My goal is to insert the values gotten from a redis hash. I am using the redis package for node js.
My code is the following:
getFromHash(ids) {
const resultArray = [];
ids.forEach((id) => {
common.redisMaster.hget('mykey', id, (err, res) => {
resultArray.push(res);
});
});
console.log(resultArray);
},
The array logged at the end of the function is empty and res is not empty. What could i do to fill this array please ?
You need to use some control flow, either the async library or Promises (as described in reds docs)
Put your console.log inside the callback when the results return from the redis call. Then you will see more print out. Use one of the control flow patterns for your .forEach as well, as that is currently synchronous.
If you modify your code to something like this, it will work nicely:
var getFromHash = function getFromHash(ids) {
const resultArray = [];
ids.forEach((id) => {
common.redisMaster.hget('mykey', id, (err, res) => {
resultArray.push(res);
if (resultArray.length === ids.length) {
// All done.
console.log('getFromHash complete: ', resultArray);
}
});
});
};
In your original code you're printing the result array before any of the hget calls have returned.
Another approach will be to create an array of promises and then do a Promise.all on it.
You'll see this kind of behavior a lot with Node, remember it uses asynchronous calls for almost all i/o. When you're coming from a language where most function calls are synchronous you get tripped up by this kind of problem a lot!
