Are you building scalable, testable applications in ASP.NET Core?
Then you must embrace the 𝗗𝗲𝗽𝗲𝗻𝗱𝗲𝗻𝗰𝘆 𝗜𝗻𝘃𝗲𝗿𝘀𝗶𝗼𝗻 𝗣𝗿𝗶𝗻𝗰𝗶𝗽𝗹𝗲 (𝗗𝗜𝗣) and implement it using 𝗗𝗲𝗽𝗲𝗻𝗱𝗲𝗻𝗰𝘆 𝗜𝗻𝗷𝗲𝗰𝘁𝗶𝗼𝗻 (𝗗𝗜).

Here’s a simple, clear example to help you understand how both work together in a real ASP.NET Core project. 🚀

🔹 Step 1: Define an Interface and Implementation (DIP)

public interface IMessageService
{
string GetMessage();
}

public class HelloMessageService : IMessageService
{
public string GetMessage()
{
return "Hello from the message service!";
}
}

💡 Your controller now depends on an abstraction (interface) – this is 𝗗𝗲𝗽𝗲𝗻𝗱𝗲𝗻𝗰𝘆 𝗜𝗻𝘃𝗲𝗿𝘀𝗶𝗼𝗻 𝗣𝗿𝗶𝗻𝗰𝗶𝗽𝗹𝗲 in action.

🔸 Step 2: Inject the Dependency into the Controller (DI)

public class MessageController : ControllerBase
{
private readonly IMessageService _messageService;

public MessageController(IMessageService messageService)
{
    _messageService = messageService;
}

public IActionResult Get()
{
    return Ok(_messageService.GetMessage());
}

}

This is 𝗰𝗼𝗻𝘀𝘁𝗿𝘂𝗰𝘁𝗼𝗿 𝗶𝗻𝗷𝗲𝗰𝘁𝗶𝗼𝗻, one of the most common forms of 𝗗𝗲𝗽𝗲𝗻𝗱𝗲𝗻𝗰𝘆 𝗜𝗻𝗷𝗲𝗰𝘁𝗶𝗼𝗻 in ASP.NET Core.

🔹 Step 3: Register the Service in Program.cs

builder.Services.AddScoped();

Now your service is automatically injected by the .𝗡𝗘𝗧 𝗖𝗼𝗿𝗲 𝗯𝘂𝗶𝗹𝘁-𝗶𝗻 𝗗𝗜 𝗰𝗼𝗻𝘁𝗮𝗶𝗻𝗲𝗿.

When /message is called, the controller gets its dependency injected from the container. No tight coupling. Easy to test. Clean architecture. 💪

💬 𝗛𝗮𝘃𝗲 𝘆𝗼𝘂 𝗶𝗺𝗽𝗹𝗲𝗺𝗲𝗻𝘁𝗲𝗱 𝗺𝘂𝗹𝘁𝗶𝗽𝗹𝗲 𝘀𝗲𝗿𝘃𝗶𝗰𝗲 𝗶𝗺𝗽𝗹𝗲𝗺𝗲𝗻𝘁𝗮𝘁𝗶𝗼𝗻𝘀 𝗼𝗿 𝘂𝘀𝗲𝗱 𝗺𝗼𝗰𝗸 𝘀𝗲𝗿𝘃𝗶𝗰𝗲𝘀 𝗳𝗼𝗿 𝘁𝗲𝘀𝘁𝗶𝗻𝗴 𝘄𝗶𝘁𝗵 𝗗𝗜 𝗶𝗻 𝘆𝗼𝘂𝗿 𝗽𝗿𝗼𝗷𝗲𝗰𝘁? 𝗪𝗼𝘂𝗹𝗱 𝗹𝗼𝘃𝗲 𝘁𝗼 𝗵𝗲𝗮𝗿 𝗵𝗼𝘄 𝘆𝗼𝘂 𝘀𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗲𝗱 𝗶𝘁! 👇