At the moment I try to build a data import in Angular. All works fine, but my Backend only allows arround 70 requests. So it runs into an error. My thinking is to put a timeout in angular for Loop with post request. Is this right way to handle this problem? And if yes, how to do this? Can`t find any solution. This is my request at the moment:
for( let x of this.data ){
this.http.post(url,x,{ headers: (reqHeader)}).toPromise().then((data: any) => { console.warn(this.data) })
}
Maybe rate limiting is what you are looking for?
... Then we'll chain it with bufferTime and concatMap. The concatMap operator is where we force the 1000ms delay:
const startTime = (new Date()).getTime();
const source = Observable.range(1, 25)
.concatMap(val => Observable.of(val).delay(75));
source.bufferTime(1000, null, 5)
.concatMap(buffer => Observable.of(buffer).delay(1000))
.timestamp()
.map(obj => {
obj.timestamp = obj.timestamp - startTime;
return obj;
})
.subscribe(obj => console.log(obj));
s what I need, but cant figure out how to use with my code. Have to put it into for loop? How to import Observable.range? Shows me not exists. Thanks a lot.Not sure what you exactly mean by Backend only allows arround 70 requests. But if you wish to control the number of parallel requests at a time, you could use RxJS from, bufferCount and forkJoin functions with concatMap operator.
Try to avoid toPromise(). It is an easier way to switch back to a familiar Promise paradigm, but it's being deprecated in RxJS 7 and will be gone in RxJS 8. Instead try to subscribe to the observables.
For controlled parallel requests, try the following
const reqs = this.data.map(item => this.http.post(url, item, { headers: (reqHeader) }))
from(reqs).pipe(
bufferCount(6), // <-- adjust number of parallel requests here
concatMap(buffer => forkJoin(buffer))
).subscribe(
res => console.warn(res),
err => console.log(err),
() => console.log('complete')
);
You could forgo the bufferCount and instead switch to each request individually and use an explicit delay. Try the following
from(this.data).pipe(
concatMap(item => this.http.post(url, item, { headers: (reqHeader) }).pipe(
delay(3000) // <-- wait 3 seconds b/n each request
))
).subscribe(
res => { },
err => { }
);
You could introduce a variable (eg. count) and use the map operator to return both the count and the response.
Try the following
someFunc() {
let count = 0;
from(this.data).pipe(
concatMap(item => this.http.post(url, item, { headers: (reqHeader) }).pipe(
map(res => {
count++;
return {
count: count,
response: res
}
}),
delay(3000) // <-- wait 3 seconds b/n each request
))
).subscribe(
res => {
console.log(res.count); // <-- the count of the emission
console.log(res.response); // <-- the response from `this.http.post()`
},
err => { }
);
}
Retry-After header? How long is the wait time?delay operator. Please check if it works for you.