Develop Reference

WinForms REST API Server With Grapevine

I would like to add a REST API server to my WinForms application. I have chosen to use Grapveine for that purpose.
Here's my code:
namespace RestServerTest
{
public partial class Form1 : Form
{
private RestServer mServer;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
mServer = new RestServer();
mServer.Start();
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
mServer.Stop();
mServer.Dispose();
}
}
[RestResource]
class MyRoute
{
[RestRoute]
public IHttpContext HelloWorld(IHttpContext context)
{
// Todo: how access form object from here?
context.Response.SendResponse("Hello, world.");
return context;
}
}
}
Currently I have no idea how to actually access my Form object from the REST route (without using an ugly global/static variable).
How would one do that elegantly?

If you want the current form (or any other object/variable in your project) to be accessible to your routes, you can take advantage of Dynamic Properties. Both the IRestServer and IHttpContext implement IDynamicProperties, which gives you two ways to accomplish your goal.
Add either of these to your Form1_Load() method.
Add a Reference On The Server
server.Properties.Add("CurrentForm", this);
Add a BeforeRouting Event Handler
server.Router.BeforeRouting += cxt =>
{
cxt.Properties.Add("CurrentForm", this);
};
Access a Property In a Route
In either case, you can access the property using the built in extensions methods:
// On the server
var form = context.Server.GetPropertyValueAs<Form1>("CurrentForm");
// On the context
var form = context.GetPropertyValueAs<Form1>("CurrentForm");

Update label through another class

I'm trying to call method Run in script1. Then from script1 call method alert or wait and try to update statusLabel in Form1. But this code has an error.
static Label status = this.Controls.Find("statusLabel", true).FirstOrDefault() as Label;
This code will only work in Form1. Because this return error in another classes. Maybe it is not correct and you know better solution.
P.S. I know how to solve this problem (see below "Not the best solution"), but the code will be ~ 10-30 new lines.
Project
Form1.cs
public partial class Form1 : Form
{
private void statusLabel_Click(object sender, EventArgs e)
{
}
private void Form1_Load(object sender, EventArgs e)
{
script1.Run();
...
script30.Run();
}
}
function.cs (Frequently used functions)
public class function
{
static Label statusLabel = this.Controls.Find("statusLabel", true).FirstOrDefault() as Label;
static public void alert(string str)
{
statusLabel.Text = str;
}
static public void wait(int sec)
{
int i = 0;
while (i++ < sec)
{
statusLabel.Text = "Wait: " + (sec+1-i).ToString();
Thread.Sleep(1000);
}
}
}
script1.cs (script1,script2 ... it is about 30 mini programs)
public class script1
{
static public void Run()
{
function.alert("Script1 is running");
function.wait(5);
function.alert("Script1 is done");
}
}
Not the best solution
remove in function.cs
static Label status = this.Controls.Find("statusLabel", true).FirstOrDefault() as Label;
Form1.cs
public partial class Form1 : Form
{
private void Form1_Load(object sender, EventArgs e)
{
script1.Run(this.statusLabel);
}
}
function.cs
public class function
{
private Label _statusLabel;
public scriptClass(Label statusLabel)
{
_statusLabel = statusLabel;
}
}
script1.cs (script1,script2 ... it is about 30 mini programs)
public class script1
{
static public void Run(Label statusLabel)
{
function _function = new function(statusLabel);
}
}

The statusLabel object is owned by, and should be encapsulated and hidden by, the Form1 class. To ensure good decoupling of your classes, as well as proper data hiding, only the Form1 class should be directly accessing it. And it should (by default) be able to access it via a field named statusLabel (i.e. no need to call this.Controls.Find() (nor should that even work from the function class, since that class also is not the owner of the object, nor of a Controls property).
The correct way to do this is for the script1 class to expose a StatusText property, and an event that is raised when the property value changes. There are two canonical ways to implement the event:
Implement an event named StatusTextChanged
Implement the INotifyPropertyChanged interface
Note that in your example, #2 is not an option because you are using static classes to implement your scripts. IMHO this is inadvisable for a variety of reasons, but since #1 is a perfectly fine solution I won't belabor that point. :)
The first looks like this:
class script1
{
public static string StatusText { get; private set; }
public static event EventHandler StatusTextChanged;
static public void Run()
{
ChangeStatusText("Script1 is running");
function.wait(5);
ChangeStatusText("Script1 is done");
}
static void ChangeStatusText(string text)
{
StatusText = text;
EventHandler handler = StatusTextChanged;
if (handler != null)
{
handler(null, EventArgs.Empty);
}
}
}
Then in Form1:
public partial class Form1
{
private void Form1_Load(object sender, EventArgs e)
{
script1.StatusTextChanged += (sender1, e1) => statusLabel.Text = script1.Text;
script1.Run();
...
script30.StatusTextChanged += (sender1, e1) => statusLabel.Text = script30.Text;
script30.Run();
}
}
Note in the above, each scriptX class has to reimplement the event. You could instead make a base class that each of the scriptX classes inherits, and which contains the event in question. Then the Form1 class need only subscribe to the one base class event. It would also address, or at least minimize the hassle of, the issue of leaving event handlers subscribed to 30 different events.
Of course, in this case then the Form1 class won't know which script is updating the text, but maybe that doesn't matter in your case.
Also note that if you did make the scriptX classes non-static, you might then again run into the issue of having to subscribe multiple times. But that is much more easily handled, since it seems certain in that case you'd use a base class, and so it would be easy to generalize the "subscribe, run script, unsubscribe" logic into a helper method.

MessageBox Display Once

I was wondering if there was a way to display a messagebox in WP8 just once i.e. on app opening.
I have the following code already, very basic.
protected override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
MessageBox.Show("Hi");
}
However, this shows every time the app is opened. I only want it to show the first time.
Is that possible?

I have used this successfully in WP 8.0 Silverlight apps. Create a reusable class, OneTimeDialog:
using System.Windows;
using System.IO.IsolatedStorage;
namespace MyApp
{
public static class OneTimeDialog
{
private static readonly IsolatedStorageSettings _settings = IsolatedStorageSettings.ApplicationSettings;
public static void Show(string uniqueKey, string title, string message)
{
if (_settings.Contains(uniqueKey)) return;
MessageBox.Show(message, title, MessageBoxButton.OK);
_settings.Add(uniqueKey, true);
_settings.Save();
}
}
}
Then use it anywhere in your app, like this:
OneTimeDialog.Show("WelcomeDialog", "Welcome", "Welcome to my app! You'll only see this once.")
Showing a "Hint" or "Welcome" dialog just once is helpful in lots of different types of apps, so I actually have the code above in a Portable Class Library so I can reference it from multiple projects.

Since you need to persist a state across sessions, an isolated storage key-value pair is a good choice. Just check before, and then update:
protected override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
var settings = IsolatedStorageSettings.ApplicationSettings;
if (settings.ContainsKey("messageShown") && (bool)settings["messageShown"] == true)
{
MessageBox.Show("Hi");
settings["messageShown"] = true;
}
}

passing value from another class to textbox in form?

I have a class and a form. the class is intended to do some processes when event is raised and return back the values to the form to display only. I kind of have problem passing values back to form. For instance, I have this code in class print:
public class PrintClass : Form1
{
public void printEventHandler(object sender, EventArgs e)
{
string text = "Process Completed";
append_Tbox(text);
}
}
and the method in form1 to display the text:
public void append_Tbox(string s)
{
TboxPrint.AppendText(s);
}
However, nothing is displayed. I believe there is something wrong, but I can't figure it out.
What is the fastest way to pass values from the class to form?

First off, your processing class shouldn't extend Form1. This is giving you the illusion that you can access the methods of your existing form, but it's not doing what you think it is. You're creating an entirely new form when you do this, and just not showing it. That form has it's own set of all instance fields, so you're not accessing the controls of your main form. Even if this would work (and it won't) it's not a well designed solution.
The proper way to do this is actually much easier. You just need to have your other class return a value from it's method:
public class PrintClass
{
public string DoWork()
{
Thread.Sleep(2000);//placeholder for real work.
return "Process Completed";
}
}
Now your main form can just call that method and append the return value to a textbox.
Once you do this you'll have an entirely separate issue. If you do the work in the UI thread you'll be blocking that UI thread while the work takes place, preventing the form from being repainted, or any other events from being handled. You need to do the work in a background thread and then marshal back to the UI thread to update the UI with the results. There are a number of ways of doing this, but if you have C# 5.0 using await is by far the easiest:
public class Form1 : Form
{
private void SomeEventHandler(object sender, EventArgs args)
{
string result = await Task.Run(()=>new PrintClass().DoWork());
TboxPrint.AppendText(result);
}
}
If you need a C# 4.0 solution you can use ContinueWith, which is more or less what the above will be translated to, but it's not quite as clean of syntax.
public class Form1 : Form
{
private void SomeEventHandler(object sender, EventArgs args)
{
Task.Factory.StartNew(()=>new PrintClass().DoWork())
.ContinueWith(t => TboxPrint.AppendText(t.Result)
, CancellationToken.None
, TaskContinuationOptions.None
, TaskScheduler.FromCurrentSynchronizationContext());
}
}

I have create delegate in Main Form
public delegate void LoginDelegate(string s);
public partial class AirLineReservationMDI : Form
{
LoginDelegate loginAirLineDelegate;
}
loginAirLineDelegate = new LoginDelegate(DisableToolStripMenuItems);
public void DisableToolStripMenuItems(string s)
{
this.viewToolStripMenuItem.Visible = true;
this.bookingToolStripMenuItem.Visible = true;
this.existingUserToolStripMenuItem.Visible = false;
this.newUserToolStripMenuItem.Visible = false;
this.toolStripStatusUserID.Text = "USerID :- "+s;
this.LoginUserId = s;
}
in Another Class, (I have passed delagete object to this class )
I fired the Delegate
logDelegate(textBoxUserName.Text);

I used Action<T> delegate to solve the problem. here is the code and it works fine.
class PrintClass
{
public Action<string> DisplayDelegate;
public void printEventHandler(object sender, EventArgs e)
{
string text = "Event Handled, and text value is passed";
var copy = DisplayDelegate;
if (copy != null)
{
copy(text);
}
}
}
and in `Form1.cs' :
private void Form1_Load(object sender, EventArgs e)
{
PrintClass p = new PrintClass();
BtnPrint.Click += p.printEventHandler;
//subscrite the displayevent method to action delegate
p.DisplayDelegate += DisplayEvent;
}
public void DisplayEvent(string s)
{
Invoke(new Action(() => TboxPrint.AppendText(s)));
}
so the text 'Event Handled, and text value is passed' is displayed on the textbox.
I m not sure if it is the efficient way.
Thanks guys.

ASP.NET call button action from different class

I have a class Lot with a function AddPiece(piece).
I also have a Page with a button btnPanel that on click fires the function
public void btnPanel_OnClick(object sender, EventArgs e){}
I want to call the btnPanel_OnClick from the Addpiece function but when I try to do it it does not show in the intlliSense and I get this compilation error "The name 'btnPanel_OnClick' does not exist in the current context". Both classes are in the same namespace. Is this possible?
Here is what I have:
namespace GraphicW_Array
{
public partial class Board : System.Web.UI.Page
{
public void btnPanel_OnClick(object sender, EventArgs e)
{
...code...
}
}
}
and
namespace GraphicW_Array
{
public class Lot
{
public void addPiece(int piece)
{
lotPresent[lotLoad] = piece;
lotLoad++;
}
}
}

I think the answer is yes you can but you probably don't want to. To call the method you need and instance of your page class so you could do
namespace GraphicW_Array
{
public class Lot
{
public void addPiece(int piece)
{
lotPresent[lotLoad] = piece;
lotLoad++;
var myPage = new Board();
myPage.btnPanel_OnClick(null,EventArgs.Empty);
}
}
}
But what would that actually do? I have no idea because you haven't posted the code but i suspect it won't do anything useful for you.
What are you actually trying to achieve?
Maybe this is want you want
namespace GraphicW_Array
{
public class Lot
{
public void addPiece(int piece, Board myPAge)
{
lotPresent[lotLoad] = piece;
lotLoad++;
myPage.btnPanel_OnClick(null,EventArgs.Empty);
}
}
}
Then in your page you can call it like this:
var myLot = new Lot();
myLot.addPiece(4,this);

Yes, this is possible.
Ensure your Lot class has a reference to the Board class in order to be able to call it, or define an event on it that the Board class can subscribe to and that will call this mathod when the event fires.
If you don't use the sender and e parameters, just pass a null and EventArgs.Empty.

You can call page's event by passing either null(if sender and EventArgs is not mandatory) but below is the better way to go.
It is not wise and not good practice to call a event from a class, however you can create another method with arguments in your class and then call it with desired parameters when it is needed.
This is can be accomplished as below:
Say you have below event
public void btnPanel_OnClick(object sender, EventArgs e)
{
//Do some common tasks to do here
}
Rearrange it as below:
public void btnPanel_OnClick(object sender, EventArgs e)
{
Lot lot = new Lot();
lot.CommonFunction(arg1, arg2); // Pass required data
}
public class Lot
{
public void AFunction()
{
//Do something
//...
CommonFunction(arg1, arg2); // Pass required data
//...
//Do something
}
public void CommonFunction(string arg1, string arg2)
{
// Do some common tasks to do here
}
}