ASP.NET Core Razor - Global Exception Handler

Question

I have the following which partially works in the .cshtml.cs but not the .cshtml file:

Do I need to change my GlobalExceptionFilter or do I need to add something else to catch the .cshtml errors?

For both of the errors they do redirect to the /Error page.

public class GlobalExceptionFilter : IExceptionFilter
{       
    public void OnException(ExceptionContext context)
    {
        LogError(context.Exception);
    }
}

In Startup.cs:

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvcOptions(options =>
                {
                    options.Filters.Add<GlobalExceptionFilter>();
                });
}

---

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/Error");
        }
}

In Index.cshtml.cs:

public void OnGet()
{
    throw new Exception("Test"); //This hits GlobalExceptionFilter
}

In Index.cshtml:

@{
    throw new Exception("Test"); //This does NOT hit GlobalExceptionFilter
}

Thanks in advance

Answer 1

From the doc:

Exception filters apply global policies to unhandled exceptions that occur before the response body has been written to.

Exception filters:

Are good for trapping exceptions that occur within actions.

Are not as flexible as error handling middleware.

Here you can use a custom ExceptionHandler middleware like below:

public class CustomExceptionHandler
{
    private readonly IWebHostEnvironment _environment;
    
    public CustomExceptionHandler(IWebHostEnvironment environment)
    {
        _environment = environment;
    }

    public async Task Invoke(HttpContext httpContext)
    {
            var feature = httpContext.Features.Get<Microsoft.AspNetCore.Diagnostics.IExceptionHandlerFeature>();
            var error = feature?.Error;

            if(error != null)
            {                    
                LogError(error);
                throw error;
            }

            await Task.CompletedTask;
    }
}

Use it in the startup.cs

app.UseExceptionHandler(new ExceptionHandlerOptions
{
    ExceptionHandler = new CustomExceptionHandler(env).Invoke
});