How can i get a single response using linq - json

Question

I have the following API code to get a single result response but i get error json.net complaining
when i remove this line var Product = prdList .FirstOrDefault(a => a.ID == productID); and return Json(prdList); it works fine but return every row in a table. how can i get a single record?
Here is the code
[HttpGet("{productID}")]
public async Task<IActionResult> Getproduct(int productID)
{
var prdList = (await rpsService.Getrps(productID)).ToList();
var Product = prdList .FirstOrDefault(a => a.ID == productID);
return Json(Product);
}
Here is the error im getting, i retrive the right information but i get error when i load the page
JsonSerializationException: Cannot deserialize the current JSON object
(e.g. {"name":"value"}) into type 'System.Collections.Generic.IList`1
Project name' because the type requires a JSON array (e.g. [1,2,3]) to
deserialize correctly. To fix this error either change the JSON to a
JSON array (e.g. [1,2,3]) or change the deserialized type so that it
is a normal .NET type (e.g. not a primitive type like integer, not a
collection type like an array or List) that can be deserialized
from a JSON object. JsonObjectAttribute can also be added to the type
to force it to deserialize from a JSON object. Path 'productID', line
1, position 13.
I tried this working fine but display all rows
[HttpGet("{productID}")]
public async Task<IActionResult> GetProduct(int productID)
{
var prdList = (await rpsService.Getrps(productID)).ToList();
return Json(prdList );
}

Answer 1

you can directly apply condition while fetching list as mention below.
var prdList = (await rpsService.Getrps(productID)).ToList().FirstOrDefault();

Answer 2

Try this
var Product = prdList.Where(a => a.ID == productID).FirstOrDefault();
or
var prdList = (await rpsService.Getrps(productID)).ToList().FirstOrDefault();
return Json(prdList);