MAUI : LogMessage are not showing up anywhere

[nssidhu]

Description

I am using Inject ILogger and writing log message, but i don't see any output anywhere.

public ILogger _Logger { get; set; }

 protected override Task OnInitializedAsync()
{
    _Logger.LogInformation("Log Message from ILogger");
    System.Diagnostics.Debug.WriteLine("Log Message from Diganostic");
    Console.WriteLine("Log Message from console");
}

Is there something else to be configured in Blazor MAUI ?

Steps to Reproduce

1. Create Blazor MAUI App
2. In Index Page, after injecting the ILogger, inside OnInitializedAsync event

protected override Task OnInitializedAsync()
{
    _Logger.LogInformation("Log Message from ILogger");
    System.Diagnostics.Debug.WriteLine("Log Message from Diganostic");
    Console.WriteLine("Log Message from console");
}

Version with bug

6.0 (current)

Last version that worked well

Unknown/Other

Affected platforms

Android, Windows

Affected platform versions

Android emulator

Did you find any workaround?

No

Relevant log output

None

[javiercn]

@nssidhu thanks for contacting us.

Are you configuring a logging provider? Unlike asp.net core or blazor webassembly, I don't believe .NET Maui apps register a default ILoggerProvider implementation.

[nssidhu]

@nssidhu thanks for contacting us.

Are you configuring a logging provider? Unlike asp.net core or blazor webassembly, I don't believe .NET Maui apps register a default ILoggerProvider implementation.

No I am not doing anything extra when compared to Blazor Wasm.
Any links to documents which tell about how to configure it ?

[Eilon]

I just started taking a look at this and here's what I've found so far. I've tested a default MAUI / MAUI Blazor app by selectively adding certain loggers (or none at all) in MauiProgram.cs like so:

services.AddLogging(logging =>
{
    logging.AddDebug();
    //logging.AddConsole();
    //logging.AddSimpleConsole();
    //logging.AddSimpleConsole(o => o.ColorBehavior = LoggerColorBehavior.Disabled);
});

Logger	Windows	Android Sim on Win	iOS Sim	MacCatalyst
Default (None)	None	None	None	None
Debug	VS Output NS.ClassName: Information: TheLogMessage	VS Output [0:] NS.ClassName: Information: TheLogMessage	VS Mac Application Output NS.ClassName: Information: TheLogMessage	VS Mac Application Output NS.ClassName: Information: TheLogMessage
Console	None	VS Output [DOTNET] �[40m�[32minfo�[39m�[22m�[49m: NS.ClassName[0] [DOTNET] TheLogMessage	VS Mac Application Output 2022-06-14 20:49:10.853949-0700 MauiLogTest[31558:1500095] \^[[40m\^[[32minfo\^[[39m\^[[22m\^[[49m: NS.ClassName[0] TheLogMessage	VS Mac Application Output 2022-06-14 16:28:29.176 MauiLogTest[30459:1442744] �[40m�[32minfo�[39m�[22m�[49m: NS.ClassName[0] TheLogMessage
SimpleConsole	None	VS Output [DOTNET] �[40m�[32minfo�[39m�[22m�[49m: NS.ClassName[0] [DOTNET] TheLogMessage	VS Mac Application Output 2022-06-14 20:52:28.331803-0700 MauiLogTest[31637:1504813] \^[[40m\^[[32minfo\^[[39m\^[[22m\^[[49m: NS.ClassName[0] TheLogMessage	VS Mac Application Output 2022-06-14 20:32:28.651 MauiLogTest[30926:1475771] �[40m�[32minfo�[39m�[22m�[49m: NS.ClassName[0] TheLogMessage
SimpleConsole (Color=Disabled)	None	VS Output [DOTNET] info: NS.ClassName[0] [DOTNET] TheLogMessage	VS Mac Application Output 2022-06-14 20:54:20.232128-0700 MauiLogTest[31700:1508058] info: NS.ClassName[0] TheLogMessage	VS Mac Application Output 2022-06-14 20:36:54.491 MauiLogTest[30983:1479987] info: NS.ClassName[0] TheLogMessage

Notes:

• By default, MAUI apps have no default log sinks at all:

  maui/src/Core/src/Hosting/MauiAppBuilder.cs

  Lines 179 to 186 in 8d9d5f8

  	private void ConfigureDefaultLogging()
  	{
  	// By default, if no one else has configured logging, add a "no-op" LoggerFactory
  	// and Logger services with no providers. This way when components try to get an
  	// ILogger<> from the IServiceProvider, they don't get 'null'.
  	Services.TryAdd(ServiceDescriptor.Singleton<ILoggerFactory, NullLoggerFactory>());
  	Services.TryAdd(ServiceDescriptor.Singleton(typeof(ILogger<>), typeof(NullLogger<>)));
  	}

• For Android, iOS, and MacCatalyst, Console/SimpleConsole appear to be emitting ANSI color codes, which causes the output to be hard to read, because the VS output window and VS for Mac App Output window don't support ANSI color codes.
• I believe we should eventually come up with a set of loggers+options that work "out of the box" for all MAUI configurations, and enable them in the template, wrapped in #if DEBUG ... logging.AddMauiLogging() ... #endif, so that it has no default cost in MAUI itself, and is trivial for developers to tweak, if needed.
• Android Sim on Mac was not tested (not working on my machine 😢)
• Physical Android and iOS devices were not tested

[nssidhu]

@Eilon

Thanks for looking at this.

I really Like the Blazor Hybrid approach over XAML Native, this is opening up the doors for Web Developers to write Native Mobile Apps as well ability to write once and run everywhere.

!! Great work and kudos to entire team !!

Few question

I had to use builder prefix to service, which is different than what you have provided above.

 builder.Services.AddLogging(logging =>
        {
            logging.AddDebug();
            //logging.AddConsole();
            //logging.AddSimpleConsole();
            //logging.AddSimpleConsole(o => o.ColorBehavior = LoggerColorBehavior.Disabled);
        });

Do I need to install any nuget package to get this working ?

Severity Code Description Project File Line Suppression State
Error CS1061 'ILoggingBuilder' does not contain a definition for 'AddDebug' and no accessible extension method 'AddDebug' accepting a first argument of type 'ILoggingBuilder' could be found (are you missing a using directive or an assembly reference?)

[Eilon]

@nssidhu for the Debug logger, add a reference to this package: https://www.nuget.org/packages/Microsoft.Extensions.Logging.Debug

And you're right, in my case I had an extra variable to shorten the syntax. By default in MauiProgram.cs you would need to do builder.Services....

[Eilon]

The grid above is now filled out.

[Eilon]

Not sure what I was thinking earlier, but for some reason I thought we needed to conditionally add debug vs. console loggers. I completely forgot that the Debug logger just works everywhere!

So my proposal is quite simple:

The various .NET MAUI project templates need two changes:

1. Add a reference in the CSPROJ to <PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="6.0.0" />
2. Add these lines of code to MauiProgram.cs:

   #if DEBUG
   		builder.Logging.AddDebug();
   #endif

And that will enable a good default logging experience on every platform.

The code of the Microsoft.Extensions.Logging.Debug reference should be trivial because it brings in no real new dependencies (it depends on other things that are already referenced in all .NET MAUI projects), and the amount of code in it is trivial (a few dozen lines of mostly uninteresting code): https://github.com/dotnet/runtime/tree/main/src/libraries/Microsoft.Extensions.Logging.Debug/src

[Eilon]

PR to call AddDebug() in the project template: #8180