I am trying to make rest web service in nodejs and using redis for caching purpose to improve performance. I want to save as a object like offer which has id, offer name and vendor.
I do not want to have different key to have for all these. What is the way to do in a single key.
app.get('/insertOffers', function(req, res) {
const {id, offerName, offerVendor} = req.query;
client.set('offers', ) // client is my redis client
});
As @drdaeman says in the comment, using a Redis Hash offers you the ability to query a single key, where the sub-keys or hash keys is a unique key. The command would look something like the following:
HSET offerId offerJSONString
HGET offerId offerJSONString
So in your express function, you could do something like:
app.get('/insertOffers', function(req, res) {
let offer = {
id: req.query.id,
offerName: req.query.offerName,
offerVendor: req.query.offerVendor
}
client.hset('offers', offer.id, JSON.stringify(offer), yourCallbackFunction);
});
Note, you when you get the data, you will need to JSON.parse it.
client.hget('offers', offerId, function(err, offer){
let offer = JSON.parse(offer);
// do something with offer
})
I think the preference for a single key can be valid, like if you want to later delete all the offers with a single command, without a lookup. Redis is really fast though, so there shouldn't be a heavy performance cost to 2 round trips to the redis server.
client.set('offer:{id}', JSON.stringify({name:offerName, vendor:offerVendor})); and client.get('offer:{id}', function(err, reply) { console.log(reply); })
let offer = { id: req.query.id, offerName: req.query.offerName, offerVendor: req.query.offerVendor } client.hset('offer', offer.id, JSON.stringify(offer)); and getting this node_redis: Deprecated: The HSET command contains a "undefined" argument. This is converted to a "undefined" string now and will return an error from v.3.0 on. Please handle this in your code to make sure everything works as you intended it to.redis.print as the 4th argument, like on the hset example github page
HGET/HSET) instead ofGET/SET. However, there is a drawback that hash items can't have independent expire times. And normally there's really no harm in having a lot of keys in Redis, so using something likeclient.set(`offers:{id}`, JSON.stringify({name: offerName, vendor: offerVendor}))should be the way to go.client.set('offer:{id}', JSON.stringify({name:offerName, vendor:offerVendor}));it worked but when I am trying to get offer id wise then it does not work. Whatever id I pass it always return same last saved result. not id wise. can you please suggest how should I implement in such a way when I passclient.get('offer:{id}', function(err, reply) { console.log(reply); })then it should offer id wise. I think it is overriding last data in offers not saving id wise also