Angular tutorial中提出了一个错误处理程序,该处理程序在发生错误的情况下可以将默认值返回给调用方。
/**
* Handle Http operation that failed.
* Let the app continue.
* @param operation - name of the operation that failed
* @param result - optional value to return as the observable result
*/
private handleError<T> (operation = 'operation', result?: T) {
return (error: any): Observable<T> => {
// TODO: send the error to remote logging infrastructure
console.error(error); // log to console instead
// TODO: better job of transforming error for user consumption
this.log(`${operation} failed: ${error.message}`);
// Let the app keep running by returning an empty result.
return of(result as T);
};
}
现在,我使用async/await进行了网络服务调用:
public async getItemsAsync() {
try {
return await this.http.get<string[]>("/some/url").toPromise();
}
catch (error) {
this.handleError<string[]>('getItemsAsync', []);
}
}
我必须更改什么才能能够从错误处理程序返回默认值?
private handleError<T>(operation = 'operation', result?: T) {
console.log(`${operation} failed: ${error.message}`);
// let the app keep running by returning an empty result.
return result as T;
}
我应该返回
Observable
还是Promise
?我都尝试过,但是没有编译。目前,尚未返回string[]
。我只得到undefined
。
最佳答案
考虑在可观察的级别上处理错误:
async getItemsAsync() {
return await this.http
.get<string[]>("/some/url")
.pipe(catchError(this.handleError<string[]>("getItemsAsync", [])))
.toPromise();
}
您可以使用RxJS中的
catchError
运算符。这将运行您的错误日志记录,并将您指定的值的可观察值返回给handleError
函数。然后,您的toPromise
运算符将可观察到的错误或api响应中的值转换为promise。Stackblitz demo
关于angular - 使用异步/等待时,错误处理程序返回默认值,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58690926/