Here is the Code and where i am sending request to fetching the data and first time it is loading fast and when i am coming back from anuyother page then this page is taking too much time that too when i am using Device.BeginInvokeOnMainThread() within Task.Run().
==============================================================================
public Home()
{
if (HomeModel.GetInstance().GetHomeDataPopulate())
{
FireContentPageInitialized();
}
else
{
CallRequest();
}
}
private async void CallRequest()
{
await Task.Run(async () =>
{
await Task.Delay(3000);
SetBannerData();
SetBrandsData();
SetHotDealsData();
SetNewlyAddedData();
SetRecentlyViewed();
SetRecentlyPurchased();
});
}
//Sending Requests to fetching data in subscribed events...
private void SetBannerData()
{
ModelController.OnGetHomeBannerDataSuccess += ModelController_OnGetHomeBannerDataSuccess;
ModelController.OnGetHomeBannerDataFailure += ModelController_OnGetHomeBannerDataFailure;
ModelController.FetchBannerData();
}
//Fetching Data and binding with UI Itemsource...
private void ModelController_OnGetHomeBannerDataSuccess(object sender, CustomEventArgs eventArgs)
{
stackBanner.ItemsSource = null;
stackBanner.ItemsSource = HomeModel.GetInstance().GetHomeBanners();
}
==============================================================================
This is my Code..and i added comment line where i am binding UI. I can't add lots of code here because it's too lengthy so i have added only one method which is binding UI and other methods are also doing the same.
You are trying to update view by another thread. To update view created by main thread from another thread you must do something like this. Example pseudo code (I don't know your methods).
await Task.Run(() => {
try
{
Device.BeginInvokeOnMainThread(() =>
{
SetBannerData();
SetBrandsData();
SetHotDealsData();
SetNewlyAddedData();
SetRecentlyViewed();
SetRecentlyPurchased();
}
}
catch (Exception ex)
{
}
Related
This issue is driving me nuts :)
Assuming that I have a simple async Task:
async Task AddPoints()
{
await usersDbReference.Child(currentUser).Child("Score").SetValueAsync(newScore).ContinueWith(task =>
{
if(task.IsFaulted || task.IsCanceled)
{
Debug.Log("Couldn't complete task");
}
});
}
What is the simplest way to add the timeout, for example 10 seconds, after which I will show pop up to the user to check his/her internet connection?
Thank you in advance!
EDIT:
I tried below code but it makes the unity crash:
int timeout = 1000;
var task = SomeOperationAsync();
if (await Task.WhenAny(task, Task.Delay(timeout)) == task) {
// task completed within timeout
} else {
// timeout logic
}
I'm using Unity (api compatibility level .Net Standard 2.0, I assume that crash is because of this?)
What I want to achieve:
In case the user doesn't have the internet connection I want to either timeout the task and cancel it or just cancel it after finding out there is no internet connection.
EDIT:
I modified the code. So I have a simple task with cancel token:
async Task CheckTask(CancellationToken csToken)
{
string firstChild = "user";
string secondChild = "testuser";
await FirebaseDatabase.DefaultInstance.RootReference.Child(firstChild).Child(secondChild).GetValueAsync().ContinueWith(task =>
{
if(task.IsFaulted || task.IsCanceled)
{
Debug.Log("Task was canceled");
}
});
}
Then I'm calling it from async void:
public async void FirebaseLogin()
{
bool taskDidntComplete = false;
Debug.Log("Started task");
CancellationTokenSource cs = new CancellationTokenSource();
try
{
var loginTask = CheckTask(cs.Token);
if(loginTask.IsCanceled)
{
Debug.Log("Canceled");
}
if (await Task.WhenAny(loginTask, Task.Delay(10000)) == loginTask)
{
taskDidntComplete = false;
}
else
{
taskDidntComplete = true;
Debug.Log(taskDidntComplete);
cs.Cancel();
throw new TimeoutException();
}
}
catch (Exception e)
{
Debug.Log(e);
}
finally
{
}
}
And while everything works fine and it shows the exception, it doesn't cancel the task. Would be very grateful if someone could tell me what I'm doing wrong.
EDIT2: Works perfect in Unity, doesnt work on Android... Anyone can help? I'm desperate now haha
public async void FirebaseLogin()
{
Debug.Log("Started task");
CancellationTokenSource cs = new CancellationTokenSource();
try
{
var loginTask = CheckTask(cs.Token);
if(loginTask.IsCanceled)
{
Debug.Log("Canceled");
netTestCheck.text = "Canceled";
}
if (await Task.WhenAny(loginTask, Task.Delay(10000)) == loginTask)
{
//netTestCheck.text = "Completed";
}
else
{
netTestCheck.text = "Failed";
cs.Cancel(false);
//throw new TimeoutException();
}
cs.Token.ThrowIfCancellationRequested();
}
catch (Exception e)
{
netTestCheck.text = "Failed2";
Debug.Log(e);
}
finally
{
}
It would help if you could share the exception or stack trace of the crash (integrating Crashlytics could help if you're already in the Firebase ecosystem).
Although I can't spy anything that looks particularly bad in your sample code, if the actual Task fails for whatever reason (say you turn on airplane mode to test, and a suitable exception is raised before your timeout) an exception will get raised there that you aren't handling.
I'd suggest putting a try/catch around your block like:
try {
int timeout = 1000;
var task = SomeOperationAsync();
if (await Task.WhenAny(task, Task.Delay(timeout)) == task) {
// task completed within timeout
} else {
// timeout logic
}
} catch (Exception e) {
Debug.LogError($"{e} occurred!");
}
It's likely to be a DatabaseException, but I'd check first before you get more specific than Exception.
Let me know if that helps!
--Patrick
It unfortunately won't work on Android because app will keep on calling to Firebase. Fortunately found the way around :D
I have xamarin.forms app contains a listview which will load values from Rest API.Which is working fine.I have button just above the listview.When I click on the button, the listview API call will be placed again and the listview should update. But stuck at this update part.I am not using MVVM pattern.The listview listing portion is an async Task.I am calling the async task again when the button click, but App gets crash. Is it due to calling the async task again from button click? Any help is appreciated.
Here is My code.
namespace app
{
public partial class List : ContentPage
{
PendingWeekRange pendingWeekRange = new PendingWeekRange();
public TimeSheetList()
{
InitializeComponent();
Task.Run(async () =>
{
await LoadScreenItems();
});
}
async Task LoadScreenItems()
{
await Task.Run(async () => {
try
{
// Doing some stuff
await loadTimeSheetList();
}
catch (Exception)
{
}
});
}
async Task loadTimeSheetList()
{
await Task.Run(() => { + string postdataForPendingList = "{\"date\":\"" + "1" + "\"}";
APICall callForAPICallResult = new APICall("/API/ListMobile/ListForApproval", postdataForList, loadingIndicator);
try
{
List<ListData> resultObjForPendingTimeSheetList = callForAPICallResult<List<ListData>>();
if (resultObjForPendingTimeSheetList != null)
{
TimesheetList.ItemsSource = resultObjForPendingTimeSheetList;
screenStackLayout.VerticalOptions = LayoutOptions.FillAndExpand;
TimesheetList.IsVisible = true;
}
else
{
}
}
catch (Exception)
{
}
});
}
async void Button_Tapped(object sender, EventArgs e)
{
try
{
// Calling my listview again. After calling app gets crash
Task.Run(async () => await loadTimeSheetList());
}
catch (Exception ex) { }
}
}
}
A few things before getting to the problem. You've got async/await all wrong, go though Async Programming
Task.Run runs the passed action on a different thread, if you make changes to UI elements on this thread, your app will definitely(take my word) crash.
If you want to make async call at page launch, make use of OnAppearing method (if you only want to call once, maintain a flag)
Do not change the ItemsSource of a list view frequently, just clear and add items to it.
namespace app
{
public partial class List : ContentPage
{
PendingWeekRange pendingWeekRange = new PendingWeekRange();
private ObservableCollection<ListData> TimesheetObservableCollection = new ObservableCollection<ListData>();
public TimeSheetList()
{
InitializeComponent();
TimesheetList.ItemsSource = TimesheetObservableCollection;
}
protected override async OnAppearing()
{
// flag for first launch?
await LoadScreenItems();
}
async Task LoadScreenItems()
{
try
{
// Doing some stuff
TimesheetObservableCollection.Clear();
TimesheetObservableCollection.AddRange(await GetTimeSheetList());
}
catch (Exception)
{
//handle exception
}
}
async Task<List<ListData>> GetTimeSheetList()
{
string postdataForPendingList = "{\"date\":\"" + "1" + "\"}";
APICall callForAPICallResult = new APICall("/API/ListMobile/ListForApproval", postdataForList, loadingIndicator);
try
{
return callForAPICallResult<List<ListData>>();
}
catch (Exception)
{
// handle exception
}
}
async void Button_Tapped(object sender, EventArgs e)
{
try
{
// Calling my listview again. After calling app gets crash
TimesheetObservableCollection.Clear();
TimesheetObservableCollection.AddRange(await GetTimeSheetList());
}
catch (Exception ex) { }
}
}
}
#Androdevil,
Update your loadTimeSheetList with this,
async Task loadTimeSheetList()
{
try
{
// I am calling my API for Listview here.
List<TimeSheetListData> resultObjForPendingTimeSheetList = await callForPendingTimeSheetList.APICallResult<List<TimeSheetListData>>();
if (resultObjForPendingTimeSheetList != null)
{
TimesheetList.ItemsSource = resultObjForPendingTimeSheetList;
screenStackLayout.VerticalOptions = LayoutOptions.FillAndExpand;
TimesheetList.IsVisible = true;
}
else
{
}
}
catch (Exception)
{
}
}
Im facing a potential chase error. Im using javafx TableView to display my data, and I'm periodically receiving an update request externally which calls my update function. I also have some listeners which does stuff such as handle mousedrag events etc. What i want to do is to do something like this:
private void handleEvent(){
TableView.setRowFactory(new Callback<TableView<MyModel>, TableRow<MyModel>>(){
public TableRow<MyModel> call(TableView<MyModel> p) {
final TableRow row = new TableRow();
row.setOnDragDetected(new EventHandler<MouseEvent>(){
public void handle(){
//implement some kind of lock to prevent receiving data update
}
}
row.setOnMouseDragExited(new EventHandler<MouseDragEvent>(){
//release lock to accept update
}
}
}
//this method is being called externally periodically
public void updateModel(MyModel model){
//this won't work because it will skip entirely if it's locked,
//I want it to instead run later when lock is released
if (!locked){
this.model = model;
}
}
I did a quick workaround by using a Boolean to lock and unlock as shown in updateModel Method, problem with that is it will lose some updated data because it's skipped entirely.. instead, I want it to run later when lock is released.. how can I implement this kind of lock mechanism and run later feature?
Edit: why I suspect this is because my listeners are manipulating and getting table data.. while the data is constantly updated, I'm not sure if this is causing my table to break.
Just write some logic that collects everything you tried to do in a locked state and executes it on unlocking.
The following code assumes you're using Platform.runLater or similar code that makes the update run on the application thread.
public class UpdateSynchronizer {
private final List<Runnable> pendingUpdates = new ArrayList<>();
private boolean locked = false;
public void lock() {
if (locked) {
throw new IllegalStateException("double lock");
} else {
locked = true;
}
}
public void runUpdate(Runnable updater) {
if (updater == null) {
throw new IllegalArgumentException();
}
if (locked) {
pendingUpdates.add(updater);
} else {
updater.run();
}
}
public void unlock() {
for (Runnable r : pendingUpdates) {
try {
r.run();
} catch(Exception ex) {
ex.printStackTrace(); // print but ignore
}
}
pendingUpdates.clear();
locked = false;
}
}
If the last update always overwrites all the data from previous updates, simply keeping a single Runnable instead of a list of them would be more performant.
private final UpdateSynchronizer synchronizer = new UpdateSynchronizer();
// why did all the keywords start with uppercase letters (compile time error)
private void handleEvent(){
TableView.setRowFactory(new Callback<TableView<myModel>, TableRow<myModel>>(){
public TableRow<myModel> call(TableView<myModel> p) {
final TableRow row = new TableRow();
row.setOnDragDetected(new EventHandler<MouseEvent>(){
public void handle(){
synchronizer.lock();
//implement some kind of lock to prevent receiving data update
}
}
row.setOnMouseDragExited(new EventHandler<MouseDragEvent>(){
//release lock to accept update
synchronizer.unlock();
}
}
}
//this method is being called externally periodically
public void updateModel(myModel model){
synchronizer.runUpdate(() -> {
// this is just an assignment and won't have any side effects
// updates to the scene may only happen, if the model is accessed in some event handler or animation
this.model = model;
});
}
I have a phone application. When a screen displays I start a timer like this:
base.OnAppearing();
{
timerRunning = true;
Device.BeginInvokeOnMainThread(() => showGridTime(5));
}
async void showGridTime(int time)
{
while (timerRunning)
{
var tokenSource = new CancellationTokenSource();
await Task.Delay(time, tokenSource.Token);
detailGrid.IsVisible = true;
}
}
The code seems to work but there is a warning message in the IDE saying that an async method cannot return null.
Given this code can someone help and give me advice on what I should return and if I am going about this in the correct way?
Just return a task:
async Task ShowGridTimeAsync(int time)
{
while (timerRunning)
{
var tokenSource = new CancellationTokenSource();
await Task.Delay(time, tokenSource.Token);
detailGrid.IsVisible = true;
}
}
This is necessary to have the caller of this method know when it is completed and act accordingly.
It is not recommended to create async void methods unless you're creating an event or forced to do that in order to meet an interface signature.
I have a Silverlight project which takes some encrypted string thru its Service Reference: DataService (service which is done in an ASP.NET project).
The method from TransactionServices.cs to get the encrypted string is:
public void GetEncryptedString(string original)
{
DataService.DataServiceClient dataSvc = WebServiceHelper.Create();
dataSvc.GetEncryptedStringCompleted += new EventHandler<SpendAnalyzer.DataService.GetEncryptedStringCompletedEventArgs>(dataSvc_GetEncryptedStringCompleted);
dataSvc.GetEncryptedStringAsync(original);
}
On completing, put the result in encodedString var (which is initialized with an empty value):
void dataSvc_GetEncryptedStringCompleted(object sender, SpendAnalyzer.DataService.GetEncryptedStringCompletedEventArgs e)
{
if (e.Error == null)
{
try
{
if (e.Result == null) return;
this.encodedString = e.Result;
}
catch (Exception ex)
{
Logger.Error("TransactionService.cs: dataSvc_GetEncryptedStringCompleted: {0} - {1}",
ex.Message, ex.StackTrace);
MessageBox.Show(ex.ToString());
}
}
}
Now I want to get the encoded string from my MainPage.xaml like:
TransactionService ts = new TransactionService();
ts.GetEncryptedString(url);
Console.WriteLine(ts.encodedString);
I do not uderstand why ts.encodedString is empty. When I do the debug I see that it actually prints out empty and AFTER that it goes to the void dataSvc_GetEncryptedStringCompleted to take the result and fill it.
Can you point me what I've done wrong? Is there a way to wait for the encodedString to be fetched and only after that to continue?
Thanks a lot.
When you call the ts.GetEncryptedString(url); you just started async operation. And therefor the value you are accessing is will be set only in the callback method.
But you access it before the value is modified by the callback.
The solution which I am using will looks similar to folowing:
Redefine the GetEncryptedString method signature.
public void GetEncryptedString(string original, Action callback)
{
DataService.DataServiceClient dataSvc = WebServiceHelper.Create();
dataSvc.GetEncryptedStringCompleted += (o,e) =>
{
dataSvc_GetEncryptedStringCompleted(o,e);
callback();
}
dataSvc.GetEncryptedStringAsync(original);
}
Call it like this:
ts.GetEncryptedString(url, OtherLogicDependantOnResult);
where
OtherLogicDependantOnResult is
void OtherLogicDependantOnResult()
{
//... Code
}