AttributeAutoDI

🌟 Attribute-based automatic dependency injection library for .NET

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README-KR

README-KR

Nuget

NUGET

dotnet add package AttributeAutoDI --version 1.0.1

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Sample

Sample

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💡 Motivation

The default DI container in ASP.NET Core is simple and powerful, but having to call builder.Services.AddXXX<>() repeatedly introduces a few pain points:

❌ The more services you implement, the longer and harder your Program.cs becomes to manage

❌ Handling multiple implementations of the same interface requires verbose, error-prone registration

❌ Service intent is not self-explanatory – registration and class definition are separated

👉 What if... classes could declare how they want to be injected? AttributeAutoDI was born from this idea.

It is built on the following principles: ✅ Services should declare their own lifecycle and purpose

✅ Multiple implementations should be clearly handled via [Primary] or [Named]

✅ We should reduce boilerplate code in Program.cs without sacrificing readability

Our goal is to simplify Program.cs and Startup.cs as much as possible so you can trust the system to "just work."

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🧾 Requirements

• .NET 6.0 or later
• Compatible with Microsoft.Extensions.DependencyInjection (ASP.NET Core, Console apps, etc.)

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🔥 Features

✅ Automatic registration via [Singleton], [Scoped], and [Transient]

⭐ [Primary] support for selecting default implementation

🏷️ [Named] support for explicit injection via constructor parameters

🛠️ [Options("Section")] for automatic configuration binding

👾 Executes configuration methods marked with [Execute] inside classes decorated with [PreConfiguration] or [PostConfiguration].

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🚀 Usage

1. Register the extension

builder.Services.AddAttributeDependencyInjection(builder.Configuration);

or

builder.Services.AddAttributeDependencyInjection(builder.Configuration,typeof(Program).Assembly);

Internally, it expands to:

public static class AttributeInjectionExtension
{
    public static void AddAttributeDependencyInjection(
    this IServiceCollection services,
    IConfiguration configuration,
    Assembly? assembly = null
)
{
    assembly ??= Assembly.GetEntryAssembly();

    services.UsePreConfiguration(assembly!);

    services.UseOptionsBindingInjection(configuration, assembly!);
    services.UseAttributeInjection(assembly!);
    services.UsePrimaryInjection();
    services.UseNameParameterInjection(assembly!);
    services.Replace(ServiceDescriptor.Transient<IControllerActivator, NamedControllerActivator>());

    services.UsePostConfiguration(assembly!);
}

Execution Flow

1. Execute methods under [PreConfiguration] classes

2. Register [Options] bindings

3. Register class dependencies marked with [Singleton], [Transient], or [Scoped]

4. Register [Primary] dependencies

5. Register constructor parameter classes and controller activators with [Named]

6. Execute methods under [PostConfiguration] classes

⚠️ Important: Register in correct order!

✔️ This works as expected:

builder.Service.AddSingleton...
builder.Service.AddAttributeDependencyInjection 

❌ This may not work correctly:

builder.Service.AddAttributeDependencyInjection
builder.Service.AddSingleton...

If you use both manual and attribute-based registration, always call AddAttributeDependencyInjection() after manual registrations.

2. Attribute-based Auto registration - [Singleton], [Transient], [Scoped]

[Singleton]
public class MyService : IMyService
{
    public string Get() => "hello";
}

This is equivalent to:

builder.Services.AddSingleton<IMyService, MyService>();

3. Primary service selection - [Primary]

[Singleton]
public class MyService : IMyService
{
    public string Get() => "hello";
}

[Primary]
[Singleton]
public class MyPrimaryService : IMyService
{
    public string Get() => "I am primary";
}

When injecting IMyService, the system will prefer MyPrimaryService.

4. Named injection - [Named]

[Singleton]
public class MyService : IMyService
{
    public string Get() => "hello";
}

This will register myService (default camel-case name). Or set custom name:

[Singleton("myNamedService")]
public class MyService : IMyService
{
    public string Get() => "hello";
}

Then inject with:

[Singleton]
public class TestFacade([Named("myNamedService")]IMyservice myservice)
{
...
}
// myservice == MyService

Named injection works in registered Class

5. Options binding via attribute - [Options]

[Options("Sample:Sample")]
public class SampleOption
{
    public string Sample { get; set; } = "";
}

This is equivalent to:

builder.Services.Configure<SampleOption>(configuration.GetSection("Sample:Sample"));

Then you can inject it with:

public class SampleController(
    IOptions<SampleOption> sampleOption) ...

6. Configuration Execution - [PreConfiguration], [PostConfiguration], [Execute]

You can run setup methods before or after AddAttributeDependencyInjection using [Execute] methods.

The execution order is:

PreConfiguration → AddAttributeDependencyInjection → PostConfiguration

[PreConfiguration] //or [PostConfiguration]
public static class Configuration{
    [Execute]
    public static void TestConfig1(IServiceCollection service){
        ...
    }

    [Execute]
    public static void TestConfig2(this IServiceCollection service){
    ...
    }
    
    [Execute]
    public static void TestConfig3(IServiceCollection service, IConfiguration configuration){
        ...
    }

    [Execute]
    public static void TestConfig4(this IServiceCollection service, IConfiguration configuration){
    ...
    }
}

✅ Only these four method signatures are supported.

ℹ️ Return types are ignored — any return type is allowed but not used.

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🧪 Examples

Check out the AttributeAutoDI.Sample project for practical examples.

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🙌 Contributing

Found a bug? Have an improvement idea? Feel free to open an issue or submit a pull request.

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📄 License

MIT License Copyright (c) 2025