Angular - Convert a Observable<number> to a number

问题

I'm using ngrx store to record state, my state currently holds my list of accounts and the current page (for paging).

On my list of accounts component i call the store to get the current page and pass that to a service (web api) to get the list of accounts.

this.currentPage$ = this.store.select(getCurrentPage);

My angular service is expecting a variable (currentPage) but as a type of number, the store select returns an Observable.

getListOfCustomer(currentPage: number): Observable<ListDto<CustomerList>> {}

My variable this.currentPage$ is currently a type of Observable<number>

How can i convert an Observable<number> to a number to pass it to my service?

回答1:

subscribe to get result as number:

currentPageSub :Subscription;
...
this.currentPageSub = this.store.select(getCurrentPage).subscribe(
 (page: number) => {
     this.currentPage$=page;
 }
);

回答2:

You can create an async function and convert the observable to a promise and await it

async method(){
    var pageNr = await this.currentPage$.toPromise();
    this.getListOfCustomer(pageNr);
}

来源：https://stackoverflow.com/questions/47013653/angular-convert-a-observablenumber-to-a-number