我有一个要解析的项目列表,但其中一个项目的解析可能会失败。
捕获错误但继续执行序列的"Rx-Way“是什么
代码示例:
var observable = Rx.Observable.from([0,1,2,3,4,5])
.map(
function(value){
if(value == 3){
throw new Error("Value cannot be 3");
}
return value;
});
observable.subscribe(
function(value){
console.log("onNext " + value);
},
function(error){
console.log("Error: " + error.message);
},
function(){
console.log("Completed!");
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/4.0.6/rx.all.js"></script>
我想以一种非Rx的方式:
var items = [0,1,2,3,4,5];
for (var item in items){
try{
if(item == 3){
throw new Error("Value cannot be 3");
}
console.log(item);
}catch(error){
console.log("Error: " + error.message);
}
}
提前感谢
发布于 2016-07-30 02:58:13
我建议您改用flatMap
(现在rxjs版本5中的mergeMap
),如果您不关心错误,它将允许您折叠错误。实际上,您将创建一个内部可观察对象,如果发生错误,该对象可以被吞并。这种方法的优点是,您可以将操作符链接在一起,如果管道中的任何地方发生错误,它将自动转发到catch块。
const {from, iif, throwError, of, EMPTY} = rxjs;
const {map, flatMap, catchError} = rxjs.operators;
// A helper method to let us create arbitrary operators
const {pipe} = rxjs;
// Create an operator that will catch and squash errors
// This returns a function of the shape of Observable<T> => Observable<R>
const mapAndContinueOnError = pipe(
//This will get skipped if upstream throws an error
map(v => v * 2),
catchError(err => {
console.log("Caught Error, continuing")
//Return an empty Observable which gets collapsed in the output
return EMPTY;
})
)
const observable = from([0, 1, 2, 3, 4, 5]).pipe(
flatMap((value) =>
iif(() => value != 3,
of(value),
throwError(new Error("Value cannot be 3"))
).pipe(mapAndContinueOnError)
)
);
observable.subscribe(
(value) => console.log("onNext " + value), (error) => console.log("Error: " + error.message), () => console.log("Completed!")
);
<script src="https://unpkg.com/rxjs@7.0.0/dist/bundles/rxjs.umd.min.js"></script>
发布于 2017-06-22 22:04:33
您需要切换到一个新的可处理流,如果其中发生错误,将被安全地处理,并保持原始流存活:
Rx.Observable.from([0,1,2,3,4,5])
.switchMap(value => {
// This is the disposable stream!
// Errors can safely occur in here without killing the original stream
return Rx.Observable.of(value)
.map(value => {
if (value === 3) {
throw new Error('Value cannot be 3');
}
return value;
})
.catch(error => {
// You can do some fancy stuff here with errors if you like
// Below we are just returning the error object to the outer stream
return Rx.Observable.of(error);
});
})
.map(value => {
if (value instanceof Error) {
// Maybe do some error handling here
return `Error: ${value.message}`;
}
return value;
})
.subscribe(
(x => console.log('Success', x)),
(x => console.log('Error', x)),
(() => console.log('Complete'))
);
<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/5.4.1/Rx.min.js"></script>
有关此技术的更多信息,请参阅此博客文章:The Quest for Meatballs: Continue RxJS Streams When Errors Occur
发布于 2019-11-01 22:55:04
为了避免你的endlessObservable$
死掉,你可以把你的failingObservable$
放在一个更高阶的映射运算符中(例如switchMap
,concatMap
,exhaustMap
...)并通过使用不返回值的empty()
observable终止内部流来接受错误。
使用RxJS 6:
endlessObservable$
.pipe(
switchMap(() => failingObservable$
.pipe(
catchError((err) => {
console.error(err);
return EMPTY;
})
)
)
);
https://stackoverflow.com/questions/38649652
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