WPF TextBox Search - c#

I have a quickFind TextBox. I want to filter a collection for records that contain the quickFind string.
How can I delay the search until the user has stopped typing for 2 seconds?

Here's the ReactiveUI way to do the whole thing (filtering the items after a 2sec delay):
// These are defined in your ViewModel class as settable Properties
string FilterText;
ReactiveList<Record> ListOfRecords;
IReactiveDerivedList<Record> FilteredRecords;
// This is in your ViewModel constructor
FilteredRecords = ListOfRecords.CreateDerivedCollection(
x => !String.IsNullOrWhiteSpace(FilterText) ? recordContainsString(FilterText) : true,
x => x.Id,
this.WhenAnyValue(x => x.FilterText).Throttle(TimeSpan.FromSeconds(2.0));
If all you want to do is find out when a property has changed but after an idle time, it's:
this.WhenAnyValue(x => x.SomeProperty)
.Throttle(TimeSpan.FromSeconds(2.0), RxApp.MainThreadScheduler)
.Subscribe(x => Console.WriteLine("The item is " + x);
I love the Timer and Lock example because it shows how much easier ReactiveUI is :)

below is a class that I'm hoping does the trick for you. including sample usage shown at the bottom.
public class EventDelayer
{
/// <summary>
/// Contains info on an individual event that was queued;
/// </summary>
public class DelayedEventInfo
{
private readonly object _sender;
private readonly EventArgs _eventArgs;
private readonly DateTime _eventTime;
public DelayedEventInfo(object sender, EventArgs eventArgs, DateTime eventTime)
{
_sender = sender;
_eventArgs = eventArgs;
_eventTime = eventTime;
}
public object Sender { get { return _sender; } }
public EventArgs EventArgs { get { return _eventArgs; } }
public DateTime EventTime { get { return _eventTime; } }
}
/// <summary>
/// contains a list of
/// </summary>
public class DelayedEventArgs : EventArgs, IEnumerable<DelayedEventInfo>
{
private readonly List<DelayedEventInfo> _eventInfos;
public DelayedEventArgs(IEnumerable<DelayedEventInfo> eventInfos)
{
_eventInfos = new List<DelayedEventInfo>(eventInfos);
}
public IEnumerator<DelayedEventInfo> GetEnumerator()
{
return _eventInfos.GetEnumerator();
}
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
return _eventInfos.GetEnumerator();
}
}
private readonly List<DelayedEventInfo> _infoList = new List<DelayedEventInfo>();
private readonly TimeSpan _delayTime;
private readonly object _lock = new object();
private System.Threading.Timer _timer;
public event EventHandler<DelayedEventArgs> DelayedEvent;
public EventDelayer(TimeSpan delayTime)
{
_delayTime = delayTime;
}
/// <summary>
/// call to 'enqueue' an event.
/// </summary>
public void Enqueue(object sender, EventArgs args)
{
lock (_lock)
{
_infoList.Add(new DelayedEventInfo(sender, args, DateTime.Now));
if (_timer != null)
{
_timer.Dispose();
_timer = null;
}
_timer = new System.Threading.Timer(ThreadProc, this, _delayTime, TimeSpan.FromMilliseconds(-1));
}
}
/// <summary>
/// raises the event.
/// </summary>
private void HandleTimer()
{
lock (_lock)
{
var ev = this.DelayedEvent;
if (ev != null)
{
DelayedEventArgs args = new DelayedEventArgs(_infoList);
Invoke(()=> ev(this, args));
}
_infoList.Clear();
}
}
private static void ThreadProc(Object stateInfo)
{
EventDelayer thisObj = (EventDelayer)stateInfo;
thisObj.HandleTimer();
}
private static Lazy<System.Windows.Threading.Dispatcher> _dispatchObject = new Lazy<System.Windows.Threading.Dispatcher>(() =>
{
if (Application.Current != null)
{
return Application.Current.Dispatcher;
}
else
{
return null;
}
});
public static void Invoke(Action action)
{
if (_dispatchObject.Value == null || _dispatchObject.Value.CheckAccess())
{
action();
}
else
{
_dispatchObject.Value.Invoke(action);
}
}
}
private class ExampleUsage
{
/// <summary>
/// shows how to create a event delayer and use it to listen to the events from a text box and call if no further changes for 2 seconds.
/// </summary>
private static void ShowUsage(System.Windows.Controls.TextBox textBox)
{
EventDelayer eventDelayer = new EventDelayer(TimeSpan.FromSeconds(2));
textBox.TextChanged += eventDelayer.Enqueue;
eventDelayer.DelayedEvent += eventDelayer_DelayedEvent;
}
/// <summary>
/// redo search here. if required you can access the event args originally raised from the textbox through the event args of this method
/// </summary>
static void eventDelayer_DelayedEvent(object sender, EventDelayer.DelayedEventArgs e)
{
foreach (var eventInfo in e)
{
var originalSender = eventInfo.Sender;
var args = eventInfo.EventArgs;
var timeInitiallyCalled = eventInfo.EventTime;
}
}
}

Bind the textbox text to a string, then set a delay in the binding
<TextBox>
<TextBox.Text>
<Binding Path="searchText" UpdateSourceTrigger="PropertyChanged" Delay="2000" />
</TextBox.Text>
</TextBox>

Related

object reference is required, also dump object into messagebox tips

i'm getting an error with this code new RoutedEventHandler(Notifications.showNotifications(window)); saying:
An object reference is required for the non-static field, method, or
property 'Notifications.showNotifications(Window)'
Also, can I get an example of how I could dump out each Dictionary object from within my _notifications object in the runtimeObject class? I need to do this when showNotifications is called!
When I say dump out, based on the test notifications which I try to add in the code, I just want to display a MessageBox to show that they are being added, so using the code above the MessageBox would show:
MessageBox
Error Code: 1, Text: Error 1
Error Code: 2, Text: Normal Message
Error Code: 3, Text: Tip
App.xaml.cs
namespace Test_Project
{
/// <summary>
/// Interaction logic for App.xaml
/// </summary>
public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
//Startup
Window main = new MainWindow();
main.Show();
//Attach Event Handlers to MainWindow
if (!attachEventHandlers(main))
{
MessageBox.Show("Fatal Error: Unable to attach event handlers, contact administrator!",
"Fatal Error!",
MessageBoxButton.OK,
MessageBoxImage.Exclamation);
}
}
public bool attachEventHandlers(Window window)
{
//window.MouseMove += new RoutedEventHandler(Notifications.showNotifications(window));
return true;
}
}
public class Notifications
{
/// <summary>
/// Show the notifications
/// </summary>
/// <param name="window"></param>
public void showNotifications(Window window)
{
// Find the resource, then cast it to a runtimeObject
var runtime = (runtimeObject)Application.Current.TryFindResource("runtimeVariables");
//Create messagebox with all the notifications in to test
}
public bool addNotifications()
{
// Find the resource, then cast it to a runtimeObject
var runtime = (runtimeObject)Application.Current.TryFindResource("runtimeVariables");
//Create Dictionary
Dictionary<int, string> arr = new Dictionary<int, string>();
arr.Add(1, "Error 1");
arr.Add(2, "Normal Message");
arr.Add(3, "Tip");
//Create test notifications
runtime.notifications.Add(arr);
return true;
}
}
/// <summary>
/// Global values for use during application runtime
/// </summary>
public class runtimeObject : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string name)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
}
//Can the application be closed?
private bool _inProgress = false;
public bool inProgress
{
get { return _inProgress; }
set
{
if (_inProgress != value)
{
_inProgress = value;
OnPropertyChanged("inProgress");
}
}
}
/// <summary>
/// Notifications held
/// Array((int)type,(string)"message")
/// </summary>
private List<Dictionary<int, string>> _notifications;
public List<Dictionary<int, string>> notifications
{
get { return _notifications; }
set
{
if (_notifications != value)
{
_notifications = value;
OnPropertyChanged("notifications");
}
}
}
//Selected folder to search in
private int _uploadProgress = 0;
public int uploadProgress
{
get { return _uploadProgress; }
set
{
if (_uploadProgress != value)
{
//int Angle = (_uploadProgress * 360) / 100;
//Classes.CircularProgress.RenderArc(Angle);
_uploadProgress = value;
OnPropertyChanged("uploadProgress");
}
}
}
}
}

Cancel an async task

For example I have something like this. When I am clicking on first button it start's async process and then I am clicking second button it start's second process. But I need only one process to work after clicking on each button. How can I cancel other process?
namespace WpfApplication55
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
TestCombo TC = new TestCombo();
public MainWindow()
{
DataContext = TC;
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
TC.Begin(60);
}
private void Button_Click1(object sender, RoutedEventArgs e)
{
TC.Begin(120);
}
}
public class TestCombo:INotifyPropertyChanged
{
private int someData;
public int SomeData
{
get { return someData; }
set { someData = value; RaisePropertyChanged("SomeData"); }
}
public void StartCount(int input)
{
SomeData = input;
while (input>0)
{
System.Threading.Thread.Sleep(1000);
input -= 1;
SomeData = input;
}
}
public void Begin(int input)
{
Action<int> Start = new Action<int>(StartCount);
IAsyncResult result = Start.BeginInvoke(input, null, null);
}
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged (string info)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
}
I'm not exactly sure how you want the while condition in StartCount to work but as long as you evaluating the new CancellationToken you should be good to cancel. Remember the Thread.Sleep won't cancel while its sleeping. So you may have up to a 1s delay.
public void StartCount(int input, CancellationToken token)
{
SomeData = input;
while (input > 0 && !token.IsCancellationRequested)
{
System.Threading.Thread.Sleep(1000);
input -= 1;
SomeData = input;
}
}
IAsyncResult process;
public void Begin(int input)
{
if (process != null && !process.IsCompleted)
((CancellationTokenSource)process.AsyncState).Cancel();
Action<int, CancellationToken> Start = new Action<int, CancellationToken>(StartCount);
var cancelSource = new CancellationTokenSource();
process = Start.BeginInvoke(input,cancelSource.Token, null, cancelSource);
}
I would use Microsoft's Reactive Framework for this.
Here's your class:
public class TestCombo : INotifyPropertyChanged
{
private int someData;
public int SomeData
{
get { return someData; }
set { someData = value; RaisePropertyChanged("SomeData"); }
}
private SingleAssignmentDisposable _subscription = new SingleAssignmentDisposable();
public void Begin(int input)
{
_subscription.Disposable =
Observable
.Interval(TimeSpan.FromSeconds(1.0))
.Select(x => input - (int)x)
.Take(input)
.ObserveOnDispatcher()
.Subscribe(x => this.SomeData = x);
}
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged (string info)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
The two key parts to this solution is first the observable query subscription which does all of the timing, computes the value to assign to SomeData and marshals the assignment to the UI thread.
The second is the SingleAssignmentDisposable. When you assign a new IDisposable to its Disposable property it will dispose any previously assigned IDisposable.
The disposing cancels the previous subscription.
Just NuGet "Rx-WPF" to get the WPF bits for Rx.
Try something like this:
namespace WpfApplication55
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
TestCombo TC = new TestCombo();
CancellationTokenSource cts;
public MainWindow()
{
DataContext = TC;
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
if (cts != null)
{
cts.Cancel();
}
cts = new CancellationTokenSource();
await TC.DoAsync(60, cts.Token);
}
private void Button_Click1(object sender, RoutedEventArgs e)
{
if (cts != null)
{
cts.Cancel();
}
cts = new CancellationTokenSource();
await TC.DoAsync(120, cts.Token);
}
}
public class TestCombo:INotifyPropertyChanged
{
private int someData;
public int SomeData
{
get { return someData; }
set { someData = value; RaisePropertyChanged("SomeData"); }
}
public void StartCount(int input)
{
SomeData = input;
while (input>0)
{
System.Threading.Thread.Sleep(1000);
input -= 1;
SomeData = input;
}
}
public Task DoAsync(int input, CancellationToken cancellationToken)
{
return Task.Run(StartCount, cancellationToken);
}
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged (string info)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
}
Try using class CancellationTokenSource;
See code below-
CancellationTokenSource ctstask = new CancellationTokenSource();
ctstask.Cancel();//This line should be called from 2nd button click.

Test helper for expected events sequence reporting duplicate events

I have a helper method for my unit tests that asserts that a specific sequence of events were raised in a specific order. The code is as follows:
public static void ExpectEventSequence(Queue<Action<EventHandler>> subscribeActions, Action triggerAction)
{
var expectedSequence = new Queue<int>();
for (int i = 0; i < subscribeActions.Count; i++)
{
expectedSequence.Enqueue(i);
}
ExpectEventSequence(subscribeActions, triggerAction, expectedSequence);
}
public static void ExpectEventSequence(Queue<Action<EventHandler>> subscribeActions, Action triggerAction, Queue<int> expectedSequence)
{
var fired = new Queue<int>();
var actionsCount = subscribeActions.Count;
for(var i =0; i< actionsCount;i++)
{
subscription((o, e) =>
{
fired.Enqueue(i);
});
}
triggerAction();
var executionIndex = 0;
var inOrder = true;
foreach (var firedIndex in fired)
{
if (firedIndex != expectedSequence.Dequeue())
{
inOrder = false;
break;
}
executionIndex++;
}
if (subscribeActions.Count != fired.Count)
{
Assert.Fail("Not all events were fired.");
}
if (!inOrder)
{
Assert.Fail(string.Format(
CultureInfo.CurrentCulture,
"Events were not fired in the expected sequence from element {0}",
executionIndex));
}
}
Example usage is as follows:
[Test()]
public void FillFuel_Test([Values(1, 5, 10, 100)]float maxFuel)
{
var fuelTank = new FuelTank()
{
MaxFuel = maxFuel
};
var eventHandlerSequence = new Queue<Action<EventHandler>>();
eventHandlerSequence.Enqueue(x => fuelTank.FuelFull += x);
//Dealing with a subclass of EventHandler
eventHandlerSequence.Enqueue(x => fuelTank.FuelChanged += (o, e) => x(o, e));
Test.ExpectEventSequence(eventHandlerSequence, () => fuelTank.FillFuel());
}
And the code under test:
public float Fuel
{
get
{
return fuel;
}
private set
{
var adjustedFuel = Math.Max(0, Math.Min(value, MaxFuel));
if (fuel != adjustedFuel)
{
var oldFuel = fuel;
fuel = adjustedFuel;
RaiseCheckFuelChangedEvents(oldFuel);
}
}
}
public void FillFuel()
{
Fuel = MaxFuel;
}
private void RaiseCheckFuelChangedEvents(float oldFuel)
{
FuelChanged.FireEvent(this, new FuelEventArgs(oldFuel, Fuel));
if (fuel == 0)
{
FuelEmpty.FireEvent(this, EventArgs.Empty);
}
else if (fuel == MaxFuel)
{
FuelFull.FireEvent(this, EventArgs.Empty);
}
if (oldFuel == 0 && Fuel != 0)
{
FuelNoLongerEmpty.FireEvent(this, EventArgs.Empty);
}
else if (oldFuel == MaxFuel && Fuel != MaxFuel)
{
FuelNoLongerFull.FireEvent(this, EventArgs.Empty);
}
}
So the test expects FuelFilled to be fired before FuelChanged but in actuality FuelChanged is fired first, which fails the test.
However my test is instead reporting that FuelChanged is being fired twice, but when I step through the code it is clear that FuelFilled is fired after FuelChanged and FuelChanged is only fired once.
I assumed that it was something to do with the way lambdas work with local state, maybe the for loop iterator variable was only ever set to the final value, so I replaced the for loop with this:
var subscriptions = subscribeActions.ToList();
foreach (var subscription in subscriptions)
{
subscription((o, e) =>
{
var index = subscriptions.IndexOf(subscription);
fired.Enqueue(index);
});
}
However the result is the same, fired contains {1;1} instead of {1;0}.
Now I'm wondering if the same lambda is being assigned to both events instead of using the different subscription / index state. Any ideas?
Update: I was unable to get success with either answer posted so far (same as my initial results), despite their similarities to my actual code, so I presume the issue is located elsewhere in my FuelTank code. I've pasted the full code for FuelTank below:
public class FuelTank
{
public FuelTank()
{
}
public FuelTank(float initialFuel, float maxFuel)
{
MaxFuel = maxFuel;
Fuel = initialFuel;
}
public float Fuel
{
get
{
return fuel;
}
private set
{
var adjustedFuel = Math.Max(0, Math.Min(value, MaxFuel));
if (fuel != adjustedFuel)
{
var oldFuel = fuel;
fuel = adjustedFuel;
RaiseCheckFuelChangedEvents(oldFuel);
}
}
}
private float maxFuel;
public float MaxFuel
{
get
{
return maxFuel;
}
set
{
if (value < 0)
{
throw new ArgumentOutOfRangeException("MaxFuel", value, "Argument must be not be less than 0.");
}
maxFuel = value;
}
}
private float fuel;
public event EventHandler<FuelEventArgs> FuelChanged;
public event EventHandler FuelEmpty;
public event EventHandler FuelFull;
public event EventHandler FuelNoLongerEmpty;
public event EventHandler FuelNoLongerFull;
public void AddFuel(float fuel)
{
Fuel += fuel;
}
public void ClearFuel()
{
Fuel = 0;
}
public void DrainFuel(float fuel)
{
Fuel -= fuel;
}
public void FillFuel()
{
Fuel = MaxFuel;
}
private void RaiseCheckFuelChangedEvents(float oldFuel)
{
FuelChanged.FireEvent(this, new FuelEventArgs(oldFuel, Fuel));
if (fuel == 0)
{
FuelEmpty.FireEvent(this, EventArgs.Empty);
}
else if (fuel == MaxFuel)
{
FuelFull.FireEvent(this, EventArgs.Empty);
}
if (oldFuel == 0 && Fuel != 0)
{
FuelNoLongerEmpty.FireEvent(this, EventArgs.Empty);
}
else if (oldFuel == MaxFuel && Fuel != MaxFuel)
{
FuelNoLongerFull.FireEvent(this, EventArgs.Empty);
}
}
}
FuelEventArgs looks like this:
public class FuelEventArgs : EventArgs
{
public float NewFuel
{
get;
private set;
}
public float OldFuel
{
get;
private set;
}
public FuelEventArgs(float oldFuel, float newFuel)
{
this.OldFuel = oldFuel;
this.NewFuel = newFuel;
}
}
The FireEvent extension method is looks like this:
public static class EventHandlerExtensions
{
/// <summary>
/// Fires the event. This method is thread safe.
/// </summary>
/// <param name="handler"> The handler. </param>
/// <param name="sender"> Source of the event. </param>
/// <param name="args"> The <see cref="EventArgs"/> instance containing the event data. </param>
public static void FireEvent(this EventHandler handler, object sender, EventArgs args)
{
var handlerCopy = handler;
if (handlerCopy != null)
{
handlerCopy(sender, args);
}
}
/// <summary>
/// Fires the event. This method is thread safe.
/// </summary>
/// <typeparam name="T"> The type of event args this handler has. </typeparam>
/// <param name="handler"> The handler. </param>
/// <param name="sender"> Source of the event. </param>
/// <param name="args"> The <see cref="EventArgs"/> instance containing the event data. </param>
public static void FireEvent<T>(this EventHandler<T> handler, object sender, T args) where T : EventArgs
{
var handlerCopy = handler;
if (handlerCopy != null)
{
handlerCopy(sender, args);
}
}
}
The full test code can be found above in the question, there is no other code called during test execution.
I am using NUnit test framework via the Unity Testing Tools plugin for the Unity3D engine, .NET version 3.5 (ish, it's closer to Mono 2.0, I believe), and Visual Studio 2013.
Update 2:
After extracting the code and tests to their own project (outside of the Unity3D ecosystem) all tests run as expected, so I'm going to have to chalk this one up to a bug in the Unity -> Visual Studio bridge.
I have the following implementation based upon Nick's question.
First the class for the FuelTank:
public class FuelTank
{
private float fuel;
//Basic classes for the event handling, could be done by providing a few simple delegates,
//but this is just to stick as close to the original question as possible.
public FuelChanged FuelChanged = new FuelChanged();
public FuelEmpty FuelEmpty = new FuelEmpty();
public FuelFull FuelFull = new FuelFull();
public FuelNoLongerEmpty FuelNoLongerEmpty = new FuelNoLongerEmpty();
public FuelNoLongerFull FuelNoLongerFull = new FuelNoLongerFull();
public float MaxFuel { get; set; }
public float Fuel
{
get
{
return fuel;
}
private set
{
var adjustedFuel = Math.Max(0, Math.Min(value, MaxFuel));
if (fuel != adjustedFuel)
{
var oldFuel = fuel;
fuel = adjustedFuel;
RaiseCheckFuelChangedEvents(oldFuel);
}
}
}
public void FillFuel()
{
Fuel = MaxFuel;
}
private void RaiseCheckFuelChangedEvents(float oldFuel)
{
FuelChanged.FireEvent(this, new FuelEventArgs(oldFuel, Fuel));
if (fuel == 0)
{
FuelEmpty.FireEvent(this, EventArgs.Empty);
}
else if (fuel == MaxFuel)
{
FuelFull.FireEvent(this, EventArgs.Empty);
}
if (oldFuel == 0 && Fuel != 0)
{
FuelNoLongerEmpty.FireEvent(this, EventArgs.Empty);
}
else if (oldFuel == MaxFuel && Fuel != MaxFuel)
{
FuelNoLongerFull.FireEvent(this, EventArgs.Empty);
}
}
}
As the code for the event handlers was missing, I made an assumption to use this. As the comment describes in the previous code block, it could be done more easily with plain delegates. It's just a matter of choice, for which I think this implementation isn't the best yet, but suitable enough for debugging:
public class FuelEventArgs : EventArgs
{
private float oldFuel, newFuel;
public FuelEventArgs(float oldFuel, float newFuel)
{
this.oldFuel = oldFuel;
this.newFuel = newFuel;
}
}
public class FuelEvents
{
public event EventHandler FireEventHandler;
public virtual void FireEvent(object sender, EventArgs fuelArgs)
{
EventHandler handler = FireEventHandler;
if (null != handler)
handler(this, fuelArgs);
}
}
public class FuelChanged : FuelEvents
{
public override void FireEvent(object sender, EventArgs fuelArgs)
{
Console.WriteLine("Fired FuelChanged");
base.FireEvent(sender, fuelArgs);
}
}
public class FuelEmpty : FuelEvents
{
public override void FireEvent(object sender, EventArgs fuelArgs)
{
Console.WriteLine("Fired FuelEmpty");
base.FireEvent(sender, fuelArgs);
}
}
public class FuelFull : FuelEvents
{
public override void FireEvent(object sender, EventArgs fuelArgs)
{
Console.WriteLine("Fired FuelFull");
base.FireEvent(sender, fuelArgs);
}
}
public class FuelNoLongerEmpty : FuelEvents
{
public override void FireEvent(object sender, EventArgs fuelArgs)
{
Console.WriteLine("Fired FuelNoLongerEmpty");
base.FireEvent(sender, fuelArgs);
}
}
public class FuelNoLongerFull : FuelEvents
{
public override void FireEvent(object sender, EventArgs fuelArgs)
{
Console.WriteLine("Fired FuelNoLongerFull");
base.FireEvent(sender, fuelArgs);
}
}
And to test it all, I used this class, containing most code from the original question:
[TestFixture]
public class Tests
{
public static void ExpectEventSequence(Queue<Action<EventHandler>> subscribeActions, Action triggerAction)
{
var expectedSequence = new Queue<int>();
for (int i = 0; i < subscribeActions.Count; i++)
{
expectedSequence.Enqueue(i);
}
ExpectEventSequence(subscribeActions, triggerAction, expectedSequence);
}
public static void ExpectEventSequence(Queue<Action<EventHandler>> subscribeActions, Action triggerAction, Queue<int> expectedSequence)
{
var fired = new Queue<int>();
var actionsCount = subscribeActions.Count;
//This code has been commented out due to the fact that subscription is unknown here.
//I stuck to use the last solution that Nick provided himself
//for (var i = 0; i < actionsCount; i++)
//{
// subscription((o, e) =>
// {
// fired.Enqueue(i);
// });
//}
var subscriptions = subscribeActions.ToList();
foreach (var subscription in subscriptions)
{
subscription((o, e) =>
{
var index = subscriptions.IndexOf(subscription);
Console.WriteLine("[ExpectEventSequence] Found index: {0}", index);
fired.Enqueue(index);
});
}
triggerAction();
var executionIndex = 0;
var inOrder = true;
foreach (var firedIndex in fired)
{
if (firedIndex != expectedSequence.Dequeue())
{
inOrder = false;
break;
}
executionIndex++;
Console.WriteLine("Execution index: {0}", executionIndex);
}
if (subscribeActions.Count != fired.Count)
{
Assert.Fail("Not all events were fired.");
}
if (!inOrder)
{
Console.WriteLine("Contents of Fired Queue: {0}", PrintValues(fired));
Assert.Fail(string.Format(
CultureInfo.CurrentCulture,
"Events were not fired in the expected sequence from element {0}",
executionIndex));
}
}
private static string PrintValues(Queue<int> myCollection)
{
return string.Format( "{{0}}", string.Join(",", myCollection.ToArray()));
}
[Test()]
[ExpectedException(typeof(DivideByZeroException))]
public void FillFuel_Test([Values(1, 5, 10, 100)]float maxFuel)
{
var fuelTank = new FuelTank()
{
MaxFuel = maxFuel
};
var eventHandlerSequence = new Queue<Action<EventHandler>>();
eventHandlerSequence.Enqueue(x => fuelTank.FuelFull.FireEventHandler += x);
//Dealing with a subclass of EventHandler
eventHandlerSequence.Enqueue(x => fuelTank.FuelChanged.FireEventHandler += (o, e) => x(o, e));
ExpectEventSequence(eventHandlerSequence, () => fuelTank.FillFuel());
}
}
Now, when running the tests with NUnit, I noticed the following results:
The first event that got triggered was the FuelChanged event, this causes the fired queue within the method
public static void ExpectEventSequence(Queue<Action<EventHandler>> subscribeActions, Action triggerAction, Queue<int> expectedSequence)
to contain {1}.
The next event that triggers is the FuelFull event, which means that the fired queue now contains:
{1,0} as expected according to the question of Nick.
The last event that triggers is the FuelNoLongerEmpty event and this one fails the test.
Note:
As this code does not yet provide an answer to the original question of the fact that lambda's might cause some interference, as the code I provided above, does just the right thing.
The following rules apply to variable scope in lambda expressions:
A variable that is captured will not be garbage-collected until the
delegate that references it goes out of scope.
Variables introduced within a lambda expression are not visible in
the outer method.
A lambda expression cannot directly capture a ref or out parameter
from an enclosing method.
A return statement in a lambda expression does not cause the
enclosing method to return.
A lambda expression cannot contain a goto statement, break statement,
or continue statement whose target is outside the body or in the body
of a contained anonymous function.
So the problem in Nick's original question might be caused by the fact that you enumerate over a queue. While enumerating and passing these directly to a lambda expression, you will work with a reference. A trick might be to actually de-reference it by copying it to a local variable within the scope of the iteration loop. This is exactly what smiech is referring to in his post.
EDIT:
I've just looked into it again for you. Are you sure the 'challenge' that you are having is not just the fact that comparing the fired dictionary's indices to the expectedSequence.Dequeue is happening in reversed order? Please note that queue's are FIFO based, so when dequeueing, it will retrieve the first that is inserted...
I noticed that (according to my code) the fired dictionary contains {1,0} whereas the expectedSequence dictionary contains {0,1}. By looking at the expected events, this is good for the expectedSequence queue. So actually the fired queue (filled within your last code block) is built up incorrectly by means of the 'age' of the eventhandler.
When I change one statement within the code that you provided in the original
public static void ExpectEventSequence(Queue<Action<EventHandler>> subscribeActions, Action triggerAction, Queue<int> expectedSequence)
method from
var subscriptions = subscribeActions.ToList();
foreach (var firedIndex in fired)
{
if (firedIndex != expectedSequence.Dequeue())
{
inOrder = false;
break;
}
executionIndex++;
Console.WriteLine("Execution index: {0}", executionIndex);
}
to this:
//When comparing indexes, you'll probably need to reverse the fired queue
fired = new Queue<int>(fired.Reverse());
foreach (var firedIndex in fired)
{
if (firedIndex != expectedSequence.Dequeue())
{
inOrder = false;
break;
}
executionIndex++;
Console.WriteLine("Execution index: {0}", executionIndex);
}
then everything in your test will pass flawlessly, as you can see with this screenshot:
for the first part: yes, it had to do with the way lambdas variable scope. See Access to Modified Closure.
Because I spent some time trying to figure it out, I allow myself to paste the code I've used (all tests passing).
class Test
{
public static void ExpectEventSequence(Queue<Action<EventHandler>> subscribeActions, Action triggerAction)
{
var expectedSequence = new Queue<int>();
for (int i = 0; i < subscribeActions.Count; i++)
expectedSequence.Enqueue(i);
ExpectEventSequence(subscribeActions, triggerAction, expectedSequence);
}
public static void ExpectEventSequence(Queue<Action<EventHandler>> subscribeActions, Action triggerAction, Queue<int> expectedSequence)
{
var fired = new Queue<int>();
var subscriptions = subscribeActions.ToList();
foreach (var subscription in subscriptions)
{
subscription((o, e) =>
{
var index = subscriptions.IndexOf(subscription);
fired.Enqueue(index);
});
}
triggerAction();
var executionIndex = 0;
var inOrder = true;
foreach (var firedIndex in fired)
{
if (firedIndex != expectedSequence.Dequeue())
{
inOrder = false;
break;
}
executionIndex++;
}
if (subscribeActions.Count != fired.Count)
Assert.Fail("Not all events were fired.");
if (!inOrder)
Assert
.Fail(string.Format(
CultureInfo.CurrentCulture,
"Events were not fired in the expected sequence from element {0}",
executionIndex));
}
}
public class Fueled
{
public event EventHandler<FuelEventArgs> FuelChanged = delegate { };
public event EventHandler FuelEmpty = delegate { };
public event EventHandler FuelFull = delegate { };
public event EventHandler FuelNoLongerFull = delegate { };
public event EventHandler FuelNoLongerEmpty = delegate { };
private float fuel;
public float Fuel
{
get{ return fuel; }
private set
{
var adjustedFuel = Math.Max(0, Math.Min(value, MaxFuel));
if (fuel != adjustedFuel)
{
var oldFuel = fuel;
fuel = adjustedFuel;
RaiseCheckFuelChangedEvents(oldFuel);
}
}
}
public void FillFuel()
{
Fuel = MaxFuel;
}
public float MaxFuel { get; set; }
private void RaiseCheckFuelChangedEvents(float oldFuel)
{
FuelChanged(this, new FuelEventArgs(oldFuel, Fuel));
if (fuel == 0)
FuelEmpty(this, EventArgs.Empty);
else if (fuel == MaxFuel)
FuelFull(this, EventArgs.Empty);
if (oldFuel == 0 && Fuel != 0)
FuelNoLongerEmpty(this, EventArgs.Empty);
else if (oldFuel == MaxFuel && Fuel != MaxFuel)
FuelNoLongerFull(this, EventArgs.Empty);
}
}
public class FuelEventArgs : EventArgs
{
public FuelEventArgs(float oldFuel, float fuel)
{
}
}
[TestFixture]
public class Tests
{
[Test()]
public void FillFuel_Test([Values(1, 5, 10, 100)]float maxFuel)
{
var fuelTank = new Fueled()
{
MaxFuel = maxFuel
};
var eventHandlerSequence = new Queue<Action<EventHandler>>();
//Dealing with a subclass of EventHandler
eventHandlerSequence.Enqueue(x => fuelTank.FuelChanged += (o, e) => x(o, e));
eventHandlerSequence.Enqueue(x => fuelTank.FuelFull += x);
Test.ExpectEventSequence(eventHandlerSequence, () => fuelTank.FillFuel());
}
}
Basically I've only changed the order of expected events in test method. If you are still getting incorrect results after changing the loop I think the problem must be outside of your pasted code scope. I'm using VS 2013 community + resharper 8 , nunit 2.6.4.14350
Edit: different approach
I was trying to solve the problem you actually posted, but maybe this will actually be what you want:
wouldn't you consider trying a simplified version of your approach?:
[Test()]
public void FillFuel_Test([Values(1, 5, 10, 100)]float maxFuel)
{
var fuelTank = new Fueled()
{
MaxFuel = maxFuel
};
var expectedEventSequence = new[]
{
"FuelChanged",
"FuelFull"
};
var triggeredEventSequence = new List<string>();
fuelTank.FuelChanged += (o, e) => triggeredEventSequence.Add("FuelChanged");
fuelTank.FuelFull += (o, e) => triggeredEventSequence.Add("FuelFull");
fuelTank.FillFuel();
Assert.AreEqual(expectedEventSequence,triggeredEventSequence);
}

MVVM Detect property change of subclass

I am using SimpleMVVM and have two separate classes (models), one using the second like this:
public class Database : ModelBase<Database>
{
public String ServerName //{ get; set; }
{
get { return _ServerName; }
set
{
if (_ServerName != value)
{
_ServerName = value;
NotifyPropertyChanged(m => m.ServerName);
}
}
}
private String _ServerName = "MyTestServer";
// other properties removed for brevity
}
public class MyConfiguration
{
/// <summary>
/// Database information
/// </summary>
public Database DatabaseInfo
{
get { return _DatabaseInfo; }
set
{
if (_DatabaseInfo != value)
{
_DatabaseInfo = value;
NotifyPropertyChanged(m => m.DatabaseInfo);
}
}
}
private Database _DatabaseInfo = new Database();
}
When 'ServerName' is changed, the NotifyPropertyChanged(m => m.ServerName); command executes but NOT NotifyPropertyChanged(m => m.DatabaseInfo);
How do I make the NotifyPropertyChanged(m => m.DatabaseInfo); fire whenever one of the properties of Database changes?
You can use the PropertyChanged event of the INotifyPropertyChanged interface to tell you when the child property changes.
In your MyConfiguration class:
public Database DatabaseInfo
{
get { return _DatabaseInfo; }
set
{
if (_DatabaseInfo != value)
{
_DatabaseInfo = value;
NotifyPropertyChanged(m => m.DatabaseInfo);
DatabaseInfo.PropertyChanged += DataBasePropertyChanged;
}
}
}
...
private void DataBasePropertyChanged(object sender, PropertyChangedEventArgs e)
{
NotifyPropertyChanged(m => m.DatabaseInfo);
}
Please note that you will need to attach this listener each time that you change the DatabaseInfo property value. Also, note that if you just wanted to listen to one property, then you could have done this:
private void DataBasePropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "ServerName") NotifyPropertyChanged(m => m.DatabaseInfo);
}
private Database _DatabaseInfo = new Database();
public MyConfiguration()
{
this._DatabaseInfo.PropertyChanged += new PropertyChangedEventHandler(propChanged);
}
private void propChanged(object sender, PropertyChangedEventArgs e)
{
// Now you can update the _DatabaseInfo.DatabaseInfo property to force the property changed event to fire.
}
Refer to the documentation here
INotifyPropertyChanged.PropertyChanged event

Abstract DomainCollectionView (Entity Framework) code into its own service (MVVM Silverlight4)

I've got a VM class below that's being used to wire up a view to my ADO.NET Entity Data Model, utilizing a P_BUDGET class. This works fine, gets my data, makes everything pretty. I have about 15-20 pages that are all going to be based on the same structure as this, and the code is going to be virtually identical except for the EntityType (P_BUDGET, P_ACCOUNT, P_CIRCUIT, etc etc). I feel like there should be a way to abstract this out, but I tried, and failed miserably! I also feel like I should be able to use one view, one viewmodel, and just swap out the entities binding to the GV... I just haven't been able to find a way to variablize the type, which permeates the entire viewmodel.
Appreciate your help,
Scott
public class TestViewModel : ViewModelBase
{
private readonly ODADomainContext _context = new ODADomainContext();
private readonly DomainCollectionView<P_BUDGET> _view;
private readonly DomainCollectionViewLoader<P_BUDGET> _loader;
private readonly EntityList<P_BUDGET> _source;
private bool _isGridEnabled;
/// <summary>
/// Initializes a new instance of the TestViewModel class.
/// </summary>
public TestViewModel()
{
this._source = new EntityList<P_BUDGET>(this._context.P_BUDGETs);
this._loader = new DomainCollectionViewLoader<P_BUDGET>(
this.LoadSampleEntities,
this.OnLoadSampleEntitiesCompleted);
this._view = new DomainCollectionView<P_BUDGET>(this._loader, this._source);
INotifyCollectionChanged notifyingSortDescriptions =
(INotifyCollectionChanged)this.CollectionView.SortDescriptions;
notifyingSortDescriptions.CollectionChanged +=
(sender, e) => this._view.MoveToFirstPage();
using (this.CollectionView.DeferRefresh())
{
this._view.PageSize = 10;
this._view.MoveToFirstPage();
}
}
#region View Properties
public bool IsGridEnabled
{
get
{
return this._isGridEnabled;
}
private set
{
if (this._isGridEnabled != value)
{
this._isGridEnabled = value;
this.RaisePropertyChanged("IsGridEnabled");
}
}
}
public ICollectionView CollectionView
{
get { return this._view; }
}
#endregion
private LoadOperation<P_BUDGET> LoadSampleEntities()
{
this.IsGridEnabled = false;
return this._context.Load(
this._context.GetBudgetsQuery());
}
private void OnLoadSampleEntitiesCompleted(LoadOperation<P_BUDGET> op)
{
this.IsGridEnabled = true;
if (op.HasError)
{
// TODO: handle errors
_view.PageSize = 0;
op.MarkErrorAsHandled();
}
else if (!op.IsCanceled)
{
this._source.Source = op.Entities;
_view.PageSize = 10;
this._view.MoveToFirstPage();
if (op.TotalEntityCount != -1)
{
this._view.SetTotalItemCount(op.TotalEntityCount);
}
}
}
////public override void Cleanup()
////{
//// // Clean own resources if needed
//// base.Cleanup();
////}
}
Try something like this. This is not tested (obviously), not even complied. This also assumes that the EntityTypes (P_BUDGET, P_ACCOUNT, P_CIRCUIT etc.) are not POCOs.
public class TestViewModel<TEntity> : ViewModelBase
{
private readonly ODADomainContext _context = new ODADomainContext();
private readonly DomainCollectionView<TEntity> _view;
private readonly DomainCollectionViewLoader<TEntity> _loader;
private readonly EntityList<TEntity> _source;
private bool _isGridEnabled;
/// <summary>
/// Initializes a new instance of the TestViewModel class.
/// </summary>
public TestViewModel()
{
this._source = new EntityList<TEntity>(this._context.GetEntitySet<TEntity>);
this._loader = new DomainCollectionViewLoader<TEntity>(
this.LoadSampleEntities,
this.OnLoadSampleEntitiesCompleted);
this._view = new DomainCollectionView<TEntity>(this._loader, this._source);
INotifyCollectionChanged notifyingSortDescriptions =
(INotifyCollectionChanged)this.CollectionView.SortDescriptions;
notifyingSortDescriptions.CollectionChanged +=
(sender, e) => this._view.MoveToFirstPage();
using (this.CollectionView.DeferRefresh())
{
this._view.PageSize = 10;
this._view.MoveToFirstPage();
}
}
#region View Properties
public bool IsGridEnabled
{
get
{
return this._isGridEnabled;
}
private set
{
if (this._isGridEnabled != value)
{
this._isGridEnabled = value;
this.RaisePropertyChanged("IsGridEnabled");
}
}
}
public ICollectionView CollectionView
{
get { return this._view; }
}
#endregion
private LoadOperation<TEntity> LoadSampleEntities()
{
this.IsGridEnabled = false;
return this._context.Load(
this._context.GetBudgetsQuery());
}
private void OnLoadSampleEntitiesCompleted(LoadOperation<TEntity> op)
{
this.IsGridEnabled = true;
if (op.HasError)
{
// TODO: handle errors
_view.PageSize = 0;
op.MarkErrorAsHandled();
}
else if (!op.IsCanceled)
{
this._source.Source = op.Entities;
_view.PageSize = 10;
this._view.MoveToFirstPage();
if (op.TotalEntityCount != -1)
{
this._view.SetTotalItemCount(op.TotalEntityCount);
}
}
}
////public override void Cleanup()
////{
//// // Clean own resources if needed
//// base.Cleanup();
////}
}
// http://blog.zoolutions.se/post/2010/04/05/Generic-Repository-for-Entity-Framework-for-Pluralized-Entity-Set.aspx
public static class ObjectContextExtensions
{
internal static EntitySetBase GetEntitySet<TEntity>(this ObjectContext context)
{
EntityContainer container = context.MetadataWorkspace.GetEntityContainer(context.DefaultContainerName, DataSpace.CSpace);
Type baseType = GetBaseType(typeof(TEntity));
EntitySetBase entitySet = container.BaseEntitySets
.Where(item => item.ElementType.Name.Equals(baseType.Name))
.FirstOrDefault();
return entitySet;
}
private static Type GetBaseType(Type type)
{
var baseType = type.BaseType;
if (baseType != null && baseType != typeof(EntityObject))
{
return GetBaseType(type.BaseType);
}
return type;
}
}

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