feat: toPromise removed. (#6598)

BREAKING CHANGE: `toPromise` has been removed from `Observable`. As a workaround, use `firstValueFrom` and `lastValueFrom` functions, which can be imported from `rxjs`. For example `source$.toPromise()` would be `lastValueFrom(source$)`. In the case that you know your source only has one value, we recommend using `firstValueFrom(source$)`.

api_guard/dist/types/index.d.ts

@@ -436,9 +436,6 @@ export declare class Observable<T> implements Subscribable<T> {
     subscribe(observer?: Partial<Observer<T>>): Subscription;
     subscribe(next: (value: T) => void): Subscription;
     subscribe(next?: ((value: T) => void) | null, error?: ((error: any) => void) | null, complete?: (() => void) | null): Subscription;
-    toPromise(): Promise<T | undefined>;
-    toPromise(PromiseCtor: typeof Promise): Promise<T | undefined>;
-    toPromise(PromiseCtor: PromiseConstructorLike): Promise<T | undefined>;
     static create: (...args: any[]) => any;
 }
 

spec-dtslint/Observable-spec.ts

@@ -126,10 +126,6 @@ describe('pipe', () => {
     const customOperator = () => <T>(a: Observable<T>) => a;
     const o = of('foo').pipe(customOperator()); // $ExpectType Observable<string>
   });
-
-  it('should have proper return type for toPromise', () => {
-    const o = of('foo').toPromise(); // $ExpectType Promise<string | undefined>
-  });
 });
 
 describe('subscribe', () => {

spec/util/isPromise-spec.ts

@@ -8,11 +8,6 @@ describe('isPromise', () => {
     expect(isPromise(o)).to.be.true;
   });
 
-  it('should return true for a Promise that comes from an Observable', () => {
-    const o: any = of(null).toPromise();
-    expect(isPromise(o)).to.be.true;
-  });
-
   it('should NOT return true for any Observable', () => {
     const o: any = of(null);
 

src/internal/Observable.ts

@@ -437,46 +437,6 @@ export class Observable<T> implements Subscribable<T> {
   pipe(...operations: OperatorFunction<any, any>[]): Observable<any> {
     return pipeFromArray(operations)(this);
   }
-
-  /* tslint:disable:max-line-length */
-  /** @deprecated Replaced with {@link firstValueFrom} and {@link lastValueFrom}. Will be removed in v8. Details: https://rxjs.dev/deprecations/to-promise */
-  toPromise(): Promise<T | undefined>;
-  /** @deprecated Replaced with {@link firstValueFrom} and {@link lastValueFrom}. Will be removed in v8. Details: https://rxjs.dev/deprecations/to-promise */
-  toPromise(PromiseCtor: typeof Promise): Promise<T | undefined>;
-  /** @deprecated Replaced with {@link firstValueFrom} and {@link lastValueFrom}. Will be removed in v8. Details: https://rxjs.dev/deprecations/to-promise */
-  toPromise(PromiseCtor: PromiseConstructorLike): Promise<T | undefined>;
-  /* tslint:enable:max-line-length */
-
-  /**
-   * Subscribe to this Observable and get a Promise resolving on
-   * `complete` with the last emission (if any).
-   *
-   * **WARNING**: Only use this with observables you *know* will complete. If the source
-   * observable does not complete, you will end up with a promise that is hung up, and
-   * potentially all of the state of an async function hanging out in memory. To avoid
-   * this situation, look into adding something like {@link timeout}, {@link take},
-   * {@link takeWhile}, or {@link takeUntil} amongst others.
-   *
-   * @method toPromise
-   * @param [promiseCtor] a constructor function used to instantiate
-   * the Promise
-   * @return A Promise that resolves with the last value emit, or
-   * rejects on an error. If there were no emissions, Promise
-   * resolves with undefined.
-   * @deprecated Replaced with {@link firstValueFrom} and {@link lastValueFrom}. Will be removed in v8. Details: https://rxjs.dev/deprecations/to-promise
-   */
-  toPromise(promiseCtor?: PromiseConstructorLike): Promise<T | undefined> {
-    promiseCtor = getPromiseCtor(promiseCtor);
-
-    return new promiseCtor((resolve, reject) => {
-      let value: T | undefined;
-      this.subscribe(
-        (x: T) => (value = x),
-        (err: any) => reject(err),
-        () => resolve(value)
-      );
-    }) as Promise<T | undefined>;
-  }
 }
 
 /**