maui-dependency-injection

Name: maui-dependency-injection
Author: managedcode

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How to install maui-dependency-injection?

managedcode/dotnet-skills/maui-dependency-injection

$npx -y skills add managedcode/dotnet-skills --skill maui-dependency-injection

Installs into the current project.

Summary

Guidance for configuring dependency injection in .NET MAUI apps — service registration in MauiProgram.cs, lifetime selection (Singleton / Transient / Scoped), constructor injection, Shell navigation auto-resolution, platform-specific registrations, and testability patterns. USE F

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SKILL.md

1	# Dependency Injection in .NET MAUI
2
3	.NET MAUI uses the same `Microsoft.Extensions.DependencyInjection` container as ASP.NET Core. All service registration happens in `MauiProgram.CreateMauiApp()` on `builder.Services`. The container is built once at startup and is immutable thereafter.
4
5	## When to Use
6
7	- Registering services, ViewModels, and Pages in `MauiProgram.cs`
8	- Choosing between `AddSingleton`, `AddTransient`, and `AddScoped`
9	- Wiring constructor injection for Pages and ViewModels
10	- Leveraging Shell navigation to auto-resolve DI-registered Pages
11	- Registering platform-specific service implementations with `#if` directives
12	- Designing interfaces for testable service layers
13
14	## When Not to Use
15
16	- XAML data-binding syntax or compiled bindings — use the maui-data-binding skill
17	- Shell route registration and query parameters — use the maui-shell-navigation skill
18	- Mocking frameworks or test runners — use standard .NET testing tools (xUnit, NUnit, MSTest) and mocking libraries (NSubstitute, Moq)
19
20	## Inputs
21
22	- A .NET MAUI project with a `MauiProgram.cs` file
23	- Knowledge of which services, ViewModels, and Pages need registration
24	- Target platforms (Android, iOS, Mac Catalyst, Windows) for conditional registrations
25
26	## Workflow
27
28	1. Identify all services, ViewModels, and Pages that need to participate in dependency injection.
29	2. Choose the correct lifetime for each type — `AddSingleton` for shared services, `AddTransient` for Pages and ViewModels.
30	3. Register all types in `MauiProgram.CreateMauiApp()` on `builder.Services`, grouping by category (services, HTTP, ViewModels, Pages).
31	4. Register Pages as Shell routes in `AppShell.xaml.cs` so Shell navigation auto-resolves the full dependency graph.
32	5. Wire each Page to its ViewModel via constructor injection, assigning the ViewModel as `BindingContext`.
33	6. Add platform-specific registrations with `#if` directives, ensuring every target platform is covered or has a fallback.
34	7. Verify resolution works by running the app and confirming no `null` dependencies or missing-registration exceptions at runtime.
35
36	---
37
38	## Lifetime Selection
39
40	\| Lifetime \| When to Use \| Typical Types \|
41	\|---\|---\|---\|
42	\| `AddSingleton<T>()` \| Shared state, expensive to create, app-wide config \| `HttpClient` factory, settings service, database connection \|
43	\| `AddTransient<T>()` \| Lightweight, stateless, or needs a fresh instance per use \| Pages, ViewModels, per-call API wrappers \|
44	\| `AddScoped<T>()` \| Per-scope lifetime with manually created `IServiceScope` \| Scoped unit-of-work (rare in MAUI) \|
45
46	Key rule: Register Pages and ViewModels as Transient. Register shared services as Singleton.
47
48	> ⚠️ Avoid `AddScoped` unless you manually manage `IServiceScope`. MAUI has no built-in request scope like ASP.NET Core. A Scoped registration without an explicit scope silently behaves as a Singleton, leading to subtle bugs.
49
50	---
51
52	## Registration Pattern in MauiProgram.cs
53
54	```csharp
55	public static MauiApp CreateMauiApp()
56	{
57	var builder = MauiApp.CreateBuilder();
58	builder.UseMauiApp<App>();
59
60	// Services — Singleton for shared state
61	builder.Services.AddSingleton<IDataService, DataService>();
62	builder.Services.AddSingleton<ISettingsService, SettingsService>();
63
64	// HTTP — use typed or named clients via IHttpClientFactory
65	// Requires NuGet: Microsoft.Extensions.Http
66	builder.Services.AddHttpClient<IApiClient, ApiClient>();
67
68	// ViewModels — Transient for fresh state per navigation
69	builder.Services.AddTransient<MainViewModel>();
70	builder.Services.AddTransient<DetailViewModel>();
71
72	// Pages — Transient so constructor injection fires each time
73	builder.Services.AddTransient<MainPage>();
74	builder.Services.AddTransient<DetailPage>();
75
76	return builder.Build();
77	}
78	```
79
80	---
81
82	## Constructor Injection
83
84	Inject dependencies through constructor parameters. The container resolves them automatically when the type is itself resolved from DI.
85
86	```csharp
87	public class MainViewModel
88	{
89	private readonly IDataService _dataService;
90
91	public MainViewModel(IDataService dataService)
92	{
93	_dataService = dataService;
94	}
95
96	public async Task LoadAsync() => Items = await _dataService.GetItemsAs

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maui-dependency-injection

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View on GitHub

How to install maui-dependency-injection?

managedcode/dotnet-skills/maui-dependency-injection

$npx -y skills add managedcode/dotnet-skills --skill maui-dependency-injection

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# Dependency Injection in .NET MAUI
2
3	.NET MAUI uses the same `Microsoft.Extensions.DependencyInjection` container as ASP.NET Core. All service registration happens in `MauiProgram.CreateMauiApp()` on `builder.Services`. The container is built once at startup and is immutable thereafter.
4
5	## When to Use
6
7	- Registering services, ViewModels, and Pages in `MauiProgram.cs`
8	- Choosing between `AddSingleton`, `AddTransient`, and `AddScoped`
9	- Wiring constructor injection for Pages and ViewModels
10	- Leveraging Shell navigation to auto-resolve DI-registered Pages
11	- Registering platform-specific service implementations with `#if` directives
12	- Designing interfaces for testable service layers
13
14	## When Not to Use
15
16	- XAML data-binding syntax or compiled bindings — use the maui-data-binding skill
17	- Shell route registration and query parameters — use the maui-shell-navigation skill
18	- Mocking frameworks or test runners — use standard .NET testing tools (xUnit, NUnit, MSTest) and mocking libraries (NSubstitute, Moq)
19
20	## Inputs
21
22	- A .NET MAUI project with a `MauiProgram.cs` file
23	- Knowledge of which services, ViewModels, and Pages need registration
24	- Target platforms (Android, iOS, Mac Catalyst, Windows) for conditional registrations
25
26	## Workflow
27
28	1. Identify all services, ViewModels, and Pages that need to participate in dependency injection.
29	2. Choose the correct lifetime for each type — `AddSingleton` for shared services, `AddTransient` for Pages and ViewModels.
30	3. Register all types in `MauiProgram.CreateMauiApp()` on `builder.Services`, grouping by category (services, HTTP, ViewModels, Pages).
31	4. Register Pages as Shell routes in `AppShell.xaml.cs` so Shell navigation auto-resolves the full dependency graph.
32	5. Wire each Page to its ViewModel via constructor injection, assigning the ViewModel as `BindingContext`.
33	6. Add platform-specific registrations with `#if` directives, ensuring every target platform is covered or has a fallback.
34	7. Verify resolution works by running the app and confirming no `null` dependencies or missing-registration exceptions at runtime.
35
36	---
37
38	## Lifetime Selection
39
40	\| Lifetime \| When to Use \| Typical Types \|
41	\|---\|---\|---\|
42	\| `AddSingleton<T>()` \| Shared state, expensive to create, app-wide config \| `HttpClient` factory, settings service, database connection \|
43	\| `AddTransient<T>()` \| Lightweight, stateless, or needs a fresh instance per use \| Pages, ViewModels, per-call API wrappers \|
44	\| `AddScoped<T>()` \| Per-scope lifetime with manually created `IServiceScope` \| Scoped unit-of-work (rare in MAUI) \|
45
46	Key rule: Register Pages and ViewModels as Transient. Register shared services as Singleton.
47
48	> ⚠️ Avoid `AddScoped` unless you manually manage `IServiceScope`. MAUI has no built-in request scope like ASP.NET Core. A Scoped registration without an explicit scope silently behaves as a Singleton, leading to subtle bugs.
49
50	---
51
52	## Registration Pattern in MauiProgram.cs
53
54	```csharp
55	public static MauiApp CreateMauiApp()
56	{
57	var builder = MauiApp.CreateBuilder();
58	builder.UseMauiApp<App>();
59
60	// Services — Singleton for shared state
61	builder.Services.AddSingleton<IDataService, DataService>();
62	builder.Services.AddSingleton<ISettingsService, SettingsService>();
63
64	// HTTP — use typed or named clients via IHttpClientFactory
65	// Requires NuGet: Microsoft.Extensions.Http
66	builder.Services.AddHttpClient<IApiClient, ApiClient>();
67
68	// ViewModels — Transient for fresh state per navigation
69	builder.Services.AddTransient<MainViewModel>();
70	builder.Services.AddTransient<DetailViewModel>();
71
72	// Pages — Transient so constructor injection fires each time
73	builder.Services.AddTransient<MainPage>();
74	builder.Services.AddTransient<DetailPage>();
75
76	return builder.Build();
77	}
78	```
79
80	---
81
82	## Constructor Injection
83
84	Inject dependencies through constructor parameters. The container resolves them automatically when the type is itself resolved from DI.
85
86	```csharp
87	public class MainViewModel
88	{
89	private readonly IDataService _dataService;
90
91	public MainViewModel(IDataService dataService)
92	{
93	_dataService = dataService;
94	}
95
96	public async Task LoadAsync() => Items = await _dataService.GetItemsAs

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