Node.js & Redis Caching

node_redis_cache.js

const express = require('express');
const fetch = require('node-fetch');
const redis = require('redis');

const PORT = process.env.PORT || 5000;
const REDIS_PORT = process.env.PORT || 6379;

const client = redis.createClient(REDIS_PORT);

const app = express();

// Set response
function setResponse(username, repos) {
  return `<h2>${username} has ${repos} Github repos</h2>`;
}

// Make request to Github for data
async function getRepos(req, res, next) {
  try {
    console.log('Fetching Data...');

    const { username } = req.params;

    const response = await fetch(`https://api.github.com/users/${username}`);

    const data = await response.json();

    const repos = data.public_repos;

    // Set data to Redis
    client.setex(username, 3600, repos);

    res.send(setResponse(username, repos));
  } catch (err) {
    console.error(err);
    res.status(500);
  }
}

// Cache middleware
function cache(req, res, next) {
  const { username } = req.params;

  client.get(username, (err, data) => {
    if (err) throw err;

    if (data !== null) {
      res.send(setResponse(username, data));
    } else {
      next();
    }
  });
}

app.get('/repos/:username', cache, getRepos);

app.listen(5000, () => {
  console.log(`App listening on port ${PORT}`);
});

I believe line 6 should be const REDIS_PORT = process.env.REDIS_PORT || 6379;
process.env.REDIS_PORT instead of process.env.PORT

I believe line 6 should be const REDIS_PORT = process.env.REDIS_PORT || 6379;
process.env.REDIS_PORT instead of process.env.PORT

That's true

You can also use console.time().

async function getRepos(req, res, next) {
  try {
    console.log('Fetching Data...');

    const { username } = req.params;
    console.time(`START time`);
    const response = await fetch(`https://api.github.com/users/${username}`);

    const data = await response.json();

    const repos = data.public_repos;

    // Set data to Redis
    client.setex(username, 3600, repos);

    res.send(setResponse(username, repos));

    console.timeEnd(`END time`);

  } catch (err) {
    console.error(err);
    res.status(500);
  }
}

And again:

console.time(`START GET time`);
    app.get('/repos/:username', cache, getRepos);
console.timeEnd(`END GET time`);

I believe line 6 should be const REDIS_PORT = process.env.REDIS_PORT || 6379;
process.env.REDIS_PORT instead of process.env.PORT

And also he should use the const PORT value instead of 5000 on line 57 to be like this app.listen(PORT, () => {

Yes, you are right. I pinned it as a comment on the video, I will change when I get the chance

Greetings! [thank you for everything so far, hopefully life makes all equal after all :D] how will this middleware deal with changes on the api data and so on? I mean, if the user creates a new repo.. what'd happen? At line 47, we're just checking if the cached data isn't null, not handling any comparison with api current data, right? Thanks in advance. [btw I'm getting my 2nd mern udemy course, thanks 4all again.]

Or, will try or/and async , await keywords handle this on the background? Thanks.

I believe line 6 should be const REDIS_PORT = process.env.REDIS_PORT || 6379;
process.env.REDIS_PORT instead of process.env.PORT

Correct, sorry about that

Do you have code samples accessing redis through aws elasticache ?

Thanks sir

This code did not work for me idk why! this error comes out

ClientClosedError: The client is closed

I have a same problem. The terminal it shows ClientClosedError: The client is closed. If I use await client.connect(), the system hangs

I have the same problem as @MartynCastagno

Resolved: Keep await client.connect()

Put data in a variable and await the response. See function:

async function cache(req, res, next) {
  const { username } = req.params;
  const data = await client.get(username);
  if (data !== null) {
    res.send(setResponse(username, data));
  } else {
    next();
  }
}

I solved the problem : "ClientClosedError: The client is closed"

1. Stating redis in the terminal:

   @pop-os:~$ redis-server

2. adding in the code: client.connect();

   that is:

   const client = redis.createClient(REDIS_PORT)
   client.connect();
   client.on('connect', () => {
   console.log('connected');
   });

@MoAboabdo

This code did not work for me idk why! this error comes out
ClientClosedError: The client is closed

try to downgrade your redis and node-fetch packages. It will solve your issue, I have the same issue, now works fine.

my case const fetch = require('node-fetch') is not working

my case const fetch = require('node-fetch') is not working

Instal the used version so you don't have to worry about importing it in a different way.
npm i [email protected]