Default return type in DOTNETCORE webapi

 Default return type in DOTNETCORE webapi

In ASP.NET Core Web API, the default return type for an action method is an `ActionResult<T>` where `T` is the type of data you want to return. `ActionResult<T>` is a flexible and powerful way to return data from your API because it allows you to return different HTTP status codes and handle various scenarios.

Here's how you can use `ActionResult<T>` in a typical ASP.NET Core Web API action method:

```csharp

[ApiController]

[Route("api/[controller]")]

public class ValuesController : ControllerBase

{

    [HttpGet("{id}")]

    public ActionResult<string> Get(int id)

    {

        // Simulated logic to get data based on the provided ID

        if (id > 0)

        {

            // Return 200 OK status code with a string value

            return Ok($"Value for ID {id}");

        }

        else

        {

            // Return 400 Bad Request status code with an error message

            return BadRequest("Invalid ID");

        }

    }

}

In this example, the `Get` action method returns an `ActionResult<string>`. Inside the method, you can use the `Ok()` method to return a 200 OK status code along with the string value. Similarly, you can use other methods like `BadRequest()`, `NotFound()`, `CreatedAtAction()`, etc., to return different HTTP status codes.

If you don't specify a return type explicitly, ASP.NET Core Web API allows you to return the following types directly from action methods:

- **`Task<IActionResult>`:** For asynchronous action methods that return different types of `ActionResult` based on logic.

- **`ActionResult`:** When you need to return a specific HTTP status code without a response body.

- **`ObjectResult`:** When you need to return a specific HTTP status code along with an object (e.g., a custom DTO).

- **`ActionResult<T>`:** When you want to return a specific HTTP status code along with a strongly typed object (`T`).

You can choose the appropriate return type based on your API's requirements and the desired behavior for different scenarios.