使用 Prisma、Express、TypeScript 和 PostgreSQL 來建立 RESTful API

目錄

1. 簡介

   • Prisma、Express、TypeScript 和 PostgreSQL 概述
   • 為什麼 Prisma 作為 ORM？
   • 設定環境

2. 初始項目設定

   • 設定新的 Node.js 專案
   • 配置 TypeScript
   • 安裝所需的軟體包

3. 設定 PostgreSQL

   • 安裝 PostgreSQL
   • 建立新資料庫
   • 配置環境變數

4. 設定 Prisma

   • 安裝 Prisma
   • 在專案中初始化 Prisma
   • 配置 Prisma 架構

5. 定義資料模型

   • 了解 Prisma 架構語言 (PSL)
   • 為 API 建立模型
   • 使用 Prisma 進行遷移

6. 將 Prisma 與 Express 整合

   • 設定 Express 伺服器
   • 使用 Prisma 建立 CRUD 操作
   • 錯誤處理與驗證

7. 使用 TypeScript 實作型別安全性

   • 使用 Prisma 定義型別
   • 類型安全的查詢與突變
   • 在 API 開發中利用 TypeScript

8. 測試 API

   • 為 Prisma 模型編寫單元檢定
   • 使用 Supertest 和 Jest 進行整合測試
   • 使用 Prisma 模擬資料庫

9. 部署注意事項

   • 為生產準備 API
   • 部署 PostgreSQL
   • 部署 Node.js 應用程式

10. 結論

    • 將 Prisma 與 Express 和 TypeScript 結合使用的好處
    • 最終想法與後續步驟

---

一、簡介

Prisma、Express、TypeScript 和 PostgreSQL 概述

在現代 Web 開發中，建立健壯、可擴展且類型安全的 API 至關重要。結合 Prisma 作為 ORM、Express 用於伺服器端邏輯、TypeScript 用於靜態類型以及 PostgreSQL 作為可靠的資料庫解決方案的強大功能，我們可以創建強大的 RESTful API。

Prisma 透過提供支援類型安全性查詢、遷移和無縫資料庫模式管理的現代 ORM 來簡化資料庫管理。 Express 是一個最小且靈活的 Node.js Web 應用程式框架，為 Web 和行動應用程式提供了一組強大的功能。 TypeScript 為 JavaScript 添加了靜態類型定義，有助於在開發過程的早期捕獲錯誤。 PostgreSQL 是一個功能強大的開源關係型資料庫系統，以其可靠性和功能集而聞名。

為什麼 Prisma 作為 ORM？

Prisma 與 Sequelize 和 TypeORM 等傳統 ORM 相比具有多種優點：

• 類型安全的資料庫查詢：自動產生的類型確保您的資料庫查詢是類型安全且無錯誤的。
• 自動遷移： Prisma 提供強大的遷移系統，讓您的資料庫架構與 Prisma 架構保持同步。
• 直覺的資料建模： Prisma 架構檔案（以 PSL 編寫）易於理解和維護。
• 廣泛的生態系統： Prisma 與其他工具和服務無縫集成，包括 GraphQL、REST API 和 PostgreSQL 等流行資料庫。

設定環境

在我們深入研究程式碼之前，請確保您的電腦上安裝了以下工具：

• Node.js（推薦LTS版本）
• npm 或 Yarn（用於套件管理）
• TypeScript（用於靜態型別）
• PostgreSQL（作為我們的資料庫）

安裝這些工具後，我們就可以開始建立我們的 API。

---

2. 初始項目設定

設定新的 Node.js 項目

1. 建立一個新的專案目錄：

   mkdir prisma-express-api
   cd prisma-express-api

1. 初始化一個新的 Node.js 專案：

   npm init -y

這將在您的專案目錄中建立一個 package.json 檔案。

配置 TypeScript

1. 安裝 TypeScript 和 Node.js 類型：

   npm install typescript @types/node --save-dev

1. 在專案中初始化 TypeScript：

   npx tsc --init

此指令建立一個 tsconfig.json 文件，它是 TypeScript 的設定檔。根據您的項目需要對其進行修改。這是基本設定：

   {
     "compilerOptions": {
       "target": "ES2020",
       "module": "commonjs",
       "strict": true,
       "esModuleInterop": true,
       "skipLibCheck": true,
       "forceConsistentCasingInFileNames": true,
       "outDir": "./dist"
     },
     "include": ["src/**/*"]
   }

1. 建立專案結構：

   mkdir src
   touch src/index.ts

安裝所需的套件

要開始使用 Express 和 Prisma，您需要安裝一些必要的軟體包：

npm install express prisma @prisma/client
npm install --save-dev ts-node nodemon @types/express

• express: The web framework for Node.js.
• prisma: The Prisma CLI for database management.
• @prisma/client: The Prisma client for querying the database.
• ts-node: Runs TypeScript directly without the need for precompilation.
• nodemon: Automatically restarts the server on file changes.
• @types/express: TypeScript definitions for Express.

---

3. Setting Up PostgreSQL

Installing PostgreSQL

PostgreSQL can be installed via your operating system’s package manager or directly from the official website. For example, on macOS, you can use Homebrew:

brew install postgresql
brew services start postgresql

Creating a New Database

Once PostgreSQL is installed and running, you can create a new database for your project:

psql postgres
CREATE DATABASE prisma_express;

Replace prisma_express with your preferred database name.

Configuring Environment Variables

To connect to the PostgreSQL database, create a .env file in your project’s root directory and add the following environment variables:

DATABASE_URL="postgresql://<user>:<password>@localhost:5432/prisma_express"

Replace and with your PostgreSQL username and password. This connection string will be used by Prisma to connect to your PostgreSQL database.

---

4. Setting Up Prisma

Installing Prisma

Prisma is already installed in the previous step, so the next step is to initialize it within the project:

npx prisma init

This command will create a prisma directory containing a schema.prisma file and a .env file. The .env file should already contain the DATABASE_URL you specified earlier.

Configuring the Prisma Schema

The schema.prisma file is where you'll define your data models, which will be used to generate database tables.

Here’s a basic example schema:

generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

model User {
  id        Int      @id @default(autoincrement())
  name      String
  email     String   @unique
  createdAt DateTime @default(now())
  posts     Post[]
}

model Post {
  id        Int      @id @default(autoincrement())
  title     String
  content   String?
  published Boolean  @default(false)
  authorId  Int
  author    User     @relation(fields: [authorId], references: [id])
}

In this schema, we have two models: User and Post. Each model corresponds to a database table. Prisma uses these models to generate type-safe queries for our database.

---

5. Defining the Data Model

Understanding Prisma Schema Language (PSL)

Prisma Schema Language (PSL) is used to define your database schema. It's intuitive and easy to read, with a focus on simplicity. Each model in the schema represents a table in your database, and each field corresponds to a column.

Creating Models for the API

In the schema defined earlier, we created two models:

• User: Represents users in our application.
• Post: Represents posts created by users.

Migrations with Prisma

To apply your schema changes to the database, you’ll need to run a migration:

npx prisma migrate dev --name init

This command will create a new migration file and apply it to your database, creating the necessary tables.

---

6. Integrating Prisma with Express

Setting Up the Express Server

In your src/index.ts, set up the basic Express server:

import express, { Request, Response } from 'express';
import { PrismaClient } from '@prisma/client';

const app = express();
const prisma = new PrismaClient();

app.use(express.json());

app.get('/', (req: Request, res: Response) => {
  res.send('Hello, Prisma with Express!');
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

This code sets up a simple Express server and initializes the Prisma client.

Creating CRUD Operations with Prisma

Next, let’s create some CRUD (Create, Read, Update, Delete) routes for our User model.

Create a new user:

app.post('/user', async (req: Request, res: Response) => {
  const { name, email } = req.body;
  const user = await prisma.user.create({
    data: { name, email },
  });
  res.json(user);
});

Read all users:

app.get('/users', async (req: Request, res: Response) => {
  const users = await prisma.user.findMany();
  res.json(users);
});

Update a user:

app.put('/user/:id', async (req: Request, res: Response) => {
  const { id } = req.params;
  const { name, email } = req.body;
  const user = await prisma.user.update({
    where: { id: Number(id) },
    data: { name, email },
  });
  res.json(user);
});

Delete a user:

app.delete('/user/:id', async (req: Request, res: Response) => {
  const { id } = req.params;
  const user = await prisma.user.delete({
    where: { id: Number(id) },
  });
  res.json(user);
});

Error Handling and Validation

To enhance the robustness of your API, consider adding error handling and validation:

app.post('/user', async (req: Request, res: Response) => {
  try {
    const { name, email } = req.body;
    if (!name || !email) {
      return res.status(400).json({ error: 'Name and email are required' });
    }
    const user = await prisma.user.create({
      data: { name, email },
    });
    res.json(user);
  } catch (error) {
    res.status(500).json({ error: 'Internal Server Error' });
  }
});

---

7. Using TypeScript for Type Safety

Defining Types with Prisma

Prisma automatically generates TypeScript types for your models based on your schema. This ensures that your database queries are type-safe.

For example, when creating a new user, TypeScript will enforce the shape of the data being passed:

const user = await prisma.user.create({
  data: { name, email }, // TypeScript ensures 'name' and 'email' are strings.
});

Type-Safe Queries and Mutations

With TypeScript, you get autocomplete and type-checking for all Prisma queries, reducing the chance of runtime errors:

const users: User[] = await prisma.user.findMany();

Leveraging TypeScript in API Development

Using TypeScript throughout your API development helps catch potential bugs early, improves code readability, and enhances overall development experience.

---

8. Testing the API

Writing Unit Tests for Prisma Models

Testing is an essential part of any application development. You can write unit tests for your Prisma models using a testing framework like Jest:

npm install jest ts-jest @types/jest --save-dev

Create a jest.config.js file:

module.exports = {
  preset: 'ts-jest',
  testEnvironment: 'node',
};

Example test for creating a user:

import { PrismaClient } from '@prisma/client';

const prisma = new PrismaClient();

test('should create a new user', async () => {
  const user = await prisma.user.create({
    data: {
      name: 'John Doe',
      email: 'john.doe@example.com',
    },
  });
  expect(user).toHaveProperty('id');
  expect(user.name).toBe('John Doe');
});

Integration Testing with Supertest and Jest

You can also write integration tests using Supertest:

npm install supertest --save-dev

Example integration test:

import request from 'supertest';
import app from './app'; // Your Express app

test('GET /users should return a list of users', async () => {
  const response = await request(app).get('/users');
  expect(response.status).toBe(200);
  expect(response.body).toBeInstanceOf(Array);
});

Mocking the Database with Prisma

For testing purposes, you might want to mock the Prisma client. You can do this using tools like jest.mock() or by creating a mock instance of the Prisma client.

---

9. Deployment Considerations

Preparing the API for Production

Before deploying your API, ensure you:

• Remove all development dependencies.
• Set up environment variables correctly.
• Optimize the build process using tools like tsc and webpack.

Deploying PostgreSQL

You can deploy PostgreSQL using cloud services like AWS RDS, Heroku, or DigitalOcean. Make sure to secure your database with proper authentication and network settings.

Deploying the Node.js Application

For deploying the Node.js application, consider using services like:

• Heroku: For simple, straightforward deployments.
• AWS Elastic Beanstalk: For more control over the infrastructure.
• Docker: To containerize the application and deploy it on any cloud platform.

---

10. Conclusion

Benefits of Using Prisma with Express and TypeScript

Using Prisma as an ORM with Express and TypeScript provides a powerful combination for building scalable, type-safe, and efficient RESTful APIs. With Prisma, you get automated migrations, type-safe queries, and an intuitive schema language, making database management straightforward and reliable.

Congratulations!! You've now built a robust RESTful API using Prisma, Express, TypeScript, and PostgreSQL. From setting up the environment to deploying the application, this guide covered the essential steps to get you started. As next steps, consider exploring advanced Prisma features like nested queries, transactions, and more complex data models.

Happy coding!

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