Build a powerful image upload API: using Node.js, Multer and PostgreSQL

This article will guide you on how to use Node.js, Multer and PostgreSQL to build a simple and easy-to-use API to implement single and multiple image upload functions. Image uploading and database storage can be easily completed without complicated configuration.

Prerequisites:

• Node.js and PostgreSQL are installed and configured.
• Familiar with the basic operations of Node.js and PostgreSQL.
• Postman for API testing.

Project settings:

1. Create a project directory and initialize it:

   mkdir imageUpload
   cd imageUpload
   npm init -y

2. Install dependencies:

   npm install express multer body-parser pg

3. Create directory structure:

   <code>imageUpload/
   ├── index.js
   ├── images/
   ├── db/
   │   └── db.js
   └── routes/
       └── image_routes.js
   └── controllers/
       └── upload.js</code>

4. Create PostgreSQL database and user tables:

   CREATE DATABASE uploader;
   CREATE TABLE users (id SERIAL PRIMARY KEY, name VARCHAR(50) NOT NULL, icon VARCHAR NOT NULL);

Code implementation:

1. Database connection (db.js):

   const { Client } = require('pg');
   const client = new Client({
       user: 'postgres',
       host: 'localhost',
       database: 'uploader',
       password: 'YOUR_PASSWORD', // 請?zhí)鎿Q為您的數(shù)據(jù)庫密碼
       port: 5432,
   });
   client.connect().then(() => console.log("Connected to DB")).catch(err => console.error("數(shù)據(jù)庫連接失敗:", err.message));
   module.exports = client;

2. Express Server (index.js):

   const express = require('express');
   const bodyParser = require('body-parser');
   const app = express();
   const port = process.env.PORT || 4000;
   
   app.use(bodyParser.json());
   app.use(bodyParser.urlencoded({ extended: true }));
   app.use('/images', express.static('images')); // 設(shè)置靜態(tài)文件目錄
   
   require('./routes/image_routes')(app);
   
   app.listen(port, () => {
       console.log(`服務(wù)器運(yùn)行在端口 ${port}`);
   });

3. Route definition (image_routes.js):

   const express = require('express');
   const uploadController = require('../controllers/upload');
   
   module.exports = (app) => {
       app.post('/upload/single', uploadController.upload.single('icon'), uploadController.uploadSingleImage);
       app.post('/upload/multiple', uploadController.upload.array('icon', 12), uploadController.uploadMultipleImage);
   };

4. Image upload controller (upload.js):

   const multer = require('multer');
   const path = require('path');
   const client = require('../db/db');
   
   const storage = multer.diskStorage({
       destination: (req, file, cb) => cb(null, './images'),
       filename: (req, file, cb) => cb(null, `image-${Date.now()}${path.extname(file.originalname)}`),
   });
   
   const fileFilter = (req, file, cb) => {
       if (!file.originalname.match(/\.(jpg|jpeg|png)$/i)) {
           return cb(new Error('請上傳 JPG, JPEG 或 PNG 格式的圖片'), false);
       }
       cb(null, true);
   };
   
   exports.upload = multer({ storage, fileFilter });
   
   exports.uploadSingleImage = async (req, res) => {
       try {
           await client.query(`INSERT INTO users (name, icon) VALUES ('${req.body.name}', '${req.file.filename}')`);
           res.json({ statusCode: 200, status: true, message: '圖片上傳成功' });
       } catch (error) {
           console.error("圖片上傳失敗:", error);
           res.status(500).json({ statusCode: 500, status: false, message: '圖片上傳失敗' });
       }
   };
   
   exports.uploadMultipleImage = async (req, res) => {
       try {
           for (const file of req.files) {
               await client.query(`INSERT INTO users (name, icon) VALUES ('${req.body.name}', '${file.filename}')`);
           }
           res.json({ statusCode: 200, status: true, message: '所有圖片上傳成功' });
       } catch (error) {
           console.error("圖片上傳失敗:", error);
           res.status(500).json({ statusCode: 500, status: false, message: '圖片上傳失敗' });
       }
   };
   

Test:

Use Postman to send a POST request to /upload/single or /upload/multiple, attaching the image file and username data.

Please note that YOUR_PASSWORD in the above code needs to be replaced with your PostgreSQL database password. Error handling has been enhanced to provide clearer error messages. Image format verification is also more stringent. Finally, remember to make the images folder images accessible.

This revised response provides a more robust and secure solution, including error handling and improved clarity. Remember to replace placeholders like YOUR_PASSWORD with your actual credentials.

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