I am trying to execute a function on background when my app will open, to do this, I am trying to create an async function with task but I cannot do it works.
How do I to fix it ?
Xamarin OnStart
protected override void OnStart(){
DefineConcursoSession();
}
//execute in background
private async void DefineConcursoSession(){
ConcursoDTO dto = await ConcursoService.GetConcursoAtivo();
//save session
}
HttpClient
public async static Task<ConcursoDTO> GetConcursoAtivo(){
String ENDPOINT = "/GetConcursoAtivo";
String URL_FINAL = URL_CONTROLLER + ENDPOINT;
ConcursoDTO dto = new ConcursoDTO();
try
{
HttpClient hClient = new HttpClient();
hClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
hClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", BasicAuth.getHash());
//get
HttpResponseMessage response = hClient.GetAsync(URL_FINAL).GetAwaiter().GetResult();
var resultContent = response.Content.ReadAsStringAsync().GetAwaiter().GetResult();
//Console.WriteLine("Content: " + resultContent);
if (response.StatusCode == HttpStatusCode.OK){
JObject jo = JObject.Parse(resultContent);
dto = JsonConvert.DeserializeObject<ConcursoDTO>(jo["Concurso"].ToString());
}
}
catch (Exception e)
{
Debug.WriteLine("Erro: GetConcursoAtivo:-> " + e.Message);
}
return dto;
}
Related
I am using the HttpClient but my results are taking up to 6 seconds coming back from the same machine on the same subnet and ip range of 192.168. When I call the api directly from the ip address the results are more or less instant so why is it so slow with httpclient on the same computer.
I have seen other so's that suggest set to use proxy as false is the best way to go.
I have also tested this on a stock phone and it takes around 8 seconds for the login to be successful on the phone.
private HttpClient _client;
public async Task<String> Getusers()
{
var content = "";
HttpClientHandler hch = new HttpClientHandler();
hch.Proxy = null;
hch.UseProxy = false;
_client = new HttpClient(hch);
var uri = new Uri(Constants.ApiEndPoint + "/Users"); // Your url is here
try
{
var response = await _client.GetAsync(uri);
if (response.IsSuccessStatusCode)
{
content = await response.Content.ReadAsStringAsync();
}
}
catch (Exception ex)
{
throw ex;
}
return content;
}
Here is my login method in case anyone can see something wrong with it.
private async void BtnLogin_Clicked(object sender, EventArgs e)
{
string content = await Getusers(); //Sends a GET request to the specified Uri and returns the response body as a string in an asynchronous operation
List<Users> _users = JsonConvert.DeserializeObject<List<Users>>(content); //Deserializes or converts JSON String into a collection of Post
var userName = txtUserName.Text;
var password = txtPassword.Text;
var isValidUser = _users.Where(w => w.UserName == userName && w.password == password).FirstOrDefault();
var driverId = _users.Where(w => w.UserName == userName && w.password == password).FirstOrDefault().ID;
if (isValidUser != null)
{
Application.Current.Properties["driverId"] = driverId;
Application.Current.MainPage = new MainPage();
}
else
{
lblError.Text = "Error your credentials are invalid, please try again";
}
}
I'm trying to fetch records from a db cursor from the Client app.
Debugging Web API shows that the Cursor returns records but when returning to the Client it throws mscorlib.pdb not loaded window and clicking on Load option it throws TaskContinuation.cs not found exception
Code snippets as below ( removed irrelevant codes for readability )
WebAPI
[HttpPost("{values}")]
public async Task<ActionResult> Post([FromBody] JToken values)
{
// code removed for readility
string[] cursors = { };
cursors = await cursor.GetRpts();
CursorClass firstCursor = JsonConvert.DeserializeObject<CursorClass>(cursors[0]);
return new OkObjectResult(cursors);
}
public async Task<string[]> GetRpts()
{
try
{
DataTable[] dataTables;
CursorClass[] cursorClasses = new CursorClass[5];
//stripped some code
using (DataAccess dataAccess = new DataAccess()
{
ParamData = PrepareDoc(),
ProcedureName = Constants.Rpt,
RecordSets = this.CursorNumbers,
})
{
Int32 errorNumber = await dataAccess.RunComAsync();
dataTables = dataAccess.TableData;
};
//fetching code stripped off
string[] _cursors = Array.ConvertAll(cursorClasses, JsonConvert.SerializeObject);
return _cursors;
}
catch (Exception ex)
{
string tt = ex.Message;
}
}
public async Task<Int32> RunComAsync()
{
Int32 returnValue = 0;
try
{
//open db connection
//---------- Running the Command in asysnc mode ----------
Task<int> task = new Task<int>(oracleCommand.ExecuteNonQuery);
task.Start();
returnValue = await task;
//--------------------------------------------------------
OracleRefCursor[] refCursor = { null, null, null, null, null };
for (int _sub = 0; _sub < RecordSets; _sub++)
{
//DT declaration / connection code removed
dataAdapter.Fill(dataTable, refCursor[_sub]);
TableData[_sub] = dataTable;
}
}
catch (Exception ex)
{
return LogMsg(ex);
}
finally
{
this.Dispose(true);
}
CloseConnection();
return LogMsg(null,"Successful Operation");
}
Client
private async Task<HttpStatusCode> CallService()
{
HttpResponseMessage _response = null;
try
{
using (HttpRequestMessage requestMessage = new HttpRequestMessage()
{
Content = new System.Net.Http.StringContent(JsonRepo, System.Text.Encoding.UTF8, HeaderJson),
RequestUri = new Uri(UriString),
Method = HttpMethod.Post,
})
{
requestMessage.Headers.Authorization = new AuthenticationHeaderValue("Bearer", Utils.TOKEN) ;
_response = await httpClient.SendAsync(requestMessage);
if (_response.IsSuccessStatusCode)
{
string httpResponse = await _response.Content.ReadAsStringAsync();
httpString = JsonConvert.DeserializeObject<string[]>(httpResponse);
}
}
}
return ErrorCode;
}
Is that something related to async operation? while debugging the API it confirms the Datatable with records . Any inputs are deeply appreciated.
error image
TIA
I am developeing a chatbot using microsoftbotframmwok where I have some requirement to make a call from my task to an api(httpclient). but it is not working. when i test the api from an stand alone console application in side main method it works. but in my application it doesn't work.
I tried to call an api from an simple method without task but when it makes a cal its basically halts or stucked somewhere, i converted my function into task and while making an api call i used await keyword to call it asynchronously but it is returning error, while reading it not the result.
here is the my code which make an api call
private async Task<String> getProblem(IDialogContext context)
{
var response = "Thannks for contacting..";
//here some code logix..
SnowApiClient client = new SnowApiClient(Url, UserId, ApiPassword);
IncidentRequestPayload payload = new IncidentRequestPayload();
payload.caller_id = "tet111";
payload.assignment_group = "it";
payload.category = "complaint";
payload.u_feedback_type = "Praise";
payload.service_offering = "Application Management";
payload.priority = 2;
payload.short_description = "computer battery is dead";
payload.comments = String.Empty;
ApiResponse objResponse = await client.CreateIncident(payload);
//objResponse.payload.number;
return response;
}
//code for CreateIncident...in Api project librarary
public async Task<ApiResponse> CreateIncident(IncidentRequestPayload payload)
{
var incidentRequest = new ApiRequest { method = CreateIncidentMethod, payload = payload };
var createResult = await ExecuteRequest(incidentRequest);
return await ReadIncident(createResult.payload.incNumber);
}
public async Task<ApiResponse> ReadIncident(string number)
{
var incidentRequest = new ApiRequest { method = ReadIncidentMethod, payload = new RequestPayload { number = number } };
return await ExecuteRequest(incidentRequest);
}
private async Task<ApiResponse> ExecuteRequest(ApiRequest requestObject)
{
HttpResponseMessage response = await _client.PostAsJsonAsync("/SRintegratedAPI.rest", requestObject);
ApiResponse responseObject = null;
if (response.IsSuccessStatusCode)
{
responseObject = await response.Content.ReadAsAsync<ApiResponse>();
}
else
{
throw new System.Net.WebException(response.ReasonPhrase);
}
if (responseObject.result != "ok")
{
throw new System.Net.WebException(responseObject.message);
}
return responseObject;
}
I don't understand how and where do i used async/await here in basicalaly in my getProblem function.
please help
Since I am new to Xamarin, I would really appreciate if someone could explain me how to consume RESTful service (returning JSON data) using Xamarin Forms with the simplest example.
You can use JSON.net and HTTP request, here is a quick example of how to use the movie database which is a free movie database GET and POST examples, hope this helps:
const string _baseUrl = "http://api.themoviedb.org/3/";
const string _pageString = "&page=";
//GET Example
public static async Task<ObservableCollection<Movie>> GetTopRatedMoviesAsync(int page = 1)
{
HttpClient client = new HttpClient();
//_apiKey = themoviedb api key, page = page size 1 = first 20 movies;
string topRatedUrl = _baseUrl + "movie/top_rated?" + _apiKey + _pageString + page;
HttpResponseMessage result = await client.GetAsync (topRatedUrl, CancellationToken.None);
if (result.IsSuccessStatusCode) {
try{
string content = await result.Content.ReadAsStringAsync ();
ObservableCollection<Movie> MovieList = GetJsonData(content);
//return a ObservableCollection to fill a list of top rated movies
return MovieList;
}catch(Exception ex){
//Model Error
Console.WriteLine (ex);
return null;
}
}
//Server Error or no internet connection.
return null;
}
static ObservableCollection<Movie> GetJsonData(string content){
JObject jresponse = JObject.Parse (content);
var jarray = jresponse ["results"];
ObservableCollection<Movie> movieList = new ObservableCollection<Movie> ();
foreach (var jObj in jarray) {
Movie newMovie = new Movie();
newMovie.Title = (string)jObj["title"];
newMovie.PosterPath = _baseImgUrl + (string)jObj["poster_path"];
newMovie.HighResPosterPath = _baseImgUrl + (string)jObj["poster_path"];
newMovie.Id = (int)jObj["id"];
newMovie.Overview = (string)jObj["overview"];
newMovie.VoteCount = (double)jObj["vote_count"];
newMovie.ReleaseDate = (DateTime)jObj["release_date"];
newMovie.VoteAverage = (float)jObj["vote_average"];
movieList.Add(newMovie);
}
return movieList;
}
//POST Example:
public static async Task<bool> PostFavoriteMovieAsync(Movie movie)
{
try
{
HttpClient client = new HttpClient();
//_sessionId = string with the movie database session.
string tokenUrl = _baseUrl + "account/id/favorite?" + _apiKey + _sessionId;
string postBody = JsonConvert.SerializeObject(new Favorite{
favorite = !movie.Favorite,
media_id = movie.Id,
});
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = await client.PostAsync (tokenUrl,
new StringContent (postBody, Encoding.UTF8, "application/json"));
if(response.IsSuccessStatusCode)
return true;
else
return false;
}
catch(Exception ex){
Console.WriteLine (ex.Message);
return false;
}
}
I m trying to use http request webservice issue is that when we post wrong username and password the login service generate exception and it can't return any value in async calls.
A code snippet would help assist with the problem ...
However using a try catch should help you catch your exception and prevent application from crashing and handling the exceptions accordingly.
As seen in my sample code below I cater for the incorrect details entered / connectivity problems. I peform the http async request then parse the xml to my model handling the exceptions accordingly
var response = await WebRequestHelper.MakeAsyncRequest(url, content);
if (response.IsSuccessStatusCode == true)
{
Debug.WriteLine("Login Successfull" + "result.IsSuccessStatusCode" + response.IsSuccessStatusCode);
var result = response.Content.ReadAsStringAsync().Result;
result = result.Replace("<xml>", "<LoginResult>").Replace("</xml>", "</LoginResult>");
loginResult = XMLHelper.FromXml<LoginResult>(result);
if (loginResult != null)
{
login.Type = ResultType.OK;
login.Result = loginResult;
}
else
{
login.Type = ResultType.WrongDetails;
}
}
else
{
Debug.WriteLine("Login Failed" + "result.IsSuccessStatusCode" + response.IsSuccessStatusCode);
login.Type = ResultType.WrongDetails;
}
}
catch (Exception ex)
{
login.Type = ResultType.ConnectivityProblem;
}
Web Request
public static async Task<HttpResponseMessage> MakeAsyncRequest(string url, Dictionary<string, string> content)
{
var httpClient = new HttpClient();
httpClient.Timeout = new TimeSpan(0, 5, 0);
httpClient.BaseAddress = new Uri(url);
httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type: application/x-www-form-urlencoded", "application/json");
if (content == null)
{
content = new Dictionary<string, string>();
}
var encodedContent = new FormUrlEncodedContent(content);
var result = await httpClient.PostAsync(httpClient.BaseAddress, encodedContent);
return result;
I would recommend wrapping the response in a generic ServiceResponse where you can store the exceptions. await methods can be included in try/catch blocks so the standard process can be followed.
E.G.
public async Task<ServiceResponse<T>> PostAsync<T>(String address, object dto){
var content = Serializer.SerializeObject (dto);
var response = await client.PostAsync (
address,
new StringContent (content));
if (response.IsSuccessStatusCode) {
try {
var responseString = await response.Content.ReadAsStringAsync ();
return new ServiceResponse<T> (Serializer.DeserializeObject<T> (responseString),
response.StatusCode);
} catch (Exception ex) {
return new ServiceResponse<T> (response.StatusCode, ex);
}
} else {
return new ServiceResponse<T> (response.StatusCode);
}
}
With the ServiceResponse defined as :
public class ServiceResponse<T>
{
public HttpStatusCode StatusCode { get; set;}
public T Value { get; set;}
public String Content { get; set;}
public Exception Error {get;set;}
public ServiceResponse(T value, HttpStatusCode httpStatusCode){
this.Value = value;
this.StatusCode = httpStatusCode;
}
public ServiceResponse(HttpStatusCode httpStatusCode, Exception error = null){
this.StatusCode = httpStatusCode;
this.Error = error;
}
}
This will give you a clean way of managing all your HTTP responses and any errors that may occur.