Trigger a StreamController at ngOnInit()
Taking this example from the doc:
Stream<List<Hero>> heroes;
// ···
void ngOnInit() async {
heroes = _searchTerms.stream
.transform(debounce(Duration(milliseconds: 300)))
.distinct()
.transform(switchMap((term) => term.isEmpty
? Stream<List<Hero>>.fromIterable([<Hero>])
: _heroSearchService.search(term).asStream()))
.handleError((e) {
print(e); // for demo purposes only
});
}
Say I want to "trigger" the stream at ngOnInit().
After some tests, I find this can be done by calling void search(String term) => _searchTerms.add(term); just after this:
await Future.delayed(Duration(milliseconds: 1));
Seems that the _searchTerms call inside ngOnInit() is not await.
Could anyone explain why this works that way, or what I am doing wrong?
dart angular-dart dart-html
add a comment |
Taking this example from the doc:
Stream<List<Hero>> heroes;
// ···
void ngOnInit() async {
heroes = _searchTerms.stream
.transform(debounce(Duration(milliseconds: 300)))
.distinct()
.transform(switchMap((term) => term.isEmpty
? Stream<List<Hero>>.fromIterable([<Hero>])
: _heroSearchService.search(term).asStream()))
.handleError((e) {
print(e); // for demo purposes only
});
}
Say I want to "trigger" the stream at ngOnInit().
After some tests, I find this can be done by calling void search(String term) => _searchTerms.add(term); just after this:
await Future.delayed(Duration(milliseconds: 1));
Seems that the _searchTerms call inside ngOnInit() is not await.
Could anyone explain why this works that way, or what I am doing wrong?
dart angular-dart dart-html
add a comment |
Taking this example from the doc:
Stream<List<Hero>> heroes;
// ···
void ngOnInit() async {
heroes = _searchTerms.stream
.transform(debounce(Duration(milliseconds: 300)))
.distinct()
.transform(switchMap((term) => term.isEmpty
? Stream<List<Hero>>.fromIterable([<Hero>])
: _heroSearchService.search(term).asStream()))
.handleError((e) {
print(e); // for demo purposes only
});
}
Say I want to "trigger" the stream at ngOnInit().
After some tests, I find this can be done by calling void search(String term) => _searchTerms.add(term); just after this:
await Future.delayed(Duration(milliseconds: 1));
Seems that the _searchTerms call inside ngOnInit() is not await.
Could anyone explain why this works that way, or what I am doing wrong?
dart angular-dart dart-html
Taking this example from the doc:
Stream<List<Hero>> heroes;
// ···
void ngOnInit() async {
heroes = _searchTerms.stream
.transform(debounce(Duration(milliseconds: 300)))
.distinct()
.transform(switchMap((term) => term.isEmpty
? Stream<List<Hero>>.fromIterable([<Hero>])
: _heroSearchService.search(term).asStream()))
.handleError((e) {
print(e); // for demo purposes only
});
}
Say I want to "trigger" the stream at ngOnInit().
After some tests, I find this can be done by calling void search(String term) => _searchTerms.add(term); just after this:
await Future.delayed(Duration(milliseconds: 1));
Seems that the _searchTerms call inside ngOnInit() is not await.
Could anyone explain why this works that way, or what I am doing wrong?
dart angular-dart dart-html
dart angular-dart dart-html
asked Oct 24 '18 at 19:19
user8773215
add a comment |
add a comment |
1 Answer
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votes
It isn't exactly clear what you are trying to do here, but some background that might help.
Angular lifecycle methods can't be interrupted. They also will not wait for async actions. They are simply callbacks that will be called at the point of the angular lifecycle. Asking angular to wait for you to do work at some unknown point to it is not possible. What if the action never completed? What happens to the rest of the subtree? You would be in some weird state that would invalidate much of the logic and the app.
Instead we use change detection/variables to change the state of the component to handle these async actions. So you could show a progress indicator using a boolean variable until the rpc comes back and then show the results by flipping the variable.
answered Nov 13 '18 at 3:54
Ted SanderTed Sander
1,24127
add a comment |
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1 Answer
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
It isn't exactly clear what you are trying to do here, but some background that might help.
Angular lifecycle methods can't be interrupted. They also will not wait for async actions. They are simply callbacks that will be called at the point of the angular lifecycle. Asking angular to wait for you to do work at some unknown point to it is not possible. What if the action never completed? What happens to the rest of the subtree? You would be in some weird state that would invalidate much of the logic and the app.
Instead we use change detection/variables to change the state of the component to handle these async actions. So you could show a progress indicator using a boolean variable until the rpc comes back and then show the results by flipping the variable.
answered Nov 13 '18 at 3:54
Ted SanderTed Sander
1,24127
add a comment |
It isn't exactly clear what you are trying to do here, but some background that might help.
Angular lifecycle methods can't be interrupted. They also will not wait for async actions. They are simply callbacks that will be called at the point of the angular lifecycle. Asking angular to wait for you to do work at some unknown point to it is not possible. What if the action never completed? What happens to the rest of the subtree? You would be in some weird state that would invalidate much of the logic and the app.
Instead we use change detection/variables to change the state of the component to handle these async actions. So you could show a progress indicator using a boolean variable until the rpc comes back and then show the results by flipping the variable.
answered Nov 13 '18 at 3:54
Ted SanderTed Sander
1,24127
add a comment |
It isn't exactly clear what you are trying to do here, but some background that might help.
Angular lifecycle methods can't be interrupted. They also will not wait for async actions. They are simply callbacks that will be called at the point of the angular lifecycle. Asking angular to wait for you to do work at some unknown point to it is not possible. What if the action never completed? What happens to the rest of the subtree? You would be in some weird state that would invalidate much of the logic and the app.
Instead we use change detection/variables to change the state of the component to handle these async actions. So you could show a progress indicator using a boolean variable until the rpc comes back and then show the results by flipping the variable.
answered Nov 13 '18 at 3:54
Ted SanderTed Sander
1,24127
It isn't exactly clear what you are trying to do here, but some background that might help.
Angular lifecycle methods can't be interrupted. They also will not wait for async actions. They are simply callbacks that will be called at the point of the angular lifecycle. Asking angular to wait for you to do work at some unknown point to it is not possible. What if the action never completed? What happens to the rest of the subtree? You would be in some weird state that would invalidate much of the logic and the app.
Instead we use change detection/variables to change the state of the component to handle these async actions. So you could show a progress indicator using a boolean variable until the rpc comes back and then show the results by flipping the variable.
answered Nov 13 '18 at 3:54
Ted SanderTed Sander
1,24127
answered Nov 13 '18 at 3:54
Ted SanderTed Sander
1,24127
answered Nov 13 '18 at 3:54
Ted SanderTed Sander
1,24127
answered Nov 13 '18 at 3:54
Ted SanderTed Sander
1,24127
1,24127
add a comment |
add a comment |
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