wip chapter 7

07-creational-design-patterns/10-dependency-injection/.gitignore

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+data.sqlite

07-creational-design-patterns/10-dependency-injection/README.md

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+# 10-dependency-injection
+
+This example shows how to wire dependencies using the dependency injection
+pattern
+
+## Dependencies
+
+Install all necessary dependencies with:
+
+```shell script
+npm install
+```
+
+## Run
+
+To run the example:
+
+```shell script
+node import-posts.js
+node index.js
+```

07-creational-design-patterns/10-dependency-injection/blog.js

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+export class Blog {
+  constructor(db) {
+    this.db = db
+  }
+
+  initialize() {
+    const initQuery = `CREATE TABLE IF NOT EXISTS posts (
+      id TEXT PRIMARY KEY,
+      title TEXT NOT NULL,
+      content TEXT,
+      created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+    );`
+
+    return this.db.run(initQuery)
+  }
+
+  createPost(id, title, content, createdAt) {
+    return this.db.run(
+      'INSERT INTO posts VALUES (?, ?, ?, ?)',
+      id,
+      title,
+      content,
+      createdAt
+    )
+  }
+
+  getAllPosts() {
+    return this.db.all('SELECT * FROM posts ORDER BY created_at DESC')
+  }
+}

07-creational-design-patterns/10-dependency-injection/db.js

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+import { open } from 'sqlite'
+import sqlite3 from 'sqlite3'
+
+export function createDb(filename) {
+  return open({
+    filename,
+    driver: sqlite3.Database,
+  })
+}

07-creational-design-patterns/10-dependency-injection/import-posts.js

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+import { join } from 'node:path'
+import { Blog } from './blog.js'
+import { createDb } from './db.js'
+
+const posts = [
+  {
+    id: 'my-first-post',
+    title: 'My first post',
+    content: 'Hello World!\nThis is my first post',
+    // biome-ignore lint/style/useNamingConvention: db mapping
+    created_at: new Date('2020-02-03'),
+  },
+  {
+    id: 'iterator-patterns',
+    title: 'Node.js iterator patterns',
+    content: "Let's talk about some iterator patterns in Node.js\n\n...",
+    // biome-ignore lint/style/useNamingConvention: db mapping
+    created_at: new Date('2020-02-06'),
+  },
+  {
+    id: 'dependency-injection',
+    title: 'Dependency injection in Node.js',
+    content:
+      'Today we will discuss about dependency injection in Node.js\n\n...',
+    // biome-ignore lint/style/useNamingConvention: db mapping
+    created_at: new Date('2020-02-29'),
+  },
+  // ...
+]
+
+const db = await createDb(join(import.meta.dirname, 'data.sqlite'))
+const blog = new Blog(db)
+await blog.initialize()
+
+await Promise.all(
+  posts.map(post =>
+    blog.createPost(post.id, post.title, post.content, post.created_at)
+  )
+)
+console.log('All posts imported')

07-creational-design-patterns/10-dependency-injection/index.js

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+import { join } from 'node:path'
+import { Blog } from './blog.js'
+import { createDb } from './db.js'
+
+const db = await createDb(join(import.meta.dirname, 'data.sqlite'))
+const blog = new Blog(db)
+await blog.initialize()
+const posts = await blog.getAllPosts()
+if (posts.length === 0) {
+  console.log(
+    'No post available. Run `node import-posts.js`' +
+      ' to load some sample posts'
+  )
+}
+
+for (const post of posts) {
+  console.log(post.title)
+  console.log('-'.repeat(post.title.length))
+  console.log(`Published on ${new Date(post.created_at).toISOString()}`)
+  console.log(post.content)
+}

07-creational-design-patterns/10-dependency-injection/package.json

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+{
+  "name": "10-dependency-injection",
+  "version": "1.0.0",
+  "description": "This example shows how to wire dependencies using the dependency injection pattern",
+  "type": "module",
+  "scripts": {},
+  "engines": {
+    "node": ">=22"
+  },
+  "engineStrict": true,
+  "keywords": [],
+  "author": "Luciano Mammino and Mario Casciaro",
+  "license": "MIT",
+  "dependencies": {
+    "sqlite": "^5.1.1",
+    "sqlite3": "^5.1.7"
+  }
+}