DialogResult problem in wpf

Question

I have a window that I open a few times as a ShowDialog.

Every time I open it I use the new keyword in the first time i did:

var myWindow = new MyWindow();
myWindow.ShowDialog();

second time I open it from the MyWindow View Model class:

new MyWindow().ShowDialog();

in MyWindow code behind I have 2 events. one is when the user clcik ok and another when the user click cancel.

void OnCancel(){
  DialogResult = false;
}

void OnOk(){
  DialogResult = true;
}

The events fires from the View Model class form the ICommand Execute than bind to "ok" and "cancel" buttons of the window.

In the xaml I did this for the cancel button:

IsCancel = true;

And this for the ok button:

IsDefault = true;

in the first time that I opened the window I can set DialogResult = true, but after that when I try to set the DialogResult I've got exception "Dialofresult can set only after created window and shown as ShwDialog".

I also saw that the DialogResult is true after the first time is set to true and I think that the reason for the exception but I dont understand why is stay true if I closed the window and create a new one by using the new keyword...

Any suggestion

Thanks in advance

Edit: The problem is that once I clcik the "ok" button the DialogResult set to true and saty true and I can't set it to false.

Edit

Thanks everyone I solve the problem.

The problem was that I register to the View Model events ("ok" clicked and "cancel" clicked) and I remove the register when the user click "cancel" but not when he click "ok"...

Did you keep in mind that the Window closes after you set DialogResult and has to be re-opened? — Emiswelt, Jul 18 '11 at 13:57
this code works fine. Do you close the window after you set DialogResult = true ? — hcb, Jul 18 '11 at 13:59
@hcb I thought its close after I click "ok" or "cancel" its wrong? — Maya, Jul 18 '11 at 14:08
Where are you setting `DialogResult?` You should post more of your code so we can understand the problem. — Dan Puzey, Jul 18 '11 at 14:19

score 2 · Answer 1 · answered Jul 18 '11 at 13:58

2

Setting DialogResult closes the window, so you can't set DialogResult again

BTW, new Window().ShowDialog() returns a bool?, not a window...

answered Jul 18 '11 at 13:58

Thomas Levesque

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Can u explain? I missed somthing, why I cant set it again if I create a new window and display it as ShowDialog?. And I know its return bool?. – Maya Jul 18 '11 at 14:06
OK... could you show more code? From the code you posted, it's not very clear what the problem is – Thomas Levesque Jul 18 '11 at 14:12
And you're assigning the result to a variable named `myWindow`, that's why I assumed you thought it returned a window... – Thomas Levesque Jul 18 '11 at 14:12
@Thomas: the interesting part of `Window.DialogResult` is it doesn't make it obvious that setting it closes the window in the documentation. Also @Maya: if you set a button as `IsCancel` it will automatically set `DialogResult` to false, which may be why you're receiving the exception. – user7116 Jul 18 '11 at 14:32
@sixlettervariables, as a matter of fact, `DialogResult` is *not* set automatically to false; it was the case in WinForms, but in WPF you have to set it manually. @Maya, sorry, I really don't know what is causing the problem... – Thomas Levesque Jul 18 '11 at 14:35
@Thomas: [MSDN](http://msdn.microsoft.com/en-us/library/system.windows.window.dialogresult.aspx) "By default, a dialog box is canceled when a user does one of the following: Presses *ALT+F4*; Clicks the Close button; Selects Close from the System menu. In all of these cases, `DialogResult` is false by default. A dialog box typically provides a special button to cancel a dialog, which is the button whose `IsCancel` property is set to true...will automatically close a window when either it is pressed, or when the ESC key is pressed. In either of these cases, `DialogResult` remains false." – user7116 Jul 18 '11 at 14:38
@sixlettervariables IsCancel = true in my "cancel" button but the exception throw after I clicked "ok" – Maya Jul 18 '11 at 14:41
@Maya: if you put a breakpoint on `DialogResult = true;` how many times is it hit? – user7116 Jul 18 '11 at 14:42
@sixlettervariables every time I clcik "ok". in the first time the DialogResult is null but after that is true. with the "cancel" button i think everything work fine. – Maya Jul 18 '11 at 14:45
@sixlettervariables now I saw that if I click the ok button and that clcik the cancel I get the exception becuase the DialogResult already set to true – Maya Jul 18 '11 at 14:51
@sixlettervariables, my mistake, I misremembered – Thomas Levesque Jul 18 '11 at 15:03

score 1 · Answer 2 · answered Jul 18 '11 at 14:04

1

I dont understand why is stay true if I closed the window and create a new one by using the new keyword...

Because your intializing a new Window. It returns True because as you already explained the first time it does.

answered Jul 18 '11 at 14:04

Security Hound

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but the previous window is disposed so why when I created a new one is DialogResult is true and not null? – Maya Jul 18 '11 at 15:08

DialogResult problem in wpf

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