I'm experiencing some issues with my eventacllback which I'm charging with multiple (at least 2) parameters. The Child component gets underlined in red, even though the whole project runs and there's no runtime issues with that. It just bugs me the errors listed in Error List window. Plus I've mentioned the Hot Reload complains about it and not working. Below are the details.
VS underlines in red the eventcallbacks
As you can see from the above picture, the callback events with just one parameter are fine, it just complains when multiple are present.
The definition of the callback is like below:
[Parameter] public EventCallback<(int, int, string)> OnRecordLevelMenuItemClick { get; set; }
and there's nothing exceptional the way I'm invoking it:
await OnRecordLevelMenuItemClick.InvokeAsync((buttonId, menuId??0, recordId));
Here's how I'm handling the eventcallback in my Parent component:
private void RowLevelmenuItemClickHandler(int buttonId, int menuId, string recordId)
{
var menuOption = _menuItems.GetValueOrDefault(menuId);
_snackBar?.Add($"Menu clicked. Option: {menuOption}", Severity.Info);
}
As I've previously mentioned, there's no compilation errors and everything works fine. It's just not being able to use the Hot Reload that kills me.
Any ideas will be greatly appreciated.
Related
I'm trying to wrap my head around how to manage controlled and uncontrolled results/failures in Azure Functions triggered by Event Grid events. I'm sure I'm missing some fundamental aspect but I can't really make sense of the available Microsoft documentation.
Using the current Visual Studio 2019 Azure Function templates for Event Grid triggers, we get C# methods that looks similar to this:
[FunctionName("UserCreated")]
public static void UserCreated([EventGridTrigger]EventGridEvent evt, ILogger log)
{
...
}
Q1. What is the proper way of returning statuses and error codes from these methods so that the event can be either retried or passed to the dead letter blob? Lets say I want to return a Status 400 Bad Request because the custom data payload in the event that was passed in wasn't up to speed. I've tried this:
[FunctionName("UserCreated")]
public static async Task<IActionResult> UserCreated([EventGridTrigger]EventGridEvent evt, ILogger log)
{
...
return new BadRequestObjectResult("ouch");
}
... which just results in this error when running the function locally:
Cannot bind parameter '$return' to type IActionResult&. Make sure the parameter Type is supported by the binding.
I don't understand this error and have no idea how to solve it.
Q2. How do we properly catch exceptions and return them in an orderly fashion? Let's say the UserCreated method above requires the passed in event to have a few custom datapoints, and that one of those datapoints are missing. E.g. we have this:
[JsonObject(ItemRequired = Required.Always)]
private class CustomerAndContactIds
{
public int CustomerId { get; set; }
public int ContactId { get; set; }
}
... and when we convert some event data that is missing e.g. the ContactID field, like so:
private static T ExtractCustomPayloadFromEvent<T>(EventGridEvent evt)
{
return JObject.FromObject(evt.Data).ToObject<T>();
}
... we get this in the logs:
System.Private.CoreLib: Exception while executing function: UserCreated. Newtonsoft.Json: Required property 'ContactPersonId' not found in JSON. Path ''.
However, all we get in e.g. Postman is:
Exception while executing function: UserCreated
What's the proper way of making this a bit more legible for consumers that aren't privy to e.g. the Azure log stream or Azure Insights?
To Q1:
Currently version of the EventGridTrigger function doesn't have a specific exception object to handle for its wrapper back a HttpStatusCode value. In other words, any exception in the azure function will force a retry pattern when it is enabled.
As a workaround for this issue, we can use a HttpTrigger function for subscriber handler with the HttpStatusCode return value.
While trying to navigate from one Page to another, I'm getting this "Invalid attribute value Unknown for property BorderThickness." error.
If I step through the code in the debugger everything works fine. If I let the navigation happen on it's own, the code crashes.
Outside of setting BorderThickness to specific (integer) values or using the built-in ThemeResources, these values are not ever tied to bound values that might be null or have an unexpected value.
This code was working fine at one point, but that seems to have come to an end this morning.
I'm still not certain why this is an issue, but I can identify specifically where the error is occurring.
public async void OnLevelUp(object sender, EventArgs e)
{
IsBusy = true;
LevelUpVm.CharacterId = IoC.Game.GetCharacter(SelectedCharacter.Id).Id;
**await IoC.SaveConfigFile();** <<< OFFENDING LINE OF CODE
var rootFrame = Window.Current.Content as Frame;
rootFrame?.Navigate(typeof(LevelUpView), null);
IsBusy = false;
}
If I move the OFFENDING LINE OF CODE after the rootFrame?Navigate line, it works fine.
So, after 5 hours of messing with the code, I've come to a solution - but I'm still not certain why the await call causes the problem.
At first, this exception doesn't really make sense to me. Why shouldn't i be able to duplicate this object multiple times? but thats not the point:
i use a List. Whenever i navigate to a site, it should do this:
(App.Current as App).recent.ForEach(x => container.Children.Add(x));
(container = another StackPanel)
the first time, it works. afterwards, i get the exception displayed in the questiontitle. i already tried using a listbox, but i just got a ArgumentException. I think these exceptions have the same source, but i don't know what i'm doing wrong. please help
thanks
The error is quite clear: A WPF/SL Control can only belong to 1 Parent control at a time.
So you'll either have to remove the Controls from their Parent when you are moving away from a Page or you'll have to Create (possibly Clone) new Controls in this ForEach.
When you navigate to a page, the old instance is not removed instantly, so when you add your controls to the new page, they may still be used in the old page if it's not destroyed, causing the exception.
Try overriding the OnNavigatedFrom(NavigationEventArgs e) and OnNavigatingFrom(NavigatingCancelEventArgs e) methods that are invoked when you leave a page so that you empty your StackPanel.
For example, you could do :
protected override void OnNavigatedFrom(NavigationEventArgs e)
{
base.OnNavigatedFrom(e);
container.Children.Clear();
}
You have to remove the container's children when you navigate from the page. But not if the navigation is due to a suspend. To avoid the children clear when the navigation is due to a suspend it is better to override OnNavigatingFrom instead of OnNavigatedFrom
protected override void OnNavigatingFrom(NavigatingCancelEventArgs e)
{
container.Children.Clear();
base.OnNavigatingFrom(e);
}
I'm not sure but from my hours of debugging, this should be the best description of my problem I can give.
I'm creating a WinRT app, there are two pages- Main Page and Details Page. Inside Main Page constructor, I have initialized a listbox. On click of any of the element of listbox, user is taken to the Details page.
I'm just learning all this and design may not be best but here is what I did.
I took a static variable in MainPage.cs, and set it to point to the element which is clicked by the user. Now in the constructor of the Details page, I used this static variable to set the datacontext of Details Page itself.
What flow I'm expecting is:-
MainPage is created first. Listbox is setup.
User will click on any of the element of listbox. Itemclick event handler runs. It will set the static variable (of Mainpage.cs) to hold the infomation which item is clicked and navigate user to the Details page.
In Details page constructor, I have set the datacontext to point to some information based on the value of static variable mentioned in the previous step.
It works for most of the times, but once in like every 5 times, The Details page constructor throws an exception stating the static variable is not initialized yet. Why is Details page's constructor running when I'm starting the app? and why only sometimes? Do I need to set DataContext of Details Page in some other method instead of constructor?
The code is somewhat complex and too much in terms of domain of the problem so I'm avoiding posting it. But if I'm failing to explain the problem please tell, I'll post it keeping it as related as I can.
CODE:-
This is the method called when an item in listbox is clicked--will take user to the Details page.
private void overviewlistbox_Tapped_1(object sender, TappedRoutedEventArgs e)
{
MatchOverview selectedmatch = (sender as ListBox).SelectedItem as MatchOverview;
matchFullDetails = new ObservableCollection<Match>();
foreach (Match m in UpdateController.matchList)
{
if (m.matchDescription == selectedmatch.matchDesc)
{
matchFullDetails.Add(m);
break;
}
}
if(!(matchFullDetails.Count == 0))
this.Frame.Navigate(typeof(Details));
}
This is the constructor for Main Page:-
public static ObservableCollection<Match> matchFullDetails;
public MainPage()
{
matchFullDetails = new ObservableCollection<Match>();
this.InitializeComponent();
UpdateController update = new UpdateController(); // Creating new object will update the overview_list of UpdateController(static list).
overviewlistbox.ItemsSource = UpdateController.overview_list;
}
And this is the code for constructor of details page, where the exception occurs:-
public static ObservableCollection<Match> matchdetails = new ObservableCollection<Match>();
DispatcherTimer dtm_detailspage = null;
public Details()
{
this.InitializeComponent();
matchdetails = MainPage.matchFullDetails; // matchdetails.Last<>() is take because we only need item which is added latest to the collection.
if (matchdetails.Last<Match>().type == "TEST") // Exception is thrown here--Initialization
// error. When I check MainPage.matchFullDetails,
// no data is shown which means its not yet
// initialized. Also the exception is thrown either at
// the start of the app, or when details page is visited. That too once in 4-5 times, not always.
{
matchdetails.Add(matchdetails.First<Match>() as TestMatch);
}
if (matchdetails.Last<Match>().type == "ODI")
{
matchdetails.Add(matchdetails.Last<Match>() as ODIMatch);
}
if (matchdetails.Last<Match>().type == "T20")
{
matchdetails.Add(matchdetails.Last<Match>() as T20Match);
}
}
Exception Screenshot:-
Call Stack data on bug encounter:-
[Cricket Expert.exe!Cricket_Expert.Details.Details() Line 33 + 0x5 bytes
[External Code]
Cricket Expert.exe!Cricket_Expert.Common.SuspensionManager.RestoreFrameNavigationState(Windows.UI.Xaml.Controls.Frame frame) Line 236 + 0x5 bytes
Cricket Expert.exe!Cricket_Expert.Common.SuspensionManager.RestoreAsyn() Line 124 0x8 bytes
Cricket Expert.exe!Cricket_Expert.App.OnLaunched(Windows.ApplicationModel.Activation.LaunchActivatedEventArgs args) Line 74 + 0x5 bytes
[External Code]
MAJOR UPDATE:
I finally found the flaw. If the Details page is still active, and the app is restarted, the problem occurs.
Is there a solution to this problem??
You can pass information on what needs to be displayed on the Details page through the Navigate call and set the DataContext in OnNavigatedTo override to avoid using static variables. Pages don't get created unless you do it specifically e.g. by navigating to one. They might not be recreated if a page has NavigationCacheMode changed from the default (Disabled) so instances of the page can be reused during navigation calls. Ultimately it's hard to say what's wrong but it seems like something in your code and we couldn't help you if you don't share a sample that reproduces the problem.
*EDIT
One way to debug Details being created before MainPage would be to add this code at the beginning of the Details constructor:
if (MainPage.matchFullDetails == null)
{
System.Diagnostics.Debugger.Break();
}
Then look at the Call Stack panel in Visual Studio to see how it gets constructed.
One way to see if matchFullDetails is ever set to null is to search for its assignment (put a cursor on matchFullDetails in Visual Studio code editor and hit Shift+F12).
Another way would be to make matchFullDetails into a property and test it like this:
private static ObservableCollection<Match> _matchFullDetails;
public static ObservableCollection<Match> matchFullDetails
{
get
{
return _matchFullDetails;
}
set
{
if (value == null)
{
System.Diagnostics.Debugger.Break();
}
_matchFullDetails = value;
}
}
*EDIT 2
You can initialize your static property in a static constructor like this:
public static ObservableCollection<Match> matchFullDetails;
static MainPage()
{
matchFullDetails = new ObservableCollection<Match>();
}
public MainPage()
{
this.InitializeComponent();
UpdateController update = new UpdateController(); // Creating new object will update the overview_list of UpdateController(static list).
overviewlistbox.ItemsSource = UpdateController.overview_list;
}
this will prevent the null reference exception but won't fix your problem overall. When your app gets suspended and resumed - you have to restore the full state and it seems like your matchFullDetails collection would need to be serialized and saved to disk when your app gets suspended. Alternatively you might simply ignore the suspension manager call in App.xaml.cs and always start on home page, though that's not a very good experience and I am not sure if it satisfies app certification.
The problem: I'm crashing when I want to render my incoming data which was retrieved asynchronously.
The app starts and displays some dialog boxes using XAML. Once the user fills in their data and clicks the login button, the XAML class has in instance of a worker class that does the HTTP stuff for me (asynchronously using IXMLHTTPRequest2). When the app has successfully logged in to the web server, my .then() block fires and I make a callback to my main xaml class to do some rendering of the assets.
I am always getting crashes in the delegate though (the main XAML class), which leads me to believe that I cannot use this approach (pure virtual class and callbacks) to update my UI. I think I am inadvertently trying to do something illegal from an incorrect thread which is a byproduct of the async calls.
Is there a better or different way that I should be notifying the main XAML class that it is time for it to update it's UI? I am coming from an iOS world where I could use NotificationCenter.
Now, I saw that Microsoft has it's own Delegate type of thing here: http://msdn.microsoft.com/en-us/library/windows/apps/hh755798.aspx
Do you think that if I used this approach instead of my own callbacks that it would no longer crash?
Let me know if you need more clarification or what not.
Here is the jist of the code:
public interface class ISmileServiceEvents
{
public: // required methods
virtual void UpdateUI(bool isValid) abstract;
};
// In main XAML.cpp which inherits from an ISmileServiceEvents
void buttonClick(...){
_myUser->LoginAndGetAssets(txtEmail->Text, txtPass->Password);
}
void UpdateUI(String^ data) // implements ISmileServiceEvents
{
// This is where I would render my assets if I could.
// Cannot legally do much here. Always crashes.
// Follow the rest of the code to get here.
}
// In MyUser.cpp
void LoginAndGetAssets(String^ email, String^ password){
Uri^ uri = ref new URI(MY_SERVER + "login.json");
String^ inJSON = "some json input data here"; // serialized email and password with other data
// make the HTTP request to login, then notify XAML that it has data to render.
_myService->HTTPPostAsync(uri, json).then([](String^ outputJson){
String^ assets = MyParser::Parse(outputJSON);
// The Login has returned and we have our json output data
if(_delegate)
{
_delegate->UpdateUI(assets);
}
});
}
// In MyService.cpp
task<String^> MyService::HTTPPostAsync(Uri^ uri, String^ json)
{
return _httpRequest.PostAsync(uri,
json->Data(),
_cancellationTokenSource.get_token()).then([this](task<std::wstring> response)
{
try
{
if(_httpRequest.GetStatusCode() != 200) SM_LOG_WARNING("Status code=", _httpRequest.GetStatusCode());
String^ j = ref new String(response.get().c_str());
return j;
}
catch (Exception^ ex) .......;
return ref new String(L"");
}, task_continuation_context::use_current());
}
Edit: BTW, the error I get when I go to update the UI is:
"An invalid parameter was passed to a function that considers invalid parameters fatal."
In this case I am just trying to execute in my callback is
txtBox->Text = data;
It appears you are updating the UI thread from the wrong context. You can use task_continuation_context::use_arbitrary() to allow you to update the UI. See the "Controlling the Execution Thread" example in this document (the discussion of marshaling is at the bottom).
So, it turns out that when you have a continuation, if you don't specify a context after the lambda function, that it defaults to use_arbitrary(). This is in contradiction to what I learned in an MS video.
However by adding use_currrent() to all of the .then blocks that have anything to do with the GUI, my error goes away and everything is able to render properly.
My GUI calls a service which generates some tasks and then calls to an HTTP class that does asynchronous stuff too. Way back in the HTTP classes I use use_arbitrary() so that it can run on secondary threads. This works fine. Just be sure to use use_current() on anything that has to do with the GUI.
Now that you have my answer, if you look at the original code you will see that it already contains use_current(). This is true, but I left out a wrapping function for simplicity of the example. That is where I needed to add use_current().