Logging to elmah.io from MAUI

We just started looking into .NET MAUI. If you want to go for the stable choice, check out the integration with Xamarin (the NuGet package is also in prerelease but more stable than the integration described on this page).

A quick way to get started with logging from MAUI to elmah.io is by installing the Elmah.Io.Blazor.Wasm NuGet package:

Install-Package Elmah.Io.Blazor.Wasm -IncludePrerelease

dotnet add package Elmah.Io.Blazor.Wasm --prerelease

<PackageReference Include="Elmah.Io.Blazor.Wasm" Version="4.*" />

paket add Elmah.Io.Blazor.Wasm

The name is, admittedly, misleading here. The Elmah.Io.Blazor.Wasm package contains a simplified version of the Elmah.Io.Extensions.Logging package that doesn't make use of the Elmah.Io.Client package to communicate with the elmah.io API.

Finally, configure the elmah.io logger in the MauiProgram.cs file:

public static MauiApp CreateMauiApp()
{
    var builder = MauiApp.CreateBuilder();
    builder
        .UseMauiApp<App>()
        // ...
        .Logging
            .AddElmahIo(options =>
            {
                options.ApiKey = "API_KEY";
                options.LogId = new Guid("LOG_ID");
            });

    return builder.Build();
}

Replace API_KEY with your API key (Where is my API key?) and LOG_ID with the ID of the log you want messages sent to (Where is my log ID?).

The logging initialization code will log all exceptions logged through ILogger both manually and by MAUI itself. MAUI supports dependency injection of the ILogger like most other web and mobile frameworks built on top of .NET.

Some exceptions are not logged through Microsoft.Extensions.Logging why you need to handle these manually. If you have worked with Xamarin, you probably know about the various exceptions-related events (like UnhandledException). Which event you need to subscribe to depends on the current platform. An easy approach is to use Matt Johnson-Pint's MauiExceptions class available here. When the class is added, logging uncaught exceptions is using a few lines of code:

// Replace with an instance of the ILogger
ILogger logger;

// Subscribe to the UnhandledException event and log it through ILogger
MauiExceptions.UnhandledException += (sender, args) =>
{
    var exception = (Exception)args.ExceptionObject;
    logger.LogError(exception, exception.GetBaseException().Message);
}

In case MauiExceptions doesn't trigger the UnhandledException event you can implement the code yourself. The event you need to implements depends on the platform where the application is executed. Look through the code for MauiExceptions to get inspiration. For Windows the code will look like this:

public class MauiProgram
{
    public static MauiApp CreateMauiApp()
    {
        var builder = MauiApp.CreateBuilder();

        // ...

        builder.Logging.AddElmahIo(options =>
        {
            options.ApiKey = "API_KEY";
            options.LogId = new Guid("LOG_ID");
        });

        var provider = builder.Build();

        AppDomain.CurrentDomain.FirstChanceException += (_, args) =>
        {
            var logger = provider.Services.GetRequiredService<ILogger<MauiProgram>>();
            logger.LogError(args.Exception, args.Exception.Message);
        };

        return provider;
    }
}

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