106 lines
3.4 KiB
JavaScript
106 lines
3.4 KiB
JavaScript
import { OuterSubscriber } from '../OuterSubscriber';
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import { subscribeToResult } from '../util/subscribeToResult';
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/**
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* Catches errors on the observable to be handled by returning a new observable or throwing an error.
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*
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* <img src="./img/catch.png" width="100%">
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*
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* @example <caption>Continues with a different Observable when there's an error</caption>
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*
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* Observable.of(1, 2, 3, 4, 5)
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* .map(n => {
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* if (n == 4) {
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* throw 'four!';
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* }
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* return n;
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* })
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* .catch(err => Observable.of('I', 'II', 'III', 'IV', 'V'))
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* .subscribe(x => console.log(x));
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* // 1, 2, 3, I, II, III, IV, V
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*
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* @example <caption>Retries the caught source Observable again in case of error, similar to retry() operator</caption>
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*
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* Observable.of(1, 2, 3, 4, 5)
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* .map(n => {
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* if (n === 4) {
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* throw 'four!';
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* }
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* return n;
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* })
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* .catch((err, caught) => caught)
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* .take(30)
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* .subscribe(x => console.log(x));
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* // 1, 2, 3, 1, 2, 3, ...
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*
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* @example <caption>Throws a new error when the source Observable throws an error</caption>
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*
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* Observable.of(1, 2, 3, 4, 5)
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* .map(n => {
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* if (n == 4) {
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* throw 'four!';
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* }
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* return n;
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* })
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* .catch(err => {
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* throw 'error in source. Details: ' + err;
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* })
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* .subscribe(
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* x => console.log(x),
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* err => console.log(err)
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* );
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* // 1, 2, 3, error in source. Details: four!
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*
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* @param {function} selector a function that takes as arguments `err`, which is the error, and `caught`, which
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* is the source observable, in case you'd like to "retry" that observable by returning it again. Whatever observable
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* is returned by the `selector` will be used to continue the observable chain.
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* @return {Observable} An observable that originates from either the source or the observable returned by the
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* catch `selector` function.
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* @name catchError
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*/
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export function catchError(selector) {
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return function catchErrorOperatorFunction(source) {
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const operator = new CatchOperator(selector);
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const caught = source.lift(operator);
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return (operator.caught = caught);
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};
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}
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class CatchOperator {
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constructor(selector) {
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this.selector = selector;
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}
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call(subscriber, source) {
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return source.subscribe(new CatchSubscriber(subscriber, this.selector, this.caught));
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}
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}
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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class CatchSubscriber extends OuterSubscriber {
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constructor(destination, selector, caught) {
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super(destination);
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this.selector = selector;
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this.caught = caught;
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}
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// NOTE: overriding `error` instead of `_error` because we don't want
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// to have this flag this subscriber as `isStopped`. We can mimic the
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// behavior of the RetrySubscriber (from the `retry` operator), where
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// we unsubscribe from our source chain, reset our Subscriber flags,
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// then subscribe to the selector result.
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error(err) {
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if (!this.isStopped) {
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let result;
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try {
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result = this.selector(err, this.caught);
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}
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catch (err2) {
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super.error(err2);
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return;
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}
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this._unsubscribeAndRecycle();
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this.add(subscribeToResult(this, result));
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}
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}
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}
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//# sourceMappingURL=catchError.js.map
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