问题描述
错误或没有错误,我想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$ 始终抛出错误。我想忽略最后的错误,仍然将编辑器返回到订阅成功处理程序。
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))
找到文本时输出(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"}
未找到文本时的目标输出(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输出(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 以使其成为订阅成功处理程序。但它仍然没有。有什么想法吗?
解决方法
使用 retryWhen
是不可能的。
重试给定尝试后的 retryWhen
运算符 completes
(在本例中,由 take(3)
和 delay(1000)
指定)。因此,如果在重试期间,您的源 observable checkForText$
没有发出已解决的承诺或非错误值,则由 checkForText$ 和 retryWhen 组成的管道将不会发出任何内容,最终流将完成重试后.
此后无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。
所以,如果你在你的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
);
当没有找到带有 setTimeout 注释的文本时,您的情况将返回以下内容 -
checking for text {innerText: ""}
no text found... retrying
checking for text {innerText: ""}
checking for text {innerText: ""}
checking for text {innerText: ""}
I'm done!
然而,您可以使用 retry
实现此目的,但我不确定仅使用 retry
会如何引入延迟。
editorOpened$
.pipe(
switchMap(editor =>
checkForText$.pipe(
retry(3),catchError(errors => of(editor))
)
)
)
.subscribe(
editor => {
console.log("FINISH CHECKING",editor);
},err => console.log("ERROR ",() => console.log("I'm done!")
);
这将产生:
checking for text {innerText: ""}
checking for text {innerText: ""}
checking for text {innerText: ""}
checking for text {innerText: ""}
FINISH CHECKING {innerText: ""}
I'm done!
,
正如上面的帖子所指出的,它不可能使用 retryWhen。您但是可以使用重试来实现这一点,确保您的源可观察对象处理任何延迟。
editorOpened$
.pipe(
mergeMap(editor =>
checkForText$.pipe(
retry(3),catchError(errors => of(editor))
)
)
)
.subscribe(
editor => console.log("Finish",editor);,err => console.log("Error",_ => console.log("Complete")
);
源可观察
function checkforText(){
return new Promise((resolve,reject) => {
console.log('checking for text',editor)
if (editor.innerText == ""){
setTimeout(_=> reject('No text'),500); // reject after half a second
} else {
resolve(editor)
}
})
}
var checkForText$ = defer(_=> from(checkforText()))