How to update the cache when delete, update or add data? - node.js

Question

I use cache-all for data caching. Suppose need to add new information. It is added, and when a request to display all data occurs, new information is not displayed among all data. And so that the new data added also become displayed in the request, need to wait until the cache storage timer disappears. How can you make the cache update when you add, update, or delete data?
index.js:
const cache = require('cache-all')
cache.init({
expireIn: 90,
isEnable: true
})
app.listen(port, () => {
console.log(`Server has been started on ${port}`)
})
route:
const cache = require('cache-all')
router.get('/get_all', cache.middleware(90), controller.getAll)
Or advise the normal module for data caching but that it was easy to use.

Answer 1

you've stumbled upon one of the greatest problems in computer science, "Cache Invalidation".
The approach will greatly depend on your application, but usually a good way to get going is to manually invalidate the cache when you know you've changed it. For example, if you cache user profiles, you might use this on a /user/:user_id call to get that users profile. To invalidate the cache (or update it) you would remove the cache entry when a call is made that changes the users profile. Here's some pseudo code to illustrate.
const cache = require('cache-all');
router.get('/user/:username', (req, res) => {
const username = req.params.username;
return cache.get('user:'+username).then(userProfile => {
if (!userProfile) {
// There were no entries in the cache, so we had a "cache miss".
// We will need to look this up in the database, then potentially
// add it to the cache after.
}
return res.json(userProfile);
});
});
router.patch('/user/:username', (req, res) => {
const username = req.params.username;
const profileChanges = req.body.profile;
let profileToReturn = {};
return database.user.update(username, profileChanges).then(newProfile => {
profileToReturn = newProfile;
// We have updated something we know will be in the cache, so we need
// to either invalidate it (removing the entry) or update it. In this
// case we've decided to update the cache since we think it'll be used
// again very quickly.
return cache.set('user:'+username, profileToReturn);
}).then(cacheResult => {
return res.json(profileToReturn);
});
})
You can see from this example we have two endpoints, one which reads from the cache if it can (otherwise it goes to the database). And one which updates a value, and also updates the cache. Much of this will be up to your application, your reasons for caching, your load, etc. But this should help you along.

Answer 2

Can't you use cache.set('foo', 'bar') to set the new value? Would that not update the cache?