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TinyMvvm

TinyMvvm is a tiny helper library for using MVVM with .NET MAUI.

This is the repo containging the TinyMvvm for .NET MAUI. If you are looking for the code for TinyMvvm for Xamarin.Forms you find it in the old repo, https://github.com/TinyStuff/TinyMvvm

Get started

Initialize

In MauiProgram.cs add the following code to initialize TinyMvvm.

builder.UseTinyMvvm();

To use the ApplicationSleep and ApplicationResume overrides from TinyViewModel you need to add TinyApplication as the base class for your App class.

public partial class App : TinyApplication
{
	public App()
	{
		InitializeComponent();

		MainPage = new AppShell();
	}
}

If you want to run code asynchronous when the app starts you can override the Initialize method of TinyApplication.

public App()
{
	InitializeComponent();

	MainPage = new AppShell();
}

protected override async Task Initialize()
{
        
}

TinyView

TinyMvvm has a base view called TinyView that you need to use if you want to use the overides from TinyViewModel. TinyView has ContentPage as it's base class so you can use it exactly as a normal ContentPage.

<mvvm:TinyView xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:mvvm="clr-namespace:TinyMvvm;assembly=TinyMvvm.Maui"
             x:Class="TinyMvvm.Sample.Views.MainView"
             Title="Main View">

TinyViewModel

TinyMvvm has a class that you can use as the base class for your viewmodels. It is called TinyViewModel.

public partial class MainViewModel : TinyViewModel
{
}

CommunityToolkit.Mvvm

TinyMvvm has CommunityToolkit.Mvvm as a dependency. This means that TinyView has ObservableObject as it's base class and implementing the INotifyPropertyChanged interface via that base class. Read morea about CommunityToolkit.Mvvm here, https://learn.microsoft.com/en-us/dotnet/communitytoolkit/mvvm/

The Xamarin.Forms version of TinyMvvm had it's own implementation of ICommand. For .NET MAUI that implementation is removed, and the recommendation is to use the one from CommunityToolkit instead.

Methods to override

Initialize This method runs when the viewmodel is set as BindingContext of a view. This method can be used for initial load of data. Note that NavigationParameter and QueryParameters is not set when this method runs.

public override Task Initialize()
{

}

OnParameterSet This metod will run after that navigation parameters has been set. Read more about that under Navigation.

public override async Task OnParameterSet()
{
    IsBusy = true;

    if (NavigationParameter is City city)
    {
        City = city;
    }
    else
    {
        var text = QueryParameters["city"];
        City = await cityService.Get(text.ToString());
    }

    IsBusy = false;
 }

OnAppearing OnAppearing will run when the view is a appearing, this method is triggerd from OnAppearing in TinyView.

public override Task OnAppearing()
{
}

OnDisappearing OnDisappearing will run when the view is a appearing, this method is triggerd from OnDisappearing in TinyView.

public override Task OnDisappearing()
{
}

OnApplicationResume OnApplicationResume will run when/after the application returns from the background. It is triggered by OnSleep from the TinyApplication class. Because if that, your App class need to have TinyApplication as base class.

public override Task OnApplicationResume()
{
}

OnApplicationSleep OnApplicationSleep will run when/before the application goes to the background. It is triggered by OnSleep from the TinyApplication class. Because if that, your App class need to have TinyApplication as base class.

public override Task OnApplicationSleep()
{
}

Navigation

TinyViewModel has a navigation helper that you can use in your viewmodels. It is more a less a wrapper around Shell navigation, but with some helpers for parameter. But you should pass a route to it that you have defined in your shell file or defined with the Routing.RegisterRoute method.

You can either pass a parameter or use a querystring or do both.

[RelayCommand]
public async Task NavigateToPage()
{
    var monkey = new Monkey();

    await Navigation.NavigateTo("//DetailsPage?id=1", monkey); 
}

TinyViewModel has two ways to access navigation parameters, the QueryParameters property and the NavigationParameter property. QueryParameters is of type Dictionary<string, object> and NavigationParameter is of type object. Querystrings will be splitted up and added to the QueryParameters property. Single parameters will be in the NavigationParameters property. After that properties are set the **OnParameterSet method is called. To access the properties you should override OnParameterSet method.

public override async Task OnParameterSet()
{
    var id = QueryParameters["id"] as string;
    var monkey = NavigationParameter as Monkey;
}

IsBusy

TinyViewModel has a IsBusy and a IsNotBusy property that you can use in your viewmodels and views. IsNotBusy is read-only and is updated when you set IsBusy.

Video

In this video you can watch Daniel Hindrikes talk about TinyMvvm, https://youtu.be/kqsoG2Ii4w4.

Contribute

You are very welcome to contribute to TinyMvvm. If you want to add a new feature we would like if you create an issue first so we can discuss the the feature before you spend time to implement it.