Bad example for Open/Closed Principle

src/admin.ts

@@ -0,0 +1,3 @@
+import User from './user';
+
+export default class Admin extends User {}

src/application.ts

@@ -1,14 +1,31 @@
+import Admin from './admin';
 import Article from './article';
 import ArticleJsonFactory from './article.json.factory';
 import ArticleRepository from './article.repository';
+import Contributor from './contributor';
 import Database from './database';
+import { UserType } from './types';
+import User from './user';
 
 export default class Application {
   run(): number {
     try {
       const database = new Database();
       const articleRepository = new ArticleRepository(database);
-      const article = new Article('Mon premier article');
+
+      const userPseudo = 'pierre';
+      const userType: UserType = 'admin';
+
+      const user: User = (() => {
+        switch (userType as UserType) {
+          case 'admin':
+            return new Admin(userPseudo);
+          case 'contributor':
+            return new Contributor(userPseudo);
+        }
+      })();
+
+      const article = new Article(user, 'Mon premier article');
 
       articleRepository.save(article);
 

src/article.json.factory.ts

@@ -5,6 +5,7 @@ export default class ArticleJsonFactory {
   static createFromArticle(article: Article): ArticleJson {
     return {
       title: article.getTitle(),
+      creatorPseudo: article.getCreator().getPseudo(),
     };
   }
 }

src/article.repository.ts

@@ -5,6 +5,6 @@ export default class ArticleRepository {
   constructor(private database: Database) {}
 
   save(article: Article): void {
-    this.database.save({ title: article.getTitle() }, 'articles');
+    this.database.save(article, 'articles');
   }
 }

src/article.ts

@@ -1,7 +1,13 @@
+import User from './user';
+
 export default class Article {
-  constructor(private title: string) {}
+  constructor(private creator: User, private title: string) {}
 
   getTitle(): string {
     return this.title;
   }
+
+  getCreator(): User {
+    return this.creator;
+  }
 }

src/contributor.ts

@@ -0,0 +1,3 @@
+import User from './user';
+
+export default class Contributor extends User {}

src/database.ts

@@ -3,7 +3,7 @@ export default class Database {
     console.log('On ouvre une connection à notre base de données MySQL');
   }
 
-  save(rowData: any, table: string): void {
+  save<T>(rowData: T, table: string): void {
     console.log(
       `On enregistre cette nouvelle donnée dans la table "${table}" de notre base de données MySQL`,
       rowData,

src/types.ts

@@ -1,3 +1,6 @@
 export type ArticleJson = {
   title: string;
+  creatorPseudo: string;
 };
+
+export type UserType = 'admin' | 'contributor';

src/user.ts

@@ -0,0 +1,7 @@
+export default class User {
+  constructor(private pseudo: string) {}
+
+  getPseudo(): string {
+    return this.pseudo;
+  }
+}