Web API Post giving me error - asp.net

Question

I have a web API application. I'm supposed to do a post to an endpoint. When l tried my API controller in postman, l get the error message "
Requested resource does not support HTTP 'POST'
I'm new to Web API so any help and suggestions are welcomed.
This is my model class:
namespace Products.Models
{
public class Prouct
{
public string ProductID { get; set; }
public string ProductName { get; set; }
public string ProductPrice { get; set; }
public string VoucherID { get; set; }
}
}
Here is my controller class
[RoutePrefix("api/products")]
public class ProductsController : ApiController
{
static HttpClient client = new HttpClient();
public IEnumerable<string> Get()
{
return new string[] { "value1", "value2" };
}
public string Get(int id)
{
return "value";
}
[Route("products")]
public async Task PostAsync(string ProductID, string ProductName, string ProductPrice,
string VoucherID)
{
Products p = new Products();
p.ProductID = ProductID;
p.ProductName = ProductName;
p.ProductPrice = ProductPrice;
p.VoucherID = VoucherID;
var client = new HttpClient { BaseAddress = new
Uri("http://localhost:51613/") };
var response = await
client.PostAsJsonAsync("api/products",
p);
if (response.IsSuccessStatusCode)
{
}
public void Put(int id, [FromBody]string value)
{
}
public void Delete(int id)
{
}

Answer 1

You need to specify HttpPost on PostAsync method. by default, it is [HttpGet].
[HttpPost]
[Route("products")]
public async Task PostAsync(string ProductID, string ProductName, string ProductPrice, string VoucherID)
{
// implementation
}

Answer 2

Looks like you're stuck in a loop. Why does the PostAsync method call itself after having been invoked? This will result in an endless request loop.
var client = new HttpClient { BaseAddress = new Uri("http://localhost:51613/") };
This is not related to the fact that the [HttpPost] attribute is required however.

Answer 3

Please observe that you are supposed to use [FromBody] . Also inside Postman (image attached) you have to choose "Raw" data with the product json with type as JSON(application.json).
[HttpPost]
[Route("products")]
public async Task PostAsync([FromBody] Products p)
{
var client = new HttpClient
{
BaseAddress = new
Uri("http://localhost:51613/")
};
var response = await
client.PostAsJsonAsync("api/products",
p);
if (response.IsSuccessStatusCode)
{
}
}