Is there any Error Logging Framework in Mvvmcross?

Question

I am building a cross platform application using Mvvmcross. And I wanted to know if there is any in built error logging framework already existing in Mvvmcross library.

I am looking for something which will log all the errors into a file in the application data. I can simply built my own in the Windows Store app but how do i log the errors which arise in Core Library as I cant access Application Data folder there ?

I saw one Mvx.Error() method. What is the purpose of it ?

Answer 1

I saw one Mvx.Error() method. What is the purpose of it ?

Mvx.Trace(), Mvx.Warning() and Mvx.Error() all provide simple APIs to log information.

The log output itself goes to a singleton registered during Setup. You can easily implement your own implementation of this:

public class DebugTrace : IMvxTrace
{
    public void Trace(MvxTraceLevel level, string tag, Func<string> message)
    {
        Debug.WriteLine(tag + ":" + level + ":" + message());
    }

    public void Trace(MvxTraceLevel level, string tag, string message)
    {
        Debug.WriteLine(tag + ":" + level + ":" + message);
    }

    public void Trace(MvxTraceLevel level, string tag, string message, params object[] args)
    {
        try
        {
            Debug.WriteLine(string.Format(tag + ":" + level + ":" + message, args));
        }
        catch (FormatException)
        {
            Trace(MvxTraceLevel.Error, tag, "Exception during trace of {0} {1} {2}", level, message);
        }
    }
}

and this can easily be registered during Setup:

public class Setup : MvxAndroidSetup
{
    public Setup(Context applicationContext) : base(applicationContext)
    {
    }

    protected override IMvxApplication CreateApp()
    {
        return new Core.App();
    }

    protected override IMvxTrace CreateDebugTrace()
    {
        return new DebugTrace();
    }
}

In apps, I generally implement my own app specific logging in the Core class using one or more unique tags - this allows me to then filter on the tag - e.g. I might have something like:

public static class MyApp
{
    public static void NetTrace(string message, params object[] args)
    {
        Mvx.TaggedTrace("MyAppNet", message, args);
    }

    public static void NetError(string message, params object[] args)
    {
        Mvx.TaggedError("MyAppNet", message, args);
    }

    public static void VmTrace(string message, params object[] args)
    {
        Mvx.TaggedTrace("MyAppVm", message, args);
    }

    public static void VmError(string message, params object[] args)
    {
        Mvx.TaggedError("MyAppVm", message, args);
    }
}

For logging outside of the debugger, there are several libraries around - e.g. things like NLog - which you can easily hook up to MvxTrace