Asp.net core Cleanest way to return View or Json/XML

Question

In asp.net core I would like to set up my API controller to do the following:

by default return View(model);

/api/id.json to return model; as json

/api/id.xml to return model; as xml

The second two can be achieved by using the [FormatFilter] see here

[FormatFilter]
public class ProductsController
{
    [Route("[controller]/[action]/{id}.{format?}")]
    public Product GetById(int id)

However this requires the method to return an object and not a View(object). Is there anyway to cleanly support also returning Views?

Answer 1

You cannot do both in the same action. However, you can factor out the common functionality into a private method and then implement two actions with minimal code duplication:

[Route("[controller]")]
[FormatFilter]
public class ProductsController : Controller
{
    private Product GetByIdCore(int id)
    {
        // common code here, return product
    }

    [HttpGet("[action]/{id}")]
    [ActionName("GetById")]
    public IActionResult GetByIdView(int id) => View(GetByIdCore(id));

    [HttpGet("[action]/{id}.{format}")]
    public Product GetById(int id) => GetByIdCore(id);
}

It's necessary to use different action names here, because the method signatures cannot differ merely on return type. However, the [ActionName] attribute can be used as above to make them appear to have the same name for the purposes of URL generation and such.