passing variable number of multiple parameters in a HTTP Get request in C#

Question

I am trying to create a web API. As part of it I want to create a Get method which any accept any number of variable of a particular type.

public class MyController : ControllerBase
    {
        [HttpGet]
        public int[] Get(int[] ids)
        {

            for(int i = 0; i < ids.Length; i++)
            {
                ids[i] = ids[i] * 100;
            }

            return ids;
        }
    }

When I try to make a get request from postman using

https://localhost:44363/api/executionstatus?ids=1&ids=2&ids=3

I get an error

{"type":"https://tools.ietf.org/html/rfc7231#section-6.5.1","title":"One or more validation errors occurred.","status":400,"traceId":"|39f5d965-4240af31edd27f50.","errors":{"$":["The JSON value could not be converted to System.Int32[]. Path: $ | LineNumber: 0 | BytePositionInLine: 1."]}}

I have also tried with

https://localhost:44363/api/executionstatus?ids=1,2,3

but it is also resulting in the same error. What is the correct way to pass/handle multiple parameters from a get request?

Answer 1

I think if you explicitly mention you want to read the variable from the query string, it will work fine in the method you are describing:

//.net Core
public int[] Get([FromQuery]int[] ids)

//.net Framework
public int[] Get([FromUri]int[] ids)

The call:

https://localhost:44363/api/executionstatus?ids=1&ids=2&ids=3

Answer 2

Maybe you could try with string parameter

[HttpGet]
public int[] Get(string ids)
{
    var intIds = ids.Split(',').Select(int.Parse).ToList();
    for(int i = 0; i < intIds.Length; i++)
    {
        intIds[i] = intIds[i] * 100;
    }
    return intIds;
}

and call your api like this

https://localhost:44363/api/executionstatus?ids=1,2,3