node.js how to get data from redis database inside in middleware - node.js

Question

I'm doing middleware module that will extract data from redis and put to req.my_session.[here]
This is function that call inside app.use();
function parse_cookies(req){
if(req.headers.cookie != null){
var result = req.headers.cookie.match(new RegExp('m:[^=]*=[^; ]*', 'ig'));
if(result != null){
for(var i = 0; i < result.length; i++){
var result1 = result[i].split('=');
req.my_session[result1[0].substr(2)] = result1[1];
// get from redis value
client.get('sess:'+result1[1], function(err, reply) {
// reply is null when the key is missing
console.log(reply);
let li = i;
req.my_session[result1[0].substr(2)] = reply;
console.log('li = ' + li);
console.log('result1.lenght= ' + result.length);
if(i == result.length){
console.log('call the next');
}
});
}
}
}
} // parse_cookies
in console i outputs always 3, how can I get all data from database using redis.get and on last data call next() function for get out from my function?
problem it's get data from database in my middleware, I can't because redis has callback function
client.get("missingkey", function(err, reply) {
// reply is null when the key is missing
console.log(reply);
});

Answer 1

I think the issue is becuase of async in loop you can try the following
function parse_cookies(req){
if(req.headers.cookie != null){
var result = req.headers.cookie.match(new RegExp('m:[^=]*=[^; ]*', 'ig'));
if(result != null){
var promises = [];
for(var i = 0; i < result.length; i++){
var result1 = result[i].split('=');
promises.push(getFromRd(req, result1));
}
return Promise.all(promises)
.then(() => {
return next()
})
.catch((e) => {
return next({error: e})
})
}
}
} // parse_cookies
function getFromRd(req, result1) {
req.my_session[result1[0].substr(2)] = result1[1];
// get from redis value
return client.get('sess:'+result1[1], function(err, reply) {
if (err) {
throw Error(' failed to find ' + 'sess:' + result1[1])
}
// reply is null when the key is missing
console.log(reply);
let li = i;
req.my_session[result1[0].substr(2)] = reply;
console.log('li = ' + li);
console.log('result1.lenght= ' + result.length);
return {success:true}
});
}