how to keep calling a backend api until i receive the 200 ok in the response-CodePudding

I am developing an angular project, I need to call a backend api, if it's not return 200, then i need to call this api every 30 seconds, until I get 200 OK.

I am using angular, the format I usually call an backend api is this:

this.productServices.onProductBuy(product_id).subscribe(response => {
    console.log(response)
});

onProductBuy() contains some calling api code, it's just simply a get request

If a HTTP 200 is not received for this onProdcutBuy api, I need to call this api one more time until I get the 200.

CodePudding user response：

This should do the trick:

this.productServices.onProductBuy(product_id).pipe(
  retry({
    delay: 30 * 1000
  } as any)
).subscribe(response => {
  console.log(response)
});

This retry an infinite amount of times and also add a delay of 30 second. The type definition of retry seems to be broken with the version I am using. That's why I had to use as any.

But the source code shows, that retry accepts an object with a delay property:

export interface RetryConfig {
  /**
   * The maximum number of times to retry. If `count` is omitted, `retry` will try to
   * resubscribe on errors infinite number of times.
   */
  count?: number;
  /**
   * The number of milliseconds to delay before retrying, OR a function to
   * return a notifier for delaying. If a function is given, that function should
   * return a notifier that, when it emits will retry the source. If the notifier
   * completes _without_ emitting, the resulting observable will complete without error,
   * if the notifier errors, the error will be pushed to the result.
   */
  delay?: number | ((error: any, retryCount: number) => ObservableInput<any>);
  /**
   * Whether or not to reset the retry counter when the retried subscription
   * emits its first value.
   */
  resetOnSuccess?: boolean;
}

export function retry<T>(count?: number): MonoTypeOperatorFunction<T>;
export function retry<T>(config: RetryConfig): MonoTypeOperatorFunction<T>;

CodePudding user response：

You could use rxjs retry:

this.productServices.onProductBuy(product_id)
  .pipe(retry(2)) // <-- Here
  .subscribe(response => {
    console.log(response)
  });

With the above it will retry twice. If you'd like to retry forever, just don't add a number to it, it will keep retrying until a success is received:

this.productServices.onProductBuy(product_id)
  .pipe(retry()) // <-- Here
  .subscribe(response => {
    console.log(response)
  });

Don't forget to avoid the memory leak trap with subscriptions.