Why can't my xamarin app recieve data from my API call? - api

Question

Im new to connecting an API to my xamarin app.
When I try to call the API visual studio & the app do not give a response.
Visual studio keeps running but nothing happens.
I've changed the firewall settings, and set my IP adres in all the desired places. Still not luck.
If I go to my API using swager or postman and I just the same Uri as I want to pass trough with my app I get the correct response.
What could be the reason for this?
my code:
Material service:
private readonly string _baseUri;
public APIMaterialService()
{
_baseUri = "https://192.168.1.9:5001/api";
}
public async Task<Material> GetById(Guid id)
{
return await WebApiClient
.GetApiResult<Material>($"{_baseUri}/Materials/{id}");
}
WebApiClient:
public class WebApiClient
{
private static HttpClientHandler ClientHandler()
{
var httpClientHandler = new HttpClientHandler();
#if DEBUG
//allow connecting to untrusted certificates when running a DEBUG assembly
httpClientHandler.ServerCertificateCustomValidationCallback =
(message, cert, chain, errors) => { return true; };
#endif
return httpClientHandler;
}
private static JsonMediaTypeFormatter GetJsonFormatter()
{
var formatter = new JsonMediaTypeFormatter();
formatter.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
return formatter;
}
public async static Task<T> GetApiResult<T>(string uri)
{
using (HttpClient httpClient = new HttpClient(ClientHandler()))
{
//Gets stuck finding the response
string response = await httpClient.GetStringAsync(uri);
return JsonConvert.DeserializeObject<T>(response, GetJsonFormatter().SerializerSettings);
}
}
I'll also add some images of the postman and swager response:
This is the code fo my controller.
return OK (material) shows me the data retrieved from the API
public async Task<IActionResult> GetMaterialByPartOfMaterialNumberOP(string partOfMaterialNumber)
{
var material = await _materialService.GetMaterialListbyPartOfMaterialNumber(partOfMaterialNumber);
return Ok(material);
}

Answer 1

The symptom you have (stuck on result from calling a method of HttpClient class) suggests a deadlock.
I believe the deadlock happens if you create multiple instances of HttpClient.
Doc HttpClient Class says:
// HttpClient is intended to be instantiated once per application, rather than per-use. See Remarks.
And shows this code:
static readonly HttpClient client = new HttpClient();
HOWEVER a deadlock would only happen the SECOND time your code does new HttpClient. And using ... new HttpClient should protect you, at least in simple situations.
Here are ways there might be TWO HttpClients active:
Is it possible that GetApiResult gets called A SECOND TIME, before the first one finishes?
Does your app do new HttpClient ELSEWHERE?
Here is what the technique might look like in your app:
public class WebApiClient
{
static HttpClient _client = new HttpClient(ClientHandler());
public async static Task<T> GetApiResult<T>(string uri)
{
string response = await _client.GetStringAsync(uri);
return JsonConvert.DeserializeObject<T>(response, GetJsonFormatter().SerializerSettings);
}
}