].selectedOption = selectedOption } }

The above method will be called whenever a question is answered. It will be used to store the selected option for the question, the correct answer to the question, and the question’s number as an object in the answers array property. So each answered question will be represented as an object in the answers array. Doing it this way will enable us to highlight the selected option for any question, by using its number to filter out the right object from answers then highlighting the option that is equal to the one in the object. Also, when we want to calculate the total score for a quiz we can compare the selected option for a question and the answer to the question present in every object in the answers array to find out which question was answered correctly.

Now to call the above function Head over to app/component/question/question.components.ts and first import the quiz service:

import { QuizService } from 'src/app/services/quiz.service';

Next, inject the service and add the following method:

constructor(private quizService: QuizService) { } selectOption(selectedOption:string, correctAnswer:string, questionNumber:number) { this.selectedOption = selectedOption this.quizService.pickedAnswer(selectedOption, correctAnswer, questionNumber) }

Next, in its HTML file question.component.html modify the div with the class name of question__bodyOpt to the following:

<div class="question__bodyOpt"> <div *ngFor="let option of [ {label: 'A', value: question?.option1}, {label: 'B', value: question?.option2}, {label: 'C', value: question?.option3}, {label: 'D', value: question?.option4}, ]" (click)="selectOption(option.value, question.answer, this.questionNumber)" [ngClass]="{selected: selectedOption === option.value}"> <span>{{option.label}}.</span>{{option.value}} </div> </div>

Above, we have attached a click event to every option which calls the selectOption method when clicked and we a conditional adding a selected class to add highlighting if the value of the selectedOption property equals the option. Since the selectOption method sets selectedOption to the value of the click option, whenever it's called that option will be highlighted. This works but it's not exactly how we want it to be, because right now if we select an option in another question and go back to the previous one we will see that its selected option is no longer highlighted, which is like that because the value of selectedOption has been changed since we clicked on another option.

To fix this, whenever we navigate to a question the selectedOption property has to be reset to the option that was selected. This is where the answers array property in the quiz service which is modified by the pickedAnswer method will be of use.

Add the following lines of code after selectOption in the QuestionComponent:

ngOnChanges() { let answer = this.quizService.answers.filter((answer) => ( this.questionNumber === answer.questionNumber )) this.selectedOption = answer[0]?.selectedOption }

In the above code, we are using the ngOnChanges lifecycle hook which runs anytime a data-bound property changes in order to reset the selectedOption property. With this anytime questionNumber (the next or previous button has been clicked) the above hook will run.

With this, the selected options will stay highlighted.

Calculating the score for a quiz

The score page will display the score of a question, the wrong answers, correct answers, and attempted questions. To get all these values and make them accessible in the score page, we will create a method in the quiz service that calculates these values and store them as properties in the service, then for accessing these properties in the score page we will create another method for that.

Head over to app/services/quiz.service.ts and add the following properties after the answers property:

attempts = 0 wrongAnswers = 0 correctAnswers = 0 quizLength = 0

Next, add the following methods after pickedAnswer:

score(quizLength:number) { this.quizLength = quizLength this.attempts = this.answers.length this.wrongAnswers = 0 this.answers.forEach((answer) => { if(answer.selectedOption.trim() !== answer.correctAnswer.trim()) { this.wrongAnswers++ }else{ this.correctAnswers++ } }) } getScore() { return { quizLength: this.quizLength, attempts: this.attempts, wrongAnswers: this.wrongAnswers, correctAnswers: this.correctAnswers } }

Next, head over app/components/question/question.component.ts and import router which will use to navigate to the score page when the a quiz is submitted :

import { Router } from '@angular/router';

Next, inject router by modifying the constructor to the following:

constructor(private quizService: QuizService, private router: Router) { }

Next, add the following method after selectOption when called will call the score method in the service then navigate to the score page.

score() { this.quizService.score(this.quizLength) this.router.navigate(['/score']); }

Now to call the above method, in the question.component.html file modify the<Submit> button into the following:

<button class="question__submit" (click)="score()" *ngIf="questionNumber === quizLength"> Submit </button>

Next, let’s display the scores and other values in the score page when a quiz is submitted. Head over to app/pages/score/component.ts and first import the quiz service:

import { QuizService } from 'src/app/services/quiz.service';

Next, add the following variable and modify the constructor an ngOnInit method to the following:

score: any; constructor(private quizService: QuizService) { } ngOnInit(): void { this.score = this.quizService.getScore() }

Finally, modify the score.component.html file to the following:

<div class="score container"> <h2>CSS Quiz</h2> <p>A simple quiz to test your knowledge of CSS (Cascading style sheets)</p> <div class="score__body"> <h3>Congratulation!!!</h3> <p>Below are your details:</p> <div class="score__details"> <div> Total Questions Attempted: <span>{{score.attempts}}</span><br> Total Wrong Answered: <span>{{score.wrongAnswers}}</span><br> Total Correct Answers: <span>{{score.correctAnswers}}</span><br> </div> <div> Score: <span> {{score.correctAnswers}}/{{score.quizLength}} </span> </div> </div> </div> </div>

With this, when we take a quiz and click on the submit button, we will be taken to the score page where we the results will be displayed

Conclusion

Quiz apps include features that require one to think logically in order to create them which makes it a great coding challenge for those starting out. In this tutorial, we have learned about Webiny CMS and how we can use it to build a quiz app where our data will be coming from a CMS rather than being hardcoded, giving us the liberty to update the questions and answers for a quiz by using a ready-to-use Admin page without having to update and redeploy our code.

Full source code: https://github.com/webiny/write-with-webiny/tree/main/tutorials/angular-quiz-app


This article was written by a contributor to the Write with Webiny program. Would you like to write a technical article like this and get paid to do so? Check out the Write with Webiny GitHub repo.

Find more articles on the topic of:angularbuild projectsquiz appcontributed articles

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