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?

Does this answer your question? [Pass an array of integers to ASP.NET Web API?](https://stackoverflow.com/questions/9981330/pass-an-array-of-integers-to-asp-net-web-api) — Jawad, Jul 21 '20 at 15:56

Stefan · Answer 1 · 2020-07-21T17:28:24.650

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

edited Jul 21 '20 at 17:28

answered Jul 21 '20 at 15:30

Stefan

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Can you try the object wrapper? Because that's how it's normally done. It allows a bit more freedom and flexibility for "complex" types. If it doesn't work I must have a typo somewhere. – Stefan Jul 21 '20 at 15:38
Btw, I'll try to spinup a quick project to test the first method – Stefan Jul 21 '20 at 15:39
@cvg: Cool, I hope it's sufficient for your case. I am now struggling myself on how to get that first one working XD – Stefan Jul 21 '20 at 15:48
1

@cvg: I think I got it - but I am using .net core. Behavior is similar, but not identical – Stefan Jul 21 '20 at 15:54
thanks @Stefan. I'm using .net core. using object wrapper I don't get error msgs. but the ids of data object being passed to the Get method is `null` – chink Jul 21 '20 at 16:15
@cvg: sorry: I have a typo - locally I used `test` where you used `ids` - i'll correct it - the name must match – Stefan Jul 21 '20 at 16:20
yes, I realised that test was typo and corrected at my end, but I see the ids as null using the latter approach by wrapping the data in an object – chink Jul 21 '20 at 16:25
oh... I believe you'll need to add the `[FromQuery]` there as well... sorry, I seem to be a bit rusty XD – Stefan Jul 21 '20 at 16:29

score 1 · Answer 2 · answered Jul 21 '20 at 17:56

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

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

2 Answers2