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[英]How to retry only on certain error emitted by the source observable in RxJs
[英]Retry, then ignore error and get source value rxjs
错误或没有错误,我想在重试后进入订阅成功处理程序。 要进行测试,请注释掉 setTimeout 行。 这将使 checkforText$ 总是抛出错误。 我想忽略最后的错误,仍然将编辑器返回给订阅成功处理程序。
https://codepen.io/Spankid/pen/gOgVZEE
var editor = { innerText: "" }
var editorOpened$ = of(editor) // observe editor object
function checkforText(){
return new Promise((resolve,reject) => {
console.log('checking for text',editor)
if (editor.innerText == ""){
reject('No text');
} else {
resolve(editor)
}
})
}
var checkForText$ = defer( () => from(checkforText())) // observe text on editor object
// comment out this line out to test
setTimeout( _ => { editor.innerText = 'testing' }, 2000)
editorOpened$.pipe(
switchMap(editor =>
checkForText$.pipe(
retryWhen(errors => {
console.log ('no text found... retrying')
return errors.pipe(
delay(1000),
take(3),
)
}),
)
)
).subscribe(editor => {
console.log('FINISH CHECKING', editor)
}, err => console.log('ERROR ',err))
找到文本时的 Output(setTimeout 未注释掉):
checking for text {innerText: ""}
no text found... retrying
checking for text {innerText: ""}
checking for text {innerText: "testing"}
FINISH CHECKING {innerText: "testing"}
找不到文本时目标 output(注释掉 setTimeout):
checking for text {innerText: ""}
no text found... retrying
checking for text {innerText: ""}
checking for text {innerText: ""}
checking for text {innerText: ""}
FINISH CHECKING {innerText: ""}
未找到文本时的实际 output(注释掉 setTimeout):
checking for text {innerText: ""}
no text found... retrying
checking for text {innerText: ""}
checking for text {innerText: ""}
checking for text {innerText: ""}
我尝试在 retryWhen 之后添加 catchError,希望将其变成订阅成功处理程序。 但它仍然没有。 有任何想法吗?
retryWhen
是不可能的。
retryWhen
运算符在重试给定尝试后completes
(在这种情况下,由take(3)
和delay(1000)
指定)。 因此,如果在重试期间,您的可观察源checkForText$
没有发出已解析的 promise 或非错误值,则由 checkForText$ 和 retryWhen 组成的管道不会发出任何内容,最终 stream 将完成后重试。
在那之后没有办法进入成功处理程序,除非您专门让 checkForText$ 在重试期间发出一些非错误值。
因此,如果您在观察者中添加一个完整的回调,如下所示,
editorOpened$.pipe(
switchMap(editor =>
checkForText$.pipe(
retryWhen(errors => {
console.log ('no text found... retrying')
return errors.pipe(
delay(1000),
take(3),
)
}),
)
)
).subscribe(editor => {
console.log('FINISH CHECKING', editor)
},
(err) => console.log('ERROR ',err),
() => console.log('I'm done!') //The complete handler
);
当您没有找到带有 setTimeout 注释的文本时,您的情况将返回以下 -
checking for text {innerText: ""}
no text found... retrying
checking for text {innerText: ""}
checking for text {innerText: ""}
checking for text {innerText: ""}
I'm done!
但是,您可以使用retry
来实现此目的,但我不确定如何仅使用retry
来引入延迟。
editorOpened$
.pipe(
switchMap(editor =>
checkForText$.pipe(
retry(3),
catchError(errors => of(editor))
)
)
)
.subscribe(
editor => {
console.log("FINISH CHECKING", editor);
},
err => console.log("ERROR ", err),
() => console.log("I'm done!")
);
这将产生:
checking for text {innerText: ""}
checking for text {innerText: ""}
checking for text {innerText: ""}
checking for text {innerText: ""}
FINISH CHECKING {innerText: ""}
I'm done!
正如上面的帖子所指出的, retryWhen 是不可能的。 但是,您可以使用 retry 来实现这一点,方法是确保您的源 observable 处理任何延迟。
editorOpened$
.pipe(
mergeMap(editor =>
checkForText$.pipe(
retry(3),
catchError(errors => of(editor))
)
)
)
.subscribe(
editor => console.log("Finish", editor);,
err => console.log("Error", err),
_ => console.log("Complete")
);
源可观察
function checkforText(){
return new Promise((resolve,reject) => {
console.log('checking for text', editor)
if (editor.innerText == ""){
setTimeout(_=> reject('No text'), 500); // reject after half a second
} else {
resolve(editor)
}
})
}
var checkForText$ = defer(_=> from(checkforText()))
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