Abel-Solutions/Abel.PropertyInjection

Property injection for .NET 5.

Abel Property Injection

Property injection is the answer to the question: "Why do I need to define fields or properties for my dependencies, then have them injected in a constructor, and then assign them? I don't want to repeat myself thrice, what can I do?!"

This is a typical example:

private readonly IEnvironmentRepository _environmentRepository;

private readonly IModelMapper<GroupServiceModel, GroupEntity> _groupMapper;

public EnvironmentService(
    IEnvironmentRepository environmentRepository,
    IModelMapper<GroupServiceModel, GroupEntity> groupMapper)
{
    _environmentRepository = environmentRepository;
    _groupMapper = groupMapper;
}

With property injection, the above block of code can be replaced with:

[Inject]
private readonly IEnvironmentRepository _environmentRepository;

[Inject]
private readonly IModelMapper<GroupServiceModel, GroupEntity> _groupMapper;

That's right, constructors are a thing of the past. Just slap some [Inject] attributes on there and you're good to go.

Supported member types

The observant reader might notice that the above example uses fields, not properties. Fields work just as well, property injection just sounds cooler.

The following member types are supported:

• All properties, no matter the type of setter, including no setter at all.
• All fields, including private readonly.

What about inheritance?

With inheritance, dependencies are often passed through multiple levels of constructors, making the code much messier than the above example.

Luckily, property injection works just as well in base classes, child classes and everything in-between. Just delete all those pesky constructors, and your dependencies will be taken care of, no matter where they are in the hierarchy. This is where property injection really shines!

Installation

1. Download the Abel.PropertyInjection Nuget package.
2. Add .UsePropertyInjection() to your host builder. If you don't have one, you can follow this guide to add it.

Host.CreateDefaultBuilder(args)
    .UsePropertyInjection()
    .ConfigureWebHostDefaults(webBuilder =>
        webBuilder.UseStartup<Startup>());

3. Delete your constructors.
4. Add [Inject] attributes to your fields and properties.