Array in Api's Query String

Question

Using WebClient do send an array to an ApiController via query string I get the error 400.

The api method looks like

public IHttpActionResult List([FromUri] Model model)

In the Model class I have

public int[] Ids { get; set; }

In the client side the code looks like:

webClient.QueryString.Add("ids", "1");
webClient.QueryString.Add("ids", "2");
...
await webClient.DownloadStringTaskAsync(url);

If I send just one "ids" parameter the code works fine, but not with two or more.

I found that the client creates the url like "url?ids=1,2" instead "url?ids=1&ids=2".

Is there some configuration I missed?

I think the problem is that ASP.NET doesn't create GET strings with duplicate key names per default. You could try to manually generate a GET URL — Moray, Aug 14 '20 at 13:53
I'm using .Net 4.6, not Core. Yes @Moray but it's strange that Api don't work with WebClient in the same .Net version. If I create the query string by hand it works. — Max Bündchen, Aug 14 '20 at 13:55
I found that is required code this solution out of the box: https://stackoverflow.com/questions/9981330/pass-an-array-of-integers-to-asp-net-web-api — Max Bündchen, Aug 14 '20 at 13:57

score 1 · Answer 1 · answered Aug 14 '20 at 14:07

1

WebClient will automatically turn multiple values with the same key into a comma separated string. You can change this behavior, see: How to build WebClient querystring with duplicate keys?

I would recommend using HttpClient instead of WebClient though.

answered Aug 14 '20 at 14:07

Rudey

Completly agree with using `HttpClient` instead of the legacy `WebClient` – Tom el Safadi Aug 14 '20 at 14:08

1 Answers1