Develop Reference

Is there a way to create a timeout to an attempt to connection with Xamarin.Forms?

I'm trying to develop a warning if I try to connect to a specific SSID and some waiting time has passed. I've tried with a Timer class but there is some issues with Task and Threads I can't resolve.
This is my Wifi class in Xamarin.Droid
public class Wifi : Iwifi
{
private Context context;
private static WifiManager _manager;
private MyReceiver _receiver;
public void Initialize()
{
context = Android.App.Application.Context;
_manager = (WifiManager)context.GetSystemService(Context.WifiService);
_receiver = new MyReceiver();
}
public void Register()
{
IntentFilter intents = new IntentFilter();
intents.AddAction(WifiManager.ScanResultAction);
intents.AddAction(WifiManager.NetworkStateChangedAction);
context.RegisterReceiver(_receiver, intents);
}
public void Unregister()
{
context.UnregisterReceiver(_receiver);
}
public void ScanWirelessDevices()
{
_manager.StartScan();
}
public string GetConnectionSSID()
{
return _manager.ConnectionInfo.SSID;
}
public void ConnectToSSID(string SSID, string pwd)
{
if (!_manager.IsWifiEnabled)
{
_manager.SetWifiEnabled(true);
}
WifiConfiguration wifiConfiguration = new WifiConfiguration();
wifiConfiguration.Ssid = '"' + SSID + '"';
if (pwd.Empty)
{
wifiConfiguration.AllowedKeyManagement.Set((int)KeyManagementType.None);
}
else
{
//Configuration for protected Network
}
var addNet = _manager.AddNetwork(wifiConfiguration);
if (addNet == -1)
{
_manager.Disconnect();
_manager.EnableNetwork(addNet, true);
_manager.Reconnect();
return;
}
var list = _manager.ConfiguredNetworks;
foreach (WifiConfiguration conf in list)
{
if (conf.Ssid.Equals('"' + SSID + '"'))
{
_manager.Disconnect();
_manager.EnableNetwork(conf.NetworkId, true);
_manager.Reconnect();
return;
}
}
}
public class MyReceiver : BroadcastReceiver
{
public override void OnReceive(Context context, Intent intent)
{
if (intent.Action.Equals(WifiManager.ScanResultAvailableAction))
{
IList<ScanResult> scanResult = _manager.ScanResult;
App.Networks.NetworksList.Clear();
foreach (ScanResult result in scanResult)
{
App.Networks.NetworksList.Add(result.Ssid);
}
}
}
}
}
Then this is a part of App class in Xamarin.Forms
public partial class App: Application
{
private static ...
.
.
.
private static string _selectedSSID;
private static MainDetail _pageDetail;
public static IWifi WifiManager { get; } = DependencyService.Get<Iwifi>();
public static string SelectedSSID { get { return _selectedSSID; } set { _selectedSSID = value; } }
public static MainDetail PageDetail { get { return _pageDetail; } }
public App()
{
InitializeComponent();
WifiManager.Initialize();
WifiManager.Register();
InitViews();
MainPage = _mainPage;
Connectivity.ConnectivityChanged += NetworkEvents;
NetSearch();
}
.
.
.
public void NetSearch()
{
Task.Run(async () =>
{
while (true)
{
WifiManager.ScanWirelessDevices();
await Task.Delay(Utility.SCAN_WIFI_TIMER); //waiting 31000 milliseconds because of Scanning throttling
}
});
}
public void NetworkEvents(object sender, ConnectivityChangedEventArgs e)
{
MainMaster master = (MainMaster)_mainPage.Master;
if (e.NetworkAccess == NetworkAccess.Unknown)
{
Debug.WriteLine("Network Access Unknown " + e.ToString());
}
if (e.NetworkAccess == NetworkAccess.None)
{
Debug.WriteLine("Network Access None " + e.ToString());
}
if (e.NetworkAccess == NetworkAccess.Local)
{
Debug.WriteLine("Network Access Local " + e.ToString());
}
if (e.NetworkAccess == NetworkAccess.Internet)
{
if(selectedSSID == Wifimanager.GetConnectionInfo())
{
//WE CONNECTED!!
//Now I want to stop the Timeout Timer to attempt
}
}
if (e.NetworkAccess == NetworkAccess.ConstrainedInternet)
{
Debug.WriteLine("Network Access Constrainde Internet " + e.ToString());
}
}
}
And part of Detail page class in which I start the event of connection and where I want to start also the timeout timer
public partial class MainDetail : ContentPage
{
.
.
.
public void OnItemListClicked(object sender, SelectedItemChangedEventArgs e)
{
if (e.SelectedItem == null)
{
return;
}
ImageCell item = (ImageCell)e.SelectedItem;
App.SelectedSSID = item.Text;
App.WifiManager.ConnectToSSID(item.Text, "");
ActivityIndicator(true);
//Now the timer should start.
//And call PageDetail.ActivityIndicator(false) and warning the user if the timeout go to 0.
listView.SelectedItem = null;
}
}
I tried with the Timers Timer class but doesn't work.. any suggestion?

Ok I figured a solution! Instead of using Thread and Task, I used Device.StartTimer.
In the event on the DetailPage I wrote:
public void OnItemListClicked(object sender, SelectedItemChangedEventArgs e)
{
if (e.SelectedItem == null)
{
return;
}
ImageCell item = (ImageCell)e.SelectedItem;
App.SelectedSSID = item.Text;
App.WifiManager.ConnectToSSID(item.Text, "");
ActivityIndicator(true);
Device.StartTimer(TimeSpan.FromSeconds(10), () => //Waiting 10 second then if we are not connected fire the event.
{
Device.BeginInvokeOnMainThread(() =>
{
if (App.IsLogout) //variable I use to check if I can do the logout or not
{
ActivityIndicator(false);
App.SelectedSSID = "";
//My message to users "Fail to connect"
}
});
return false;
});
listView.SelectedItem = null;
}

C# Form App - stop execution of all code from a helper method that resides in a helper class

I just learned how to pass arguments into methods, so I'm refactoring my code to make it cleaner. I have created a new "ValidateInput" class which holds a ValidateFinancialsInput method which I pass a string into. It then checks the string to see if it is correct, if it's not I want to show a messageBox, then stop execution of ALL of the code. If i use "return;", it just resumes execution of the Parent method. How do I stop execution of all of the code within the ValidateFinancialsInput method? I tried researching this for a while to no avail. Here is my code:
Class Parent
{
private void button2_Click(object sender, EventArgs e)
{ var CompanyVar = comboBox1.Text;
ValidateInput vi = new ValidateInput();
vi.ValidateFinancialsInput(CompanyVar);
//the rest of my code for the application is here
//the rest ...
//the rest...
}
}
class ValidateInput
{
public void ValidateFinancialsInput(string Co)
{
string[] validCompany = { "BVV", "LWDO" };
if (validCompany.Contains(Co) == false)
{
MessageBox.Show("You have entered an invalid company.");
//what do I put here to stop all code execution?
}
}
}

You should try and use return values state intent to calling methods
Class Parent
{
private void button2_Click(object sender, EventArgs e)
{ var CompanyVar = comboBox1.Text;
ValidateInput vi = new ValidateInput();
if(!vi.ValidateFinancialsInput(CompanyVar))
{
MessageBox.Show("You have entered an invalid company.");
return;
}
//the rest of my code for the application is here
//the rest ...
//the rest...
}
}
class ValidateInput
{
public bool ValidateFinancialsInput(string Co)
{
string[] validCompany = { "BVV", "LWDO" };
if (validCompany.Contains(Co) == false)
{
return false;
}
return true;
}
}
What I'm doing here is returning a true|false value to indicate whether the validation has passed, if it has not passed then I display the MessageBox, else it continues the execution of the "other" code.
Hope this helps

The simplest way is with an exception:
class Parent
{
private void button2_Click(object sender, EventArgs e)
{
try
{
var CompanyVar = comboBox1.Text;
ValidateInput vi = new ValidateInput();
vi.ValidateFinancialsInput(CompanyVar);
//the rest of my code for the application is here
//the rest ...
//the rest...
}
catch (ValidationException ex)
{
MessageBox.Show(ex.Message);
}
}
}
class ValidationException : Exception
{
public ValidationException(string message) : base(message)
{
}
}
class ValidateInput
{
public void ValidateFinancialsInput(string Co)
{
string[] validCompany = { "BVV", "LWDO" };
if (validCompany.Contains(Co) == false)
{
throw new ValidationException("You have entered an invalid company.");
}
}
}
This will stop execution of ValidateFinancialsInput and in button2_Click move execution inside the catch (ValidationException ex) where you can decide what to do with the validation error

You have a class that it's whole purpose is to validate, So you could add a public method IsValidated
You could add much more with the class, for example have a list of all business rules it violates and return them through another method or property.
class ValidateInput
{
public bool IsValidated {get; private set}
public bool ValidateFinancialsInput(string Co)
{
string[] validCompany = { "BVV", "LWDO" };
this.IsValidated = validCompany.Contains(Co)
}
}
This class should only know about the validation process and should do nothing else.

You have a few options. It looks like you have buttons in your program so I would guess this is not a console application. If you want the application to completely stop you can use Application.Exit or check out Environment.Exit https://msdn.microsoft.com/en-us/library/system.environment.exit(v=vs.110).aspx
However, I would suggest using exceptions so you do not terminate your entire program:
try
{
var CompanyVar = comboBox1.Text;
ValidateInput vi = new ValidateInput();
vi.ValidateFinancialsInput(CompanyVar);
//the rest of my code for the application is here
//the rest ...
//the rest...
}
catch (ValidationException ex)
{
MessageBox.Show(ex.Message);
}
}
public void ValidateFinancialsInput(string Co)
{
string[] validCompany = { "BVV", "LWDO" };
if (validCompany.Contains(Co) == false)
{
throw new ValidationException("You have entered an invalid company.");
}
}

Best way to pass data to a DataGridView form from another non-form class

As the title says, I need to pass a list of hashtables from a regular class to a form class to be rendered in a DataGridView. What I've got so far is this:
namespace somenamespace
{
class aldeloUpdater
{
private static string client = "chanchitos";
private static string establishment = "c1";
static void Main()
{
try
{
var guiForm = new GuiForm(); // Instantiating the Form-derived class.
string deliveriesListResp = getOrders();
Processing...
foreach (...)
{
if ((bool)DBresponse["status"])
{
guiForm.dataGridViewProducts = (List<Hashtable>)DBresponse["deliveriesSaved"]; // Passing the data to the DataGridView.
foreach (Hashtable delivery in (List<Hashtable>)DBresponse["deliveriesSaved"])
{
string updateDeliveryResponse = updatePedidoInDomicilios(delivery["domiciliosOrderId"].ToString(), 2, DBresponse["errmsg"].ToString());
}
}
else
{
Processing...
}
}
guiForm.ShowDialog(); // Showing the form.
More processing...
}
catch (Exception e)
{
Console.WriteLine("Exception details: " + e.ToString());
Console.ReadLine();
}
}
More methods...
}
Now the Form class looks like this:
namespace somenamespace
{
public partial class GuiForm : Form
{
public List<Hashtable> dataGridViewProducts; // Variable used to store the data to be rendered by the DataGridView.
public GuiForm()
{
InitializeComponent();
}
private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
}
private void GuiForm_Load(object sender, EventArgs e)
{
int index = 0;
foreach (Hashtable product in dataGridViewProducts)
{
dataGridView1.Rows.Add();
dataGridView1.Rows[index].Cells[0].Value = product["productName"];
dataGridView1.Rows[index].Cells[1].Value = product["userName"];
dataGridView1.Rows[index].Cells[2].Value = product["dateAndTime"];
dataGridView1.Rows[index].Cells[3].Value = product["domiciliosOrderId"];
index++;
}
}
Some more methods.
}
}
For now this code works just fine and the data is shown in the DataGridView, nonetheless I feel like there must be a better way to achieve this goal, it's just that I'm new to C#. I will appreciate suggestions and even more a code sketch of how you would do this in a better way.
Thanks.

Calling own WCF WebService twice from different BackgroundWorkers closes application

I've written a small WCF WebService (.svc) which I want to call from other applications. It's working fine so far.
In another application I've got a Windows Form. When this is shown, it will call BackgroundWorker1 to get a list of objects from the WebService and show it to the user on it's completed1-method. So far, so good.
Now, after the user selects one object and clicks "ok", then BackgroundWorker2 will call the WebService again to gather more information. But here, within the doWork2-method exactly after the WebService-call, the whole application breaks without any exceptions or errors. It just closes directly after the WebService is called.
This is very weird, because as I have a look at the WebServices log files, it seems to work normal and still logs the successful operation AFTER the other application is closed. So the WebService cannot be the problem, I think.
Another weird thing: If I call the WebService the second time on the GUI thread (and not with BackgroundWorker2), it just works. It blocks the UI, but it works.
So, why is my application just "broken" after the second call without any notification?
Any ideas are very much welcomed.
Thanks in advance.
Greets
Here's some simplified code. The application closes in "bgwGetSingleCar_DoWork":
public partial class MyForm : Form
{
private Controller _ctrl { get; set; }
private Config _config { get; set; }
private List<Cars> _cars { get; set; }
public bool Result { get; private set; }
public MyForm(Controller ctrl, Config config)
{
this._ctrl = ctrl;
this._config = config;
this.Result = false;
InitializeComponent();
}
private void MyForm_Load(object sender, EventArgs e)
{
try
{
this.bgwGetAllOffers.RunWorkerAsync(new WorkerInfo()
{
WorkerType = WorkerType.Type1,
IdLocal = this._config.IdLocal,
IdExternal = this._config.IdExternal,
});
}
catch (Exception ex)
{
// ...
}
}
private void FillList(List<Cars> list)
{
// ...
}
private void btnOk_Click(object sender, EventArgs e)
{
CarListItem v = (CarListItem)this.lstBoxCars.SelectedValue;
this._config.IdExternal = v.IdExternal;
try
{
this.bgwGetSingleCar.RunWorkerAsync(new WorkerInfo()
{
WorkerType = WorkerType.Type2,
IdLocal = this._config.IdLocal,
IdExternal = this._config.IdExternal,
});
}
catch (Exception ex)
{
// ...
}
}
private void bgwGetAllCars_DoWork(object sender, DoWorkEventArgs e)
{
try
{
WorkerInfo info = (WorkerInfo)e.Argument;
Client client = new Client();
GetCarsResult result = client.GetAllCars(new GetAllCarsRequest()
{
IdLocal = info.IdLocal,
IdExternal = info.IdExternal
});
if (!result.Success)
{
// ...
}
if (result.Cars != null)
{
this._cars = result.Cars.ToList();
}
}
catch (Exception ex)
{
/// ...
}
}
private void bgwGetAllCars_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
this.FillList(this._cars);
}
private void bgwGetSingleCar_DoWork(object sender, DoWorkEventArgs e)
{
try
{
WorkerInfo info = (WorkerInfo)e.Argument;
Client client = new Client();
// Application closes after this line, but WebService log still shows activity
GetCarsResult result = client.GetSingleCar(new GetSingleCarRequest()
{
IdLocal = info.IdLocal,
IdExternal = info.IdExternal
});
if (result.Success)
{
this.Result = true;
}
}
catch (Exception ex)
{
/// ...
}
}
private void bgwGetSingleOffer_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
this.DialogResult = System.Windows.Forms.DialogResult.OK;
}
}
public class CarListItem : Car
{
public override string ToString()
{
return ((DateTime)this.LastUpdate).ToString("dd.MM.yyyy - HH:mm");
}
}

I just found my "design break".
It was the button's "DialogResult" which caused the application to close too soon. But strange that the debugger didn't step ahead...

Calling a Class or Method in C# using Mono

I'm having some problems calling a class or method in C# using Mono, can anyone give some help on what I'm doing wrong?
I want this piece of code:
public static void Execute(ScriptHost host)
{
try
{
TesteGUI teste = new TesteGUI(); //?
TesteGUI(); // ?
}
catch(Exception e)
{
}
finally
{
}
}
To call this piece of code:
public TesteGUI(Gtk.Window parentWindow) : base(Gtk.WindowType.Toplevel)
{
base.Modal = false;
base.TransientFor = parentWindow;
base.Decorated = false;
base.WindowPosition = WindowPosition.CenterAlways;
this.MyBuild();
base.KeyReleaseEvent += delegate(object o, KeyReleaseEventArgs args)
{
if (args.Event.Key == Gdk.Key.Escape)
{
this.Destroy();
}
};
}
What is my doing wrong and how can I make it work?
Thank you

You should do it like this:
public static void Execute(ScriptHost host)
{
try
{
TesteGUI teste = new TesteGUI(parentWindow); //where parentWindow is defined somewhere earlier and is of type Gtk.Window
}
catch(Exception e)
{
}
finally
{
}
}