Please suggest proper way of handling server side exceptions when ViewModel is used in Client side blazor application

[vijaygill]

I have a following code which removes an item from a BusinessList and saves the list. I do this to achieve deleting of records.

Now to just commented out the Update function in my BusinessList as if I forgot to implement it.

The ViewModel seems to have exception and also error message which I show in the UI side.

But the standard "Reload" element of Blazor application also pops up which seems to show the exception is treated as unhandled exception.

Can you please suggest proper way of handling server side exceptions when ViewModel is used in Client side blazor application.

It works fine in server side Blazor application though.

     private async Task DeleteItem(TSearchItem item)
    {
        // we are deleting via EditableRoot list so deleting via vm has to be done in a different way
        // list.Remove(item);//cannot directly mark a child as Deleted. Use Parent collection.

        try
        {
            if (await DialogService.Confirm("Delete?") == true)
            {
                vmList.Model.Remove(item);
                await vmList.SaveAsync();
                await UpdateGrid();
                await InvokeAsync(() => { StateHasChanged(); });
            }
        }
        catch (Exception ex)
        {
            status = ex.ToString();
        }
    }

[rockfordlhotka]

The exception should be handled, perhaps something else is happening?

csla/Source/Csla.Blazor/ViewModel.cs

Line 115 in e059808

public async Task SaveAsync()

[rockfordlhotka]

I'd suggest putting a try..catch around your code in DeleteItem to see what exception is occurring. It could be something from data binding.

[vijaygill]

Hi Rocky,

I tried that too already (I have updated the original post). The variably "status" is displayedin the UI.

The code does not go into "catch" block!

I will dig further and see if I can find anything.

Thanks!

[vijaygill]

@rockfordlhotka

Hi Rocky,

Cleaned up stack-trace is shown below

and this happens just when await vmList.SaveAsync(); is executed while single stepping through the code.

blazor.webassembly.js:1 Csla.DataPortalException: DataPortal.Update failed on the server
blazor.webassembly.js:1    at Csla.DataPortalClient.HttpProxy.Update(Object obj, DataPortalContext context, Boolean isSync)
blazor.webassembly.js:1    at Csla.DataPortal`1.<DoUpdateAsync>d__30[[BlazorBusinessApp.Business.BusinessObjects.WeatherForecastList, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
blazor.webassembly.js:1    at Csla.DataPortal`1.<UpdateAsync>d__40[[BlazorBusinessApp.Business.BusinessObjects.WeatherForecastList, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
blazor.webassembly.js:1    at Csla.DataPortal.<UpdateAsync>d__33`1[[BlazorBusinessApp.Business.BusinessObjects.WeatherForecastList, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
blazor.webassembly.js:1    at Csla.BusinessListBase`2.<SaveAsync>d__75[[BlazorBusinessApp.Business.BusinessObjects.WeatherForecastList, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[BlazorBusinessApp.Business.BusinessObjects.WeatherForecast, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
blazor.webassembly.js:1    at Csla.BusinessListBase`2.<SaveAsync>d__74[[BlazorBusinessApp.Business.BusinessObjects.WeatherForecastList, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[BlazorBusinessApp.Business.BusinessObjects.WeatherForecast, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
blazor.webassembly.js:1    at Csla.BusinessListBase`2.<Csla-Core-ISavable-SaveAsync>d__91[[BlazorBusinessApp.Business.BusinessObjects.WeatherForecastList, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[BlazorBusinessApp.Business.BusinessObjects.WeatherForecast, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
blazor.webassembly.js:1    at Csla.Blazor.ViewModel`1.<DoSaveAsync>d__22[[BlazorBusinessApp.Business.BusinessObjects.WeatherForecastList, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
blazor.webassembly.js:1    at Csla.Blazor.ViewModel`1.<SaveAsync>d__21[[BlazorBusinessApp.Business.BusinessObjects.WeatherForecastList, BlazorBusinessApp.Business, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
blazor.webassembly.js:1 Csla.Server.DataPortalException: DataPortal.Update failed on the server
blazor.webassembly.js:1    at Csla.BusinessListBase`2.DataPortal_Update()
blazor.webassembly.js:1    at Csla.Reflection.ServiceProviderMethodCaller.CallMethodTryAsync(Object obj, ServiceProviderMethodInfo method, Object[] parameters)
blazor.webassembly.js:1    at Csla.Reflection.LateBoundObject.CallMethodTryAsyncDI[T](Boolean isSync, Object[] parameters)
blazor.webassembly.js:1    at Csla.Server.DataPortalTarget.InvokeOperationAsync[T](Object criteria, Boolean isSync)
blazor.webassembly.js:1    at Csla.Server.DataPortalTarget.UpdateAsync(Boolean isSync)
blazor.webassembly.js:1    at Csla.Server.SimpleDataPortal.Update(Object obj, DataPortalContext context, Boolean isSync)
blazor.webassembly.js:1    at Csla.Server.DataPortal.NewDataPortalException(String message, Exception innerException, Object businessObject)
blazor.webassembly.js:1    at Csla.Server.SimpleDataPortal.Update(Object obj, DataPortalContext context, Boolean isSync)
blazor.webassembly.js:1    at Csla.Server.DataPortalSelector.Update(Object obj, DataPortalContext context, Boolean isSync)
blazor.webassembly.js:1    at Csla.Server.DataPortal.Update(Object obj, DataPortalContext context, Boolean isSync)
blazor.webassembly.js:1    at Csla.Server.Hosts.HttpPortal.Update(UpdateRequest request)
blazor.webassembly.js:1    at Csla.Server.Hosts.HttpPortalController.CallPortal(String operation, Object request)
blazor.webassembly.js:1    at Csla.Server.Hosts.HttpPortalController.InvokeTextPortal(String operation, Stream requestStream, Stream responseStream)
blazor.webassembly.js:1 Csla.Reflection.CallMethodException: WeatherForecastList.DataPortal_Update method call failed
blazor.webassembly.js:1    at Csla.BusinessListBase`2.DataPortal_Update()
blazor.webassembly.js:1    at Csla.Reflection.ServiceProviderMethodCaller.CallMethodTryAsync(Object obj, ServiceProviderMethodInfo method, Object[] parameters)
blazor.webassembly.js:1    at Csla.Reflection.LateBoundObject.CallMethodTryAsyncDI[T](Boolean isSync, Object[] parameters)
blazor.webassembly.js:1    at Csla.Server.DataPortalTarget.InvokeOperationAsync[T](Object criteria, Boolean isSync)
blazor.webassembly.js:1    at Csla.Server.DataPortalTarget.UpdateAsync(Boolean isSync)
blazor.webassembly.js:1    at Csla.Server.SimpleDataPortal.Update(Object obj, DataPortalContext context, Boolean isSync)
blazor.webassembly.js:1    at Csla.BusinessListBase`2.DataPortal_Update()
blazor.webassembly.js:1    at Csla.Reflection.ServiceProviderMethodCaller.CallMethodTryAsync(Object obj, ServiceProviderMethodInfo method, Object[] parameters)

[rockfordlhotka]

Is this with a remote data portal, or are you running your data access code within wasm?

[vijaygill]

This is with remote data portal (Blazor Client side/Server side with App server). I am following your CSLA Blazor book (CSLA-Blazor-200519.pdf).
The solution structure is as exactly suggested in the book.

Blazor (both Client and Server side) use App Server which uses DAL to access data.

Actually I have picked up CSLA again after a gap of 5 years (last time it was with WinForms) so I am not experimenting with stuff and just sticking to basics before I get a grasp of the things.

[vijaygill]

Hi again Rocky,
I think I have found the cause. The following line causes this to happen

csla/Source/Csla.Blazor/ViewModel.cs

Line 133 in e059808

Console.Error.WriteLine(ex.ToString());

I created a copy of your ViewModel (called it ViewModelPlus) in my own project and set it up for DI etc. During single-stepping I found the Blazor standard error handler kicking in when the above line is executed.

I removed the line and everything just seemed to work fine!

[rockfordlhotka]

Oh, well that line shouldn't be there anyway!! Definitely a bug!

#2347

I'll happily accept PR to fix it 😉

[vijaygill]

Hi Rocky.

PR has been raised.

Thank you again for prompt and helpful replies.