the plugin was auctifera-josed/starprnt.
ionic 3.
pseudo-code
products.forEach(function(product,key)){
starprnt(product);
}
issues: print did not come out even loop finished.
public printAllProduct(products)
{
this.concurrentStart(products);
}
async concurrentStart(products) {
for (const loop_product of products) {
await new Promise( resolve=> setTimeout( resolve, 1000));
this.printProduct(loop_product);
}
}
public function printProduct(product){ pseudoPrintFunction(product); }
Related
I would like to load some Data before I Render my Blazor Application because in depndency to the loaded data I would like to render my app (layout, navbar ...)
Now I want to use the OnInitialised method instead of OnInitialisedAsync and with no async and await keywords.
But now I had a problem to convert the data which I get back from my API.
protected override void OnInitialized()
{
try
{ Console.WriteLine("Test1Mainasync");
LoadCategories();
}
catch (Exception e)
{
jsRuntime.ToastrError(e.Message);
}
}
private void LoadCategories()
{
IEnumerable<CategorieDTO> CategoriesInit1 = new List<CategorieDTO>();
CategoriesInit1 = categorieService.GetAllCategories();
SD.Categories = CategoriesInit1.ToList();
//foreach(var categorie in CategoriesInit){
// SD.Categories.Append(categorie);
//}
Console.WriteLine("Test1Main");
}
Has someone an idea why this converting issues happen?
I think you have this method:
public async Task<IEnumerable<CategorieDTO>> GetAllCategories()
and you should call it this way:
private async Task LoadCategories()
{
IEnumerable<CategorieDTO> CategoriesInit1 = new List<CategorieDTO>();
CategoriesInit1 = await categorieService.GetAllCategories();
and:
protected override async Task OnInitializedAsync()
{
try
{ Console.WriteLine("Test1Mainasync");
await LoadCategories();
}
Has someone an idea why this converting issues happen?
In your code CatagiesInit1 is a Task, it's not a List<CategorieDTO>. You only get the List<CategorieDTO> when the task completes which you have no control over as you don't await the completion of the Task. In all likelyhood, your sync code will run to completion before that happens.
If your CategoryService returns a Task then the code that handles it must be async code. You can't escape from the async world back into the sync world without consequencies. If you want to live in the sync world then all the data pipeline code also needs to be blocking sync code.
If I understand your comments correctly, you want nothing to render until a certain set of conditions are met. If so add some standard Loading... component code to the page if it's page specific or App.razor if it's on initial load, or say MainLayout if it's application wide.
Here's a quick an dirty example:
<Router AppAssembly="#typeof(App).Assembly">
<Found Context="routeData">
#if (Loaded)
{
<RouteView RouteData="#routeData" DefaultLayout="#typeof(MainLayout)" />
<FocusOnNavigate RouteData="#routeData" Selector="h1" />
}
else
{
<div class="m-2 p-5 bg-secondary text-white">
<h3>Loading.....</h3>
</div>
}
</Found>
<NotFound>
<PageTitle>Not found</PageTitle>
<LayoutView Layout="#typeof(MainLayout)">
<p role="alert">Sorry, there's nothing at this address.</p>
</LayoutView>
</NotFound>
</Router>
#code {
private bool Loaded;
protected override async Task OnInitializedAsync()
{
Loaded = false;
// simulate getting the data first
await Task.Delay(5000);
Loaded = true;
}
}
Your call to API endpoint return an awaitable task but not the IEnumerable, So you can not assign awaitable task to IEnumerable so this piece of code wont work
private void LoadCategories()
{
IEnumerable<CategorieDTO> CategoriesInit1 = new List<CategorieDTO>();
CategoriesInit1 = categorieService.GetAllCategories();
}
You should have your LoadCategories function like this
private async Task LoadCategories()
{
IEnumerable<CategorieDTO> CategoriesInit1 = new List<CategorieDTO>();
CategoriesInit1 = await categorieService.GetAllCategories();
}
API calls should be awaitable, else it will stuck your UI
You can use this solution as well
private void LoadCategories()
{
var t = Task.Run(() => categorieService.GetAllCategories()()).GetAwaiter();
t.OnCompleted(() =>
{
CategoriesInit1 = t.GetResult();
// you may need to call statehaschanged as well
StateHasChanged();
});
}
I would like to make a helpfer method which takes a stream from a library (draw in this case) and changes the stream from Stream<UserContent> to Stream<Submission> and also filters the Submissions for duds.
So far I have this code but how do I return the stream now?
Stream<Submission> getSavedPosts({int limit = 20}) async* {
yield await _me!.saved(limit: limit).map((UserContent userContent) async {
try {
Submission sub = await _populateUserContent(userContent);
if (_filterPost(sub)) {
return sub;
}
} catch (err) {
print(err);
}
}); // The type 'Stream<Stream<Future<Submission?>>>' implied by the 'yield' expression must be assignable to 'Stream<Submission>'.
}
you should use asyncMap method on the stream rather than map.
Stream<ClassA> getOldStream() {}
Stream<ClassA> getNewStream() {
return getOldStream().asyncMap((event) async {
return event;
});
}
Note: yield and async* should be used in a generator function; mapping doesn't need a generator function
I'm trying to add some file logging to code invoked by the Workmanager package. The callback has the general structure of the callback routine starting another async task, viz:
Future<void> callbackDispatcher() async {
.
.
.
Workmanager.executeTask((task, inputData) async {
.
.
.
return Future.value(true);
});
.
.
.
}
At the conclusion of whichever of these two routines finishes last, iiuc, I need to do:
iosink.close();
await iosink.done;
before I can exit/return.
As dart doesn't have destructors, I'm not sure how best to accomplish this. I've written the following which, while it seems to work, is rather fragile and somewhat hokey:
class LogWriter2 {
static final File _callbackLogFile = getLocalFile( "callbackLog.out" );
static IOSink _writer;
static int _instanceCount = 0;
LogWriter2._privateConstructor() {
//_writer = _callbackLogFile.openWrite(mode: FileMode.append);
}
static final LogWriter2 _instance = LogWriter2._privateConstructor();
factory LogWriter2() {
if (_instanceCount <= 0) {
debugPrint("${dt.now} constr: opening writer...");
_writer = _callbackLogFile.openWrite(mode: FileMode.append);
}
_instanceCount++;
debugPrint("${dt.now} constr: instanceCount++ now $_instanceCount");
return _instance;
}
writeln(String string) {
var dtn = dt.now;
_writer.writeln("${dtn} $string");
debugPrint("${dtn} lw2.writeln: $string");
}
close() async {
_instanceCount--;
debugPrint("${dt.now} close: instanceCount-- now $_instanceCount");
if (_instanceCount <= 0) {
debugPrint("${dt.now} close: closing writer...");
await _writer.flush(); // close() does not guarantee flush!
_writer.close();
await _writer.done;
debugPrint("${dt.now} close: close complete");
}
}
}
// nb. Don't use this code as-is as it has a race condition that is fixed
// with a mutex (omitted here). Message me if you need a working version.
Can someone suggest a better way of achieving this?
I am switching from async tasks to rxjava2 and have some issues with my code tests.
I have a room table of elements that have a certain monetary amount. On a usercontrol that is called DisplayCurrentBudget, a sum of all amounts should be displayed. This number must refresh everytime a new element is inserted. I tackled the requirement in two ways, but both produce the same result: My code does not care if the database is updated, it only updates when the fragment is recreated (onCreateView).
My first attempt was this:
//RxJava2 Test
Observable<ItemS> ItemObservable = Observable.create( emitter -> {
try {
List<ItemS> movies = oStandardModel.getItemsVanilla();
for (ItemS movie : movies) {
emitter.onNext(movie);
}
emitter.onComplete();
} catch (Exception e) {
emitter.onError(e);
}
});
DisposableObserver<ItemS> disposable = ItemObservable.
subscribeOn(Schedulers.io()).
observeOn(AndroidSchedulers.mainThread()).
subscribeWith(new DisposableObserver<ItemS>() {
public List<ItemS> BadFeelingAboutThis = new ArrayList<ItemS>();
#Override
public void onNext(ItemS movie) {
// Access your Movie object here
BadFeelingAboutThis.add(movie);
}
#Override
public void onError(Throwable e) {
// Show the user that an error has occurred
}
#Override
public void onComplete() {
// Show the user that the operation is complete
oBinding.DisplayCurrentBudget.setText(Manager.GetBigSum(BadFeelingAboutThis).toString());
}
});
I already was uncomfortable with that code. My second attempt produces the exact same result:
Observable<BigDecimal> ItemObservable2 = Observable.create( emitter -> {
try {
BigDecimal mySum = oStandardModel.getWholeBudget();
emitter.onNext(mySum);
emitter.onComplete();
} catch (Exception e) {
emitter.onError(e);
}
});
DisposableObserver<BigDecimal> disposable = ItemObservable2.
subscribeOn(Schedulers.io()).
observeOn(AndroidSchedulers.mainThread()).
subscribeWith(new DisposableObserver<BigDecimal>() {
#Override
public void onNext(BigDecimal sum) {
// Access your Movie object here
oBinding.DisplayCurrentBudget.setText(sum.toString());
}
#Override
public void onError(Throwable e) {
// Show the user that an error has occurred
}
#Override
public void onComplete() {
// Show the user that the operation is complete
}
});
Any obvious issues with my code?
Thanks for reading, much appreciate it!
Edit:
I was asked what Manager.GetBigSum does, it actually does not do much. It only adds BigDecimal-Values of an Item list.
public static BigDecimal GetBigSum(List<ItemS> ListP){
List<BigDecimal> bigDList = ListP.stream().map(ItemS::get_dAmount).collect(Collectors.toList());
return bigDList.stream()
.reduce(BigDecimal.ZERO, BigDecimal::add);
}
Further, I simplified the query. But it still does not care about DB updates, only about fragment recreation:
Single.fromCallable(() -> oStandardModel.getItemsVanilla())
.map(Manager::GetBigSum)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(
e -> oBinding.DisplayCurrentBudget.setText(e.toString())
);
Your rx logic has no error. That should be internal error in your getWholeBudget.
But why you write rx so complex?
For your case, you can just write:
Single.fromCallable(() -> oStandardModel.getItemsVanilla())
.map(Manager::GetBigSum)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(
e -> oBinding.DisplayCurrentBudget.setText(sum.toString()),
e -> log.error(e));
I solved it this way:
oStandardModel.getItemJointCatLive().observe(this, new Observer<List<ItemJointCat>>() {
#Override
public void onChanged(#Nullable final List<ItemJointCat> oItemSP) {
Single.fromCallable(() -> oStandardModel.getWholeBudget())
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(
e -> oBinding.DisplayCurrentBudget.setText(e.toString())
);
}
});
My mistake was that I assumed RXjava2 does not need an onchanged event...now i just use onchanged event of livedata observer to trigger a simple rxjava2 query.
Do you think there is anything wrong with that approach?
The accelerometer is activated (if I set ReadingChanged it works).
Why the shaking event isn't handled?
namespace AppExample
{
public sealed partial class MainPage : Page
{
private Accelerometer accel;
public MainPage()
{
this.InitializeComponent();
this.NavigationCacheMode = NavigationCacheMode.Required;
accel = Accelerometer.GetDefault();
//accel.ReadingChanged += accel_ReadingChanged;
accel.Shaken += accel_Shaken;
}
void accel_Shaken(Accelerometer sender, AccelerometerShakenEventArgs args)
{
Debug.WriteLine("shaken");
}
}
}
If you mind, there is helper librairy called ShakeGestures to handle shake gestures for windows phone 8. check this question
If you're running Windows Phone 8 , Shaken event won't trigger and does not raise any errors according to MSDN page.
Otherwise it seems like a weird bug to me , I couldn't find any information about it.
You can call the Dispatcher in order to show the result on the main thread.
namespace AppExample
{
public sealed partial class MainPage : Page
{
Accelerometer accel;
public MainPage()
{
this.InitializeComponent();
accel = Accelerometer.GetDefault();
accel.ReadingChanged += accel_ReadingChanged;
accel.Shaken += accel_Shaken;
}
await this.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
LabelTest.Text = "Shaken!! " + args.Reading.AccelerationX.ToString();
});
async private void accel_Shaken(object sender, AccelerometerShakenEventArgs e)
{
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
_shakeCount++;
ScenarioOutputText.Text = _shakeCount.ToString();
});
}
}
}