Nestjs Framework: Run parallel task using Async - node.js

Question

I'm struggling right now with "async".
I'm starting with NestJs Framework and i need run a bunch of task on parallel.
Before, using Nodejs + Express only, i have been useing something like this
...
...
.get('/some/path', function(){
async.parallel({
todayBalance: async.apply(function (cb) {
return SomeFunction(params, cb);
}),
currentWeek: async.apply(function (cb) {
return SomeFunction2(params, cb);
}),
...
...
// more tasks
},
function (err, results) {
# some code for logic
# here i get my result and gather data and RETURN
});
});
Nowadays, using NestJs framework, i have got something like this
myservice.ts
This is a service created for doing this.
// Service Definitions
async someFunction(userBusinessId: string): Promise<any> {
// i tried to use same strategy from Async
// but nothing accuring
async.parallel({
todayBalance: async.apply(function (cb) {
return SomeFunction(params, cb);
}),
currentWeek: async.apply(function (cb) {
return SomeFunction2(params, cb);
}),
...
...
// more tasks
},
function (err, results) {
# some code for logic
# here i get my result and gather data and RETURN
# DOESNT RETURN, NEVER EVER GETS HERE
});
}
Any idea what's wrong?
Thanks for your support!

Answer 1

First off I made two basics mistake
1. I Forgot use cb Function
using Nodejs + Express we just made something like this
In this case I use mysql
const SomeFunction= (userBusinessId, cb) => {
cnx.connection.query(`some pretty query`,
cb // <===== use Callback here
);
};
now using Nestjs i tried(badly results) to made something like this. Ignoring cb
const SomeFunction= (userBusinessId, cb) => {
const data = await getManager().query(`some pretty query`);
return data; // <===== WRONG INSTEAD USE cb Function, using like this parallel function will never triggered
};
Instead return single data, we must trigger the cb function overloading with result
Documentation
const SomeFunction= (userBusinessId, cb) => {
...
cb(null, data); // EXECUTE LIKE THIS, this will resume the pipe. null param suppose no error
};
2. Try to return the function service value inside the Async callback
Even if you try to do something like
async list():Promise<any>{
async.parallel({
...
// more tasks
},
function (err, results) {
return data;
});
}
OR
async list():Promise<any>{
const data = await async.parallel({
...
// more tasks
},
function (err, results) {
return data;
});
return data;
}
this funtion with always return undefined. even if you remove the Funtion Type Promise<any>
For avoid this you must return a Promise like
async list():Promise<any>{
return new Promise( (resolver, reject) => {
async.parallel({
...
// more tasks
},
function (err, results) {
if(err)
reject(err);
...
resolver(results);
});
} )
}
Hope this help you too!