I am learning Windows Phone 8.1 development, I have probably done something utterly incorrectly programming wise
The need: I want to download a text file from the web using HttpClient() and display it in the TextBlock1
From variety of tutorials I have found the following:
public async void DownloadDataAsync()
{
string data = "some link to Textfile.txt";
HttpClient client = new HttpClient();
HttpResponseMessage response = await client.GetAsync(data);
HttpContent content = response.Content;
string result = await content.ReadAsStringAsync();
UpdateTextBlock1(result);
}
Then the other functions.
public void UpdateTextBlock1(string result)
{
TextBlock1.Text = result;
}
private void BtnDownloadData_Click(object sender, RoutedEventArgs e)
{
Task t = new Task(DownloadDataAsync);
t.Start();
}
The code starts well enough - on button pressed, I receive RPC_E_WRONG_THREAD.
Is it that I'm trying to call the method when all threads haven't finished? How can I code that efficently so the TextBlock1 is updated with txt data?
Thanks for understanding, baby steps here in programming, and I couldn't find a relevant answer over google. (Maybe I don't yet know how to ask?)
You need to update the textblock on the UI thread like so:
Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
{
TextBlock1.Text = result;
});
There are many posts on this subject.
Related
If i run this code on console application:
static async Task Main(string[] _)
{
using var client = new WTelegram.Client();
var user = await client.LoginUserIfNeeded();
Console.WriteLine($"We are logged-in as {user.username ?? user.first_name + " " + user.last_name} (id {user.id})");
}
It will prompt interactively for App api_id and api_hash.
How can i Authorize user on winforms application?. So that i can input the api_id and api_hash through textbox
Edit: (Oct 2022) Latest version of the library has a simplified config system that makes it more easy to use in WinForms apps.
Please take a look at the example WinForms app provided in the repository that demonstrate how to proceed.
The original answer below is still valid but maybe more complex
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
First, you should read WTelegramClient FAQ #3:
3. How to use the library in a WinForms or WPF application
The library should work without a problem in a GUI application.
The difficulty might be in your Config callback when the user must enter the verification code or password, as you can't use Console.ReadLine here.
An easy solution is to call Interaction.InputBox("Enter verification code") instead.
This might require adding a reference (and using) to the Microsoft.VisualBasic assembly.
A more complex solution requires the use of a ManualResetEventSlim that you will wait for in Config callback,
and when the user has provided the verification_code through your GUI, you "set" the event to release your Config callback so it can return the code.
Here is an example solution for your Form class with a ManualResetEventSlim and textboxes:
using Microsoft.VisualBasic;
using TL;
private readonly ManualResetEventSlim _codeReady = new ManualResetEventSlim();
private WTelegram.Client _client;
private User _user;
string Config(string what)
{
switch (what)
{
case "api_id": return textBoxApiID.Text;
case "api_hash": return textBoxApiHash.Text;
case "phone_number": return textBoxPhone.Text;
case "verification_code":
_codeReady.Reset();
_codeReady.Wait();
return textBoxCode.Text;
case "password": return Interaction.InputBox("Enter 2FA password");
default: return null;
};
}
private void textBoxCode_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == '\r') // pressing Return in the textboxCode
{
_codeReady.Set();
e.Handled = true;
}
}
private async void buttonLogin_Click(object sender, EventArgs e)
{
buttonLogin.Enabled = false;
_client = new WTelegram.Client(Config);
_user = await _client.LoginUserIfNeeded();
MessageBox.Show("We are now connected as " + _user);
}
private async void buttonGetChats_Click(object sender, EventArgs e)
{
if (_user == null) { MessageBox.Show("You must complete the login first."); return; }
var chats = await _client.Messages_GetAllChats(null);
MessageBox.Show(string.Join("\n", chats.chats.Values.Where(c => c.IsActive)));
}
I am trying to parse some pois from a xml download from a server and I saw that it is done after the program continues in the main thread. I haven't found a way to solve it because I need it.
using System.Threading;
namespace XML_Parser
{
class XMLParserPOI_Wiki
{
private static XMLParserPOI_Wiki objSingle = new XMLParserPOI_Wiki();
public static XMLParserPOI_Wiki ObjSingle
{
get { return objSingle; }
set { objSingle = value; }
}
private List<POI> places;
public List<POI> Places
{
get { return places; }
}
private XMLParserPOI_Wiki()
{
}
public void parseWikitude(string url)
{
places = new List<POI>();
WebClient wc = new WebClient();
wc.DownloadStringCompleted += HttpsCompleted;
wc.DownloadStringAsync(new Uri(url));
}
private void HttpsCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error == null)
{
XDocument xdoc = XDocument.Parse(e.Result, LoadOptions.None);
XNamespace ns = "http://www.opengis.net/kml/2.2";
XNamespace ns2 = "http://www.openarml.org/wikitude/1.0";
var placemarkers = xdoc.Root.Descendants(ns + "Placemark");
places =
(from query in xdoc.Root.Descendants(ns + "Placemark")
select new POI
(
...
)).ToList();
System.Diagnostics.Debug.WriteLine("Lista");
System.Diagnostics.Debug.WriteLine(places.Count);
}
}
}
}
In my main class:
XMLParserPOI_Wiki parserXML = XMLParserPOI_Wiki.ObjSingle;
parserXML.parseWikitude("http://myurl.php");
System.Diagnostics.Debug.WriteLine("Lista de pois");
System.Diagnostics.Debug.WriteLine(parserXML.Places.Count);
for (int i = 0; i < parserXML.Places.Count; i++)
{
System.Diagnostics.Debug.WriteLine(parserXML.Places[i].getName());
}
It prints Lista de POis and 0, before Lista and X (number of pois)
I guess I should freeze main thread but I tried a couple of times with some examples and they didn't work.
Can you point me to any tutorial about this? More than get an answer I want to understand how to deal with this kind of operations
First of all, you don't want to block (freeze) the UI thread EVER!
This is called asynchronous programming. There are two things you can do to solve your problem (I recommend option 2!):
Use the classic callback model. You basically call some long operation on a background thread and give a function to it, to execute when the long operation is done. Here's how to do it in your case.
At the end of the HttpsCompleted method, invoke what you need on the UI Thread using:
Deployment.Current.Dispatcher.BeginInvoke(delegate() {
//The code here will be invoked on the UI thread
});
If you want to make the parseWikitude method reusable, you should pass an Action to it. This way you can call it from multiple places and tell it what to do on the UI thread when the parsing is done. Something like this:
public void parseWikitude(string url, Action callback) {
places = new List<POI>();
WebClient wc = new WebClient();
wc.DownloadStringCompleted += HttpsCompleted;
wc.DownloadStringAsync(new Uri(url), callback);
}
private void HttpsCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error == null)
{
...
var callback = (Action)e.UserState;
Deployment.Current.Dispatcher.BeginInvoke(callback);
}
}
//And then when you use it, you do it like that
parserXML.parseWikitude("http://myurl.php", delegate() {
//The code here will be executed on the UI thread, after the parsing is done
});
Use the (rather) new asnyc pattern in .NET. You should read about this, as it is one of the best features of .NET if you ask me. :) It basically does the callback thing automatically and makes the code a lot easier to read/maintain/work-with. Once you get used to it, that is.
Here's an example:
public Task<List<POI>> parseWikitude(string url) {
TaskCompletionSource<List<POI>> resultTaskSource = new TaskCompletionSource<List<POI>>();
WebClient wc = new WebClient();
wc.DownloadStringCompleted += HttpsCompleted;
wc.DownloadStringAsync(new Uri(url), resultTaskSource);
return resultTaskSource.Task;
}
private void HttpsCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error == null)
{
//If needed, run the code here in a background thread
//...
var resultTaskSource = (TaskCompletionSource<List<POI>>)e.UserState;
resultTaskSource.SetResult(places);
}
}
//And when you need to use it, do it like that (note, this must be invoked in an async method!)
var places = await parser.parseWikitude("http://myurl.php");
//The code here will be executed on the same thread when the parsing is done, but the thread will not be blocked while the download is happening.
So, these are the two ways you can handle it. Option one is old-school, classic and easy. Option two is the new and cool way of doing async stuff. It really is a must-know. Simplifies a lot of things once you get used to it.
P.S. Sorry if I got carried away. :D
I just wrote a simple windows 8 form that post to web service api. It works fine. But my challenge is been able to determine when the post operation was a success and a failure. I dont know how to return a value cos aysnc Task is not allowing a return type.
//This class does the post to web service
public class B2cMobileuserService : IB2cMobileuserService
{
private string RegisterUserUrl = RestfulUrl.RegisterMobileUser;
private readonly HttpClient _client = new HttpClient();
public async Task RegisterMobileUser(B2cMobileuserView user)
{
var jsonString = Serialize(user);
var content = new StringContent(jsonString, Encoding.UTF8, "application/json");
var result = await _client.PostAsync(RegisterUserUrl, content);
}
}
//This class calls the one above
public class WebserviceProcessor
{
//declaring all the service objects that would be used
IB2cMobileuserService mobileuserService = null;
public WebserviceProcessor() {
mobileuserService = new B2cMobileuserService();
}
//This method is going to post values to the web serever
public async void RegisterUser(B2cMobileuserView mobileuser) {
mobileuserService.RegisterMobileUser(mobileuser);
}
}
//Then the code below is from my .xaml user interface that calls the class that sends to webservice
private void Button_Click(object sender, RoutedEventArgs e)
{
B2cMobileuserView user = new B2cMobileuserView();
user.Name = name.Text;
user.Email = email.Text;
user.PhoneType = "Windows Mobile";
user.BrowserType = "None";
user.CountryName = "Nigeria";
user.UserPhoneID = phone.Text;
Serviceprocessor.RegisterUser(user);
progressBar.Visibility = Visibility.Visible;
}
Please I dont know how to return a value cos when I try I get the error that says async method must be void.
I need to set a way to know when the post was a success based on the return value from the web service.
To ensure the POST was successful, call HttpResponseMessage.EnsureSuccessStatusCode:
public async Task RegisterMobileUser(B2cMobileuserView user)
{
var jsonString = Serialize(user);
var content = new StringContent(jsonString, Encoding.UTF8, "application/json");
var result = await _client.PostAsync(RegisterUserUrl, content);
result.EnsureSuccessStatusCode();
}
If you want to return a value, use a Task<T> return type instead of Task.
On a side note, avoid async void; use async Task instead of async void unless the compiler forces you to write async void:
//This method is going to post values to the web serever
public Task RegisterUser(B2cMobileuserView mobileuser) {
return mobileuserService.RegisterMobileUser(mobileuser);
}
Also, you should name your asynchronous methods ending in *Async:
//This method is going to post values to the web serever
public Task RegisterUserAsync(B2cMobileuserView mobileuser) {
return mobileuserService.RegisterMobileUserAsync(mobileuser);
}
You may find my async intro and MSDN article on async best practices helpful.
I have a list of theaters and I created a secondary tile from my application to navigate directly to specific theater. I pass the id of the theater in query string :
I load the theaters from a WCF service in the file "MainViewModel.cs"
In my home page, I have a list of theaters and I can navigate to a details page.
But when I want to navigate from the tile, I have an error...
The Tile :
ShellTile.Create(new Uri("/TheaterDetails.xaml?selectedItem=" + theater.idTheater, UriKind.Relative), tile, false);
My TheaterDetails page :
public partial class TheaterDetails : PhoneApplicationPage
{
theater theater = new theater();
public TheaterDetails()
{
InitializeComponent();
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
if (!App.ViewModel.IsDataLoaded)
{
App.ViewModel.LoadData();
}
if (DataContext == null)
{
string selectedIndex = "";
if (NavigationContext.QueryString.TryGetValue("selectedItem", out selectedIndex))
{
int index = int.Parse(selectedIndex);
theater = (from t in App.ViewModel.Theaters
where t.idTheater == index
select t).SingleOrDefault();
DataContext = theater;
....
....
....
The error :
https://dl.dropboxusercontent.com/u/9197067/error.png
Like if the data were not loaded...
Do you have an idea where the problem come from ?
The solution could be easy but I am a beginner... Maybe it's because I load the data asynchronously and the application doesn't wait until it's done...
Thanks
EDIT :
My LoadData() method :
public void LoadData()
{
client.GetTheatersCompleted += new EventHandler<ServiceReference1.GetTheatersCompletedEventArgs>(client_GetTheatersCompleted);
client.GetTheatersAsync();
// Other get methods...
this.IsDataLoaded = true;
}
private void client_GetTheatersCompleted(object sender, ServiceReference1.GetTheatersCompletedEventArgs e)
{
Theaters = e.Result;
}
You should check to see which variable is actually null. In this case it looks to be Theaters (otherwise the error would have thrown earlier).
Since Theaters is populated from a web call it is most likely being called asynchronously, in other words when you return from LoadData() the data is not yet there (it's still waiting for the web call to come back), and is waiting for the web service to return its values.
Possible solutions:
Make LoadData() an async function and then use await LoadData(). This might require a bit of rewriting / refactoring to fit into the async pattern (general introduction to async here, and specific to web calls on Windows Phone here)
A neat way of doing this that doesn't involve hacks (like looping until the data is there) is to raise a custom event when the data is actually populated and then do your Tile navigation processing in that event. There's a basic example here.
So the solution that I found, thanks to Servy in this post : Using async/await with void method
I managed to use async/await to load the data.
I replaced my LoadData() method by :
public static Task<ObservableCollection<theater>> WhenGetTheaters(ServiceClient client)
{
var tcs = new TaskCompletionSource<ObservableCollection<theater>>();
EventHandler<ServiceReference1.GetTheatersCompletedEventArgs> handler = null;
handler = (obj, args) =>
{
tcs.SetResult(args.Result);
client.GetTheatersCompleted -= handler;
};
client.GetTheatersCompleted += handler;
client.GetTheatersAsync();
return tcs.Task;
}
public async Task LoadData()
{
var theatersTask = WhenGetTheaters(client);
Theaters = await theatersTask;
IsDataLoaded = true;
}
And in my page :
protected override async void OnNavigatedTo(NavigationEventArgs e)
{
if (!App.ViewModel.IsDataLoaded)
{
await App.ViewModel.LoadData();
}
I dont think this is working, I was wondering if you could spot anything wrong with my code and how I could fix it please? Im new very to this and not sure whether to use web request, web response or anything. Whats the most basic way of doing POST to json?
Thank you
private void btnSaveCar_Click(object sender, RoutedEventArgs e)
{
string url = "http://......";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "POST";
request.BeginGetRequestStream(new AsyncCallback(ProcessResponse), request);
}
private void ProcessResponse(IAsyncResult asyncResult)
{
HttpWebRequest request = (HttpWebRequest)asyncResult.AsyncState;
Stream streamResp = request.EndGetRequestStream(asyncResult);
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(Car));
Car newCar = new Car():
Deployment.Current.Dispatcher.BeginInvoke(() =>
{
newCar.Condition = txtCondition.Text;
newCar.Colour = txtColour.Text;
newCar.RegistrationNumber = txtReg.Text;
newCar.Model = txtModel.Text;
short.TryParse(txtYear.Text, out newCar.Year);
short chassisNumber;
short.TryParse(txtChassisNumber.Text, out chassisNumber);
newCar.ChassisNumber = chassisNumber;
newCar.BodyStyle = txtBodyStyle.Text;
try
{
ser.WriteObject(streamResp, newCar);
NavigationService.GoBack();
}
catch
{
MessageBox.Show("didnt work :(");
}
});
}
Your code is incomplete, you should call the Request.BeginGetResponse() method after writing the data to the Request stream!
Look at this sample code on how to do a POST with WebRequest (do take notice that the sample is for .NET 4.0 but I think you'll get the idea).
I'd still suggest that you use RestSharp instead of going with the basic WebRequest to save some development time!