Node.js应用使用Redis客户端缓存时遭遇ClientClosedError问题求助

问题场景 #

以下是我Node.js项目index.js中的代码：

const express = require('express');
const axios = require('axios');
const cors = require('cors');
const redis = require('redis');

const port = 3000;
const DEFAULT_EXPIRATION = 3600;

const redisClient = redis.createClient();

redisClient.on('error', (error) => {
    console.error('Redis error:', error);
});

redisClient.on('connect', () => {
    console.log('Connected to Redis server');
});

const app = express();
app.use(cors());

app.get("/photos", async (req, res) => {
    try {
        const albumId = req.query.albumId;
        const { data } = await axios.get(
            "https://jsonplaceholder.typicode.com/photos",
            { params: { albumId } }
        );

        redisClient.set('photos', JSON.stringify(data));
        redisClient.expire('photos', DEFAULT_EXPIRATION);

        res.json(data);
    } catch (error) {
        console.error("Error fetching photos:", error);
        res.status(500).json({ error: "Failed to fetch photos" });
    }
});

app.get("/photos/:id", async (req, res) => {
    try {
        const photoId = req.params.id;
        const { data } = await axios.get(
            `https://jsonplaceholder.typicode.com/photos/${photoId}`
        );

        res.json(data);
    } catch (error) {
        console.error("Error fetching photo:", error);
        res.status(500).json({ error: "Failed to fetch photo" });
    }
});

app.listen(port, () => {
    console.log(`Server running on port ${port}`);
});

运行时触发如下错误：

return Promise.reject(new errors_1.ClientClosedError());
^
ClientClosedError: The client is closed

已导入createClient方法，但问题未解决，需要排查并修复。

问题原因及修复方案 #

原因 #

Redis v4+版本中，createClient()创建实例后不会自动连接，必须手动调用connect()方法；同时旧版的connect事件监听也不再适用，需要改用ready事件。

修复步骤 #

1. 手动调用connect()并处理连接逻辑
   将Redis客户端的初始化代码修改为异步方式，确保连接成功后再启动Express服务：

   const redisClient = redis.createClient();
   
   // 替换connect事件为ready事件
   redisClient.on('ready', () => {
       console.log('Connected to Redis server');
       // 连接成功后启动服务
       app.listen(port, () => {
           console.log(`Server running on port ${port}`);
       });
   });
   
   redisClient.on('error', (error) => {
       console.error('Redis error:', error);
   });
   
   // 手动触发连接
   (async () => {
       try {
           await redisClient.connect();
       } catch (err) {
           console.error('Failed to connect to Redis:', err);
           process.exit(1); // 连接失败时退出进程
       }
   })();
   

2. 使用Promise/async-await处理Redis命令
   Redis v4+的命令返回Promise，建议改用await确保命令执行成功，避免因客户端未就绪导致的错误：
   在/photos接口中修改Redis操作：

   // 替换原有的set和expire为await方式，直接设置过期时间
   await redisClient.set('photos', JSON.stringify(data), {
       EX: DEFAULT_EXPIRATION
   });
   

3. 可选：指定Redis连接参数
   如果Redis服务不在本地默认端口，需要在createClient中传入配置：

   const redisClient = redis.createClient({
       url: 'redis://localhost:6379' // 根据实际地址修改
   });
   

完整修复后的代码示例 #

const express = require('express');
const axios = require('axios');
const cors = require('cors');
const redis = require('redis');

const port = 3000;
const DEFAULT_EXPIRATION = 3600;

const redisClient = redis.createClient();

redisClient.on('ready', () => {
    console.log('Connected to Redis server');
    app.listen(port, () => {
        console.log(`Server running on port ${port}`);
    });
});

redisClient.on('error', (error) => {
    console.error('Redis error:', error);
});

(async () => {
    try {
        await redisClient.connect();
    } catch (err) {
        console.error('Failed to connect to Redis:', err);
        process.exit(1);
    }
})();

const app = express();
app.use(cors());

app.get("/photos", async (req, res) => {
    try {
        const albumId = req.query.albumId;
        const { data } = await axios.get(
            "https://jsonplaceholder.typicode.com/photos",
            { params: { albumId } }
        );

        await redisClient.set('photos', JSON.stringify(data), {
            EX: DEFAULT_EXPIRATION
        });

        res.json(data);
    } catch (error) {
        console.error("Error fetching photos:", error);
        res.status(500).json({ error: "Failed to fetch photos" });
    }
});

app.get("/photos/:id", async (req, res) => {
    try {
        const photoId = req.params.id;
        const { data } = await axios.get(
            `https://jsonplaceholder.typicode.com/photos/${photoId}`
        );

        res.json(data);
    } catch (error) {
        console.error("Error fetching photo:", error);
        res.status(500).json({ error: "Failed to fetch photo" });
    }
});

内容的提问来源于stack exchange，提问作者Gokul Srinivas