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I have a PropertyGrid in an application. I have a problem with a functionallity reverting to a old value if I detect the new value as invalid.
Here is some short information abut the PropertyGrid:
* There are properties which are strings.
* I cannot allow an empty string for any properties.
* I want a revert functionallity to revert to the old value.
* The PropertyGrid is localized so the DisplayName of each property is NOT the same as the name of the property.
With the event
PropertyGrid.PropertyValuechanged I can get what property was changed.
The event's callback pass a
PropertyCalueChangedEventArgs object which I use revert with these properties:
PropertyValueChangedEventArgs.OldValue
PropertyValueChangedEventArgs.ChangedItem.Label
This gets the old value and the DisplayName of the property which was changed.
Here is the class I display in the PropertyGrid:
public class Person
{
public Person()
{
}
public string FirtName
{
get;
set;
}
public string LastName
{
get;
set;
}
public int Age
{
get;
set;
}
}
I use this code to revert back to the old value:
private void Revert(object obj, string name, string oldValue)
{
Type type = obj.GetType();
PropertyInfo property = type.GetProperty(name);
property.SetValue(obj, oldValue, null);
}
The PropertyGrid.PropertyValuechanged event has this callback:
void propertyGrid1_PropertyValueChanged(object s, PropertyValueChangedEventArgs e)
{
if (e.ChangedItem.Value is string && e.ChangedItem.Value.ToString() == "")
{
Revert(propertyGrid1.SelectedObject, e.ChangedItem.Label, e.OldValue.ToString());
}
}
The IF-satement will detect any new values which is an empty string.
Here is the problem
As the DisplayName of each property in the PropertyGrid is localized the PropertyValueChangedEventArgs.ChangedItem.Label will contain the localized name and not the actual name of the property.
For instance the Person.FirstName property will be localized to "First name". Therefore the Revert() method will try to get a property called "First name" as name instead of "FirstName". This of course will not work.
I have search for ways to get the actual property which was changed. It seems almost impossible...
But with the debug in Visual Studio I can see that the
PropertyValueChangedEventArgs.ChangedItem
is a base class of the internal .Net Framework class
System.Windows.Forms.PropertyGridInternal.PropertyDescriptorGridEntry Read more about it here[^]
This class contain a property called "PropertyName" which is the exact name as the property's actual name!!!
With reflection I have tried to get this class by trying:
void propertyGrid1_PropertyValueChanged(object s, PropertyValueChangedEventArgs e)
{
if (e.ChangedItem.Value.ToString() == "")
{
GridItem item = e.ChangedItem;
object[] objs = item.GetType().GetFields(BindingFlags.Instance | BindingFlags.NonPublic);
Console.WriteLine(objs.Length);
object o = item.GetType().GetMember("parentPE");
}
}
In the object[] array it seems to be a field which is name "parentPE". This is of type:
System.Windows.Forms.PropertyGridInternal.GridEntry
I have no luck getting the object 
Is there a solution for this?
Note:
I'm aware I should not use reflection to access internal classes of the .NET framework. But I cannot see any other solution in the moment. I'm all for any other solutions.
Best regards,
/Steffe
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The ChangedItem property is declared as the public GridItem type[^].
That type exposes a property called PropertyDescriptor[^], which returns a PropertyDescriptor instance[^].
The PropertyDescriptor class has a property called Name[^], which returns the name of the property without any localization.
void propertyGrid1_PropertyValueChanged(object s, PropertyValueChangedEventArgs e)
{
PropertyDescriptor theProperty = e.PropertyDescriptor;
if (theProperty != null)
{
string propertyName = theProperty.Name;
...
}
}
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Thank you very very much!
/Steffe
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Mc_Topaz wrote: * I cannot allow an empty string for any properties.
* I want a revert
functionallity to revert to the old value.
This is easily done in each of your properties Set code. Just check the value of the incoming string and don't set the new value in the backing field of the property if it's empty or null.
You don't need any of the PropertyGrid code to do this.
Localized property names don't even come into play.
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Mc_Topaz wrote: But I cannot see any other solution in the moment.
To add to the other comments; if it depends on internals, then it is not a solution - it's a dirty hack that may stop working without any warning.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
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Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Eddy Vluggen wrote: may stop working
Then again it might not. 
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..only if you see "hope and pray" as a viable strategy 
Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
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Nice to see Luc is still remembered!
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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I am new to this control and was given task on this i don't know how to bind data or document to this document viewer please help me anyone.
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I've never heard of it. Where's the documentation?
There are only 10 types of people in the world, those who understand binary and those who don't.
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If you've got questions about a specific library, your best place to ask is in a forum dedicated to that library.
I doubt any of the regulars here has ever heard of the control you're talking about so it's very unlikely you're ever going to get an answer on it here.
Wow! Look what I found: A Support tab[^] that has Support Forums, Product Documentation, Getting Started Tutorials and Programmer's Guide and Reference!
All you had to do was go to their website and you would have found exactly what you're looking for, plus product focused support, if you just put the tiniest bit of effort into looking for it.
modified 11-Sep-14 19:04pm.
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Oh, he's on my Watch List big time now. 
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Yeah, after looking at this guys history, I see what you mean.
Has this putz ever heard of Google?
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I have to start timer at 12AM daily. It has to execute 4 items i have with 15min interval
i.e, item1 should be executed @12, item2 @12 15 and so on
i have written below code:
To start timer @12Am :-
private void SetTimerValue()
{
//// trigger the event at 12 AM.
DateTime requiredTime = DateTime.Today.AddHours(0).AddMinutes(00);
if (DateTime.Now > requiredTime)
{
requiredTime = requiredTime.AddDays(1);
}
TimeSpan periodTS = requiredTime - DateTime.Now;
myTimer = new System.Threading.Timer(new TimerCallback(TimerAction), null, 0, (long)periodTS.TotalMilliseconds);
}
In TimerAction i have 4 items which has to be called @ 15min interval
public void TimerAction(object e)
{
var collection = new List<string> { "item1", "item2", "item3", item4" };
// When timer is 12am, execute item1
// When timer is 12 15am, execute item2
// When timer is 12 30am, execute item3
// When timer is 12 45am, execute item4
}
My question is :
1. Can i create seperate timer inside TimerAction method?
2. How should i loop and execute all these 4 items?
3. Is there any better approach?. Please guide me to do this.
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Avoid generating new timers at all - they are a scarce resource, so you should try to keep them to a minimum.
A much, much better approach is to use a single timer, that has a smaller interval: 15 minutes, or maybe five minutes.
You then check the current DateTime against the main trigger time - 12 AM - and set a new time for the next task - 12:15.
When you hit (or pass) that time, you execute your task, and set the next time to 12:30, and so on.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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how to stop the timer after 12 45. how can i check each item at specific time...can u pls show me in code
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Member 11074115 wrote: how to stop the timer after 12 45
Easy - set the initial timer to tomorrow 12 AM.
That way the whole sequence starts again the next day (assuming the program is still running)
Member 11074115 wrote: how can i check each item at specific time...can u pls show me in code
Oh, come on! 
You know how to add 15 minutes to a DateTime - or you should.
You know how to fetch the current date and time.
And you know how to compare two DateTime values.
So what part of this is complicated?
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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i have already written code to trigger @12, but in TimerAction i am not able to get the timer time. How to fetch that value so i can check for each item.
Here am setting timer
private void SetTimerValue()
{
//// trigger the event at 12 AM.
DateTime requiredTime = DateTime.Today.AddHours(0).AddMinutes(00);
if (DateTime.Now > requiredTime)
{
requiredTime = requiredTime.AddDays(1);
}
TimeSpan periodTS = requiredTime - DateTime.Now;
myTimer = new System.Threading.Timer(new TimerCallback(TimerAction), null, 0, (long)periodTS.TotalMilliseconds);
}
But in TimerAction i shud loop items and set interval....i dono how to do that..wer shud i set interval
ublic void TimerAction(object e)
{
var collection = new List<string> { "item1", "item2", "item3", "item4" };
// When timer is 12am, execute item1
// When timer is 12 15am, execute item2
// When timer is 12 30am, execute item3
// When timer is 12 45am, execute item4
}
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Don't.
Do this:
private enum Action
{
Disabled, Item1, Item2, Item3, Item4
}
private DateTime doAfter = DateTime.MaxValue;
private Action action = Action.Disabled;
This gives you the framework you need.
Then, set up and start the timer:
private void SetTimer()
{
Timer timer = new Timer();
timer.Interval = 1000 * 60 * 5;
timer.Tick += new EventHandler(timer_Tick);
timer.Start();
action = Action.Item1;
doAfter = DateTime.Now.Date.AddDays(1);
}And then handle the Tick:
private void timer_Tick(object sender, EventArgs e)
{
if (DateTime.Now >= doAfter)
{
switch (action)
{
case Action.Item1:
action = Action.Item2;
doAfter = doAfter.AddMinutes(15);
break;
...
case Action.Item4:
action = Action.Item1;
doAfter = DateTime.Now.Date.AddDays(1);
break;
}
}
}
And it handles it all for you.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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i have written below code, but it never triggers OnTimedEvent event. i should debug and test the code inside OnTimedEvent. How should i do this
private void SetTimer(TimeSpan interval)
{
timer = new System.Timers.Timer();
timer.Interval = 1000 * 60 * 5; // 5 minutes
timer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
timer.Start();
}
private void OnTimedEvent(object source, ElapsedEventArgs e)
{
// want to debug and test the code written here.
}
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How can I implement this so it works properly?
Main thread creates an instance of Foo(). Foo() has a method Go(). I want Go() to be fire-and-forget, but I want ALL Go()'s to run before the process is allowed to exit, but I want that all encapsulated in Foo(). So...
I want:
main()
{
Foo f = new Foo();
for (int i = 0; i <= 200; i++)
f.Go();
}
That's all that the caller should do. No waits, no sleeps, no usings, nothing. Assuming thats possible.
so I tried using a queue where Go() adds an item to the queue and the Foo constructor spawns a thread that monitors the queue.
So it does work, but the worker thread is dying before it's done.
I tried putting a .Wait() on the task in ~Foo(), but the process still exits.
Also tried old school Thread, but then it never even seems to hit the ~Foo(). The main thread is now waiting on the worker thread to finish, but the worker thread is supposed to run for the life of Foo(), I would have expected main() to determine and try to kill Foo() and have it block in the finalizer???
modified 10-Sep-14 16:34pm.
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No, I want the app to NOT exit after spawning off threads...
1) main thread creates instance of Foo()
2) for (1..1000) Foo.Go() should be a fire and forget unit of work
3) main thread "exits", but only unit of work 1..30 were processed because the main thread exited too fast
What I want instead is:
1) main thread creates instance of Foo()
2) for (1..1000) Foo.Go() should be a fire and forget unit of work
3) main thread "exits", BUT "PROCESS HANGS" until all 1000 units of work are completed
I know I can do this with a .Join in the main thread, but as I said in my original post is that Foo() is its own man. If it wants to "block the process from exiting" until all the work is completed, it should do so without the main threads assistance.
Seems like when *Tasks* are running, they don't block the process from exiting
Seems like when a *Thread* object is running, it blocks the process from exiting
I kind of got something working, but I'm not super happy with it.
I kick off a Thread so the process is blocked from exiting... the background thread does a BlockingCollection.Take with a cancellation token. If the cancellation token is set, it exits the background thread.
Meanwhile, I also kick off a main thread watch dog task that checks if the main thread has exited and if it does, AND the queue is empty it sets the cancellation token so the background thread can exit.
It does have the behavior I want, but I'm not really liking this part:
Thread threadCurrent = Thread.CurrentThread;
Task.Run(() =>
{
if (System.Diagnostics.Debugger.IsAttached)
threadCurrent.Join();
Console.WriteLine("EXITED");
while (_queueLogEntries.Count > 0)
{
Thread.Sleep(100);
}
Console.WriteLine("EXITED2");
_cts.Cancel();
});
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