# What is a Controller?
In the context of Web-Dev, a Controller is a component of the Model-View-Controller (MVC) pattern. Controllers are responsible for handling user input, processing it & updating the model/view accordingly.
A Controller acts as interface between the UI & application logic.
# Controller-Types
# Api Controllers
Are specialized type of controllers designed for building APIs.
They inherit from ControllerBase and are decorated with the [ApiController] attribute.
Api-Controllers handle HTTP requests & return data, that a client can consume.
# MVC Controllers
# Web API Controllers
# Dependency Injection
# Constructor Injection
When you create an instance of a class, we specify which other parts of our code it should use directly during its creation.
This information is provided through the constructor.
- constructor - (method called when you create a new instance of a class)
Here: an instance of IStudentRepository is injected
public class StudentController : ControllerBase
{
private IStudentRepository studentRepository;
public StudentController(IStudentRepository studentRepository)
{
this.studentRepository = studentRepository;
}
// Other action methods...
}In the Program.cs the Service is registered & a new object of StudentRepository is created for each HTTP request within a scope.
builder.Services.AddControllers();
builder.Services.AddScoped<IStudentRepository, StudentRepository>();
// maps controllers - to handle incoming HTTP requests
app.MapControllers();