Implement Logging Service in .NET MAUI

Hello Devs, In this blog we'll learn that how to implement file based Logging service in .NET MAUI without using any external library/packages.

First of all, add below code in the MainPage.xaml.cs file which is located at the root of project directory.

using System.Diagnostics;
using System.Reflection;
using System.Runtime.ExceptionServices;
namespace logs;

public partial class MainPage : ContentPage
{

    public MainPage()
    {
        InitializeComponent();

        AppDomain.CurrentDomain.FirstChanceException += CurrentDomain_FirstChanceException;
    }

    private void CurrentDomain_FirstChanceException(object sender, FirstChanceExceptionEventArgs e)
    {
        if (e.Exception is Exception ex)
        {
            LogException(ex);
        }
    }

    private void LogException(Exception ex)
    {
        string logsFilePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "app_logs.txt");
        try
        {
            // Get information about the method that caused the exception.        
            StackFrame sf = new StackFrame(1);
            MethodBase method = sf.GetMethod();
            int line = sf.GetFileLineNumber();

            // Create a log message with thread ID, timestamp, method information, and the exception message.

            string exMsg = Environment.CurrentManagedThreadId + " ~ " + DateTime.Now.ToString() + method.DeclaringType.FullName + "::" + line + "-" + GetErrorMessage(ex);

            // Append the log message to the specified log file.
            File.AppendAllText(logsFilePath, exMsg + Environment.NewLine + Environment.NewLine);
        }
        catch (Exception exe)
        {
            // If there's an exception while logging, write the error message to the console.
            Console.WriteLine(exe.Message);
        }
    }

    private string GetErrorMessage(Exception ex)
    {
        if (ex != null)
        {
            string message = ex.StackTrace + " " + ex.Message;
            if (ex.InnerException != null)
            {
                message += "~ Caused By" + GetErrorMessage(ex.InnerException);
            }
            return message;
        }

        return string.Empty;
    }

}

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Let's Understand above Code.

=> AppDomain.CurrentDomain.FirstChanceException += CurrentDomain_FirstChanceException :

• This line subscribes the CurrentDomain_FirstChanceException method to the FirstChanceException event of the current application domain. This event is raised whenever an exception is thrown in the application.

=> LogException(Exception ex) :

• This method is responsible for logging exceptions to a file.
• It constructs a log file path (logsFilePath) within the application's base directory and attempts to log the exception information to it.
• It uses StackFrame to retrieve information about the method that caused the exception, such as the method name and line number.

=> GetErrorMessage(Exception ex):

• This is a recursive method that retrieves the error message and stack trace for an exception, including any inner exceptions.

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After that use try catch block in the code where you want to get logs if any exception occurs. here we add try-catch block in the MainPage.xaml.cs file for demonstrate.

private void OnCounterClicked(object sender, EventArgs e)
    {
        throw new Exception("Counter Button Clicked!");
    }

    private void OnGetFilesClicked(object sender, EventArgs e)
    {
        try
        {
               // there is no any directory exist , so exception will be occured
            string path = "/demo_logs";
            Directory.GetFiles(path);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }

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=> Logging file location (according to specified path in the code):

• for windows --> bin\Debug\net7.0-windows10.0.19041.0\win10-x64\app_logs.txt
• for MacOs --> bin/Debug/net7.0-maccatalyst/maccatalsyt-x64/[Project_Name].app/Contents/MonoBundle/app_logs.txt

=> Logs :

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You can find the necessary code in the repository mentioned below.

GithHub Repository

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