I have a WinForms application that checks for pending changes whenever the user hits the cancel button. If there are pending changes, I prompt the user to see if they are sure they wish to cancel. If they do, I close the form. If not, I just return. However, the form is closing anyways. After some debugging, I realized it was because this particular button is set to the form's CancelButton, so clicking it caused the form to close. To verify, I removed the CancelButton property, but the behavior persisted.
How can I prevent this automatic closing? Here is my event handler code:
private void closeButton_Click(object sender, EventArgs e)
{
DialogResult dr = DialogResult.Yes;
if (changesMade)
{
dr = MessageBoxEx.Show(this, "Are you sure you wish to disregard the changes made?", "Changes Made", MessageBoxButtons.YesNo);
}
if (dr == DialogResult.Yes)
{
Close();
}
else
{
//TODO:
}
}
In the above code, the form should only close if there are no changes made, or if the user chose to disregard them. I made changes, and clicked 'No' to the DialogBox, but the form still closed. With and without the button set as the form's CancelButton.
Just set the property DialogResult of the form to the enum DialogResult.None
....
if (dr == DialogResult.Yes)
{
Close();
}
else
{
this.DialogResult = DialogResult.None;
}
or simply:
if (dr != DialogResult.Yes)
this.DialogResult = DialogResult.None;
The form closes automatically because the property DialogResult of the button is not set to DialogResult.None in the Forms Designer. In this scenario, the WinForms engine takes that value and assign it to the DialogResult property of the whole form causing it to automatically close. This is usually used in the calling code of the form to distinguish between a Confirm and a Cancel button
In the example below suppose that on the frmCustomers there are two buttons, one with the DialogResult property set to DialogResult.OK and another set to DialogResult.Cancel. Now if the user hits the OK button you know, in the calling code what to do with the inputs for your new customer
using(frmCustomers f = new frmCustomers())
{
if(f.ShowDialog() == DialogResult.OK)
{
// Execute code to save a customer
}
}
Following up on my comment, this is what I do for an internal tool I wrote recently:
private void Form_FormClosing(object sender, FormClosingEventArgs e)
{
e.Cancel = !PromptUnsavedChanges();
}
private bool PromptUnsavedChanges()
{
if (HasFormChanged()) //checks if form is different from the DB
{
DialogResult dr = MessageBox.Show("You have unsaved changes. Would you like to save them?", "Unsaved Changes", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question);
if (dr == System.Windows.Forms.DialogResult.Yes)
tsmiSave_Click(null, null); // Saves the data
else if (dr == System.Windows.Forms.DialogResult.Cancel)
return false; // Cancel the closure of the form, but don't save either
}
return true; // Close the form
}
The logic could probably cleaned up from a readability point of view, now that I'm looking at it months later. But it certainly works.
With this you simply just call this.Close(); in your button click event. Then that event is what handles the prompting and decides if it should actually close or not.
Related
I have a button for exiting the form and this is the code
DialogResult dialogResult = MessageBox.Show("Are you sure you want to exit?", "Exit Program?", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.No)
{
}
else
{
Application.Exit();
}
I tried using debugger mode, and after I click yes, it goes through Application.Exit() and then fires up the FormClosing event then running the same dialog.
I also tried deleting the code in FormClosing event so it only has Application.Exit() but using Alt+F4 or clicking the X button will exit the application automatically.
My question is how can I question the user if he wants to exit the program but not firing the dialog twice?
Thanks in advance, and I'm letting you all know I'm just a beginner and this is my biggest project so I want to make this great.
Here's an example. It only asks for confirmation if the close was initiated by the user - you probably don't want a MessageBox popping up when Windows is restarting.
private void form_FormClosing(object sender, FormClosingEventArgs e)
{
if (e.CloseReason == CloseReason.UserClosing)
{
DialogResult dialogResult = MessageBox.Show("Are you sure you want to exit?", "Exit Program?", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.Yes)
{
Application.Exit();
}
}
else
{
// Cancel the close
e.Cancel = true;
}
}
There are two ways to achieve this.
By unsubscribe the even on button click
As suggested in stuartd's answer, checking reason of closing (but there is a problem in his answer so adding this approach too with fix, so it will help future people.)
I am assuming, As you need this confirmation in both cases, button click and 'x' button click, you have put the same code in both handler.
Approach one
In the handler of button click, while you are asking for user confirmation and if user is clicking 'yes'.
Before the line,
Application.Exit();
you should unsubscribe the Form closing event. By doing this, It must not raise form closing event while performing Application.Exit()
assuming your form is MainForm and event is MainForm_Closing, it would look like,
private void btnClose_Click(object sender, EventArgs e)
{
DialogResult dialogResult = MessageBox.Show("Are you sure you want to exit?", "Exit Program?", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.Yes)
{
this.FormClosing -= MainForm_FormClosing;
Application.Exit();
}
}
so it will not raise form closing event while performing Application.Exit() and thus your problem will be solved.
Approach Two
As stuartd has suggested (which is more cleaner way according to me. +1 for that), you can check for form closing reason in Form Closing event handler.
Note that there is a little problem (bug) in his sample code [which you have already accepted as an answer!!]. After clicking 'x' button or Alt+F4 by mistake; if user clicks on 'No' on the confirmation message, then too form is being closed because there is no handling for else condition. Proper solution should be like below.
private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
{
if (e.CloseReason == CloseReason.UserClosing)
{
DialogResult dialogResult = MessageBox.Show("Are you sure you want to exit?", "Exit Program?", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.Yes)
Application.Exit();
else
e.Cancel = true; //stopping Form Close perocess.
}
}
I'm writing a WinForm desktop application. In the main form, the user clicks on a button which calls another form for the user to submit data to. At the end of this submission process, the user clicks on a "Save" menu item to close the subform.
This is the code for the subform calling:
private void btnSubmit_Click(object sender, EventArgs e)
{
// code for setting myFormArgs
myForm form = new myForm(myFormArgs);
form.ShowDialog();
// the user clicked "Yes" on a "Confirm" MessageBox
if (form.DialogResult == DialogResult.Yes)
{
// code for saving data
form.Dispose();
}
}
and this is the code for the "Save" menu item in the subform:
private void menuSave_Click(object sender, EventArgs e)
{
string message, title;
MessageBoxIcon icon;
MessageBoxButtons buttons;
if(DataSubmitted)
{
if(ValidData)
{
message = "Confirm?";
title = "Select an action";
icon = MessageBoxIcon.Information;
buttons = MessageBoxButtons.YesNo;
}
else
{
message = "Incomplete data";
title = "Error";
icon = MessageBoxIcon.Error;
buttons = MessageBoxButtons.OK;
}
}
else
{
message = "No data submitted";
title = "Error";
icon = MessageBoxIcon.Error;
buttons = MessageBoxButtons.OK;
}
this.DialogResult = MessageBox.Show(message, title, buttons, icon);
if (this.DialogResult == DialogResult.Yes) this.Close();
else this.OnFormClosing(new FormClosingEventArgs(CloseReason.None, true));
}
The problem is that the code will always get back to the calling method, thus closing (maybe just hiding?) the sub-form, even if the this.Close() method isn't called.
Thanks in advance.
you should not make a new event instance, those are things you would want to avoid
instead try:
DialogResult dialogResult = MessageBox.Show("Sure", "Some Title",
MessageBoxButtons.YesNo);
if(dialogResult == DialogResult.Yes)
{
Close();
}
Events are supposed to occur automatically, so 'OnFormClosing' will raise when the form will close.
also i recommend to use this.Close instead of Dispose
Form.Close() sends the proper Windows messages to shut down the win32 window. During that process, if the form was not shown modally, Dispose is called on the form. Disposing the form frees up the unmanaged resources that the form is holding onto.
for more organized code,
try making an instance of the form from the main form
and handle the dialog result like this:
using (SubForm form = new SubForm())
{
DialogResult dr = form.ShowDialog();
if(dr == DialogResult.Yes)
{
string studdToSave= form.StuffToSave;
SaveToFile(studdToSave);
}
}
I find it strange that you want to close the form when the user just wants to save the data. :)
Save should not close your form.
When you close the form, you should verify if there are unsaved changes.
If there are, ask the user the question if he wants to save his changes before closing and offer him the options Yes, No and Cancel, where Cancel means 'cancel closing the form'.
Depending on wether the user clicked Yes or No, you should or shouldn't save the changes.
If the user clicked cancel, you should cancel closing the form by having an event for the FormClosing event. This event allows you to cancel closing the form.
private void btnClose_Click(object sender, EventArgs e)
{
if (unsavedChanges)
{
var result = MessageBox.Show("Save changes?", "unsaved changes", MessageBoxButtons.YesNoCancel);
if (result == DialogResult.Yes)
{
SaveChanges();
}
if (result == DialogResult.Cancel)
{
cancelClose = true;
}
this.Close();
}
}
private void Form2_FormClosing(object sender, FormClosingEventArgs e)
{
e.Cancel = cancelClose;
cancelClose = false;
}
The code above is usefull when 'Form2' is not a modal form.
If you want Form2 to be shown modal, the code above will work as well. However, you can also use the DialogResult proprety of the Form in that case:
private void btnClose_Click(object sender, EventArgs e)
{
if (unsavedChanges)
{
var result = MessageBox.Show("Save changes?", "unsaved changes", MessageBoxButtons.YesNoCancel);
if (result == DialogResult.Yes)
{
SaveChanges();
}
if (result == DialogResult.Cancel)
{
result = DialogResult.None;
}
this.DialogResult = result;
}
}
I am unable to determine why the following code fails to save changes to database during FormClosing event:
private void frmClient_FormClosing(object sender, FormClosingEventArgs e)
{
if (bAreChanges)
{
DialogResult dialogResult = MessageBox.Show("Do you wish to save the changes to the database?",
"Confirmation", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question);
if (dialogResult == DialogResult.Yes)
{
using (var context = new SomeEntities()) {
var value = "abc";
context.sometable.Add(new sometable() {somefield = value} );
context.SaveChanges();
//the same exact code works when executed from a simple button click that is placed on this form.
}
this.Validate(); // even added this line as suggested in another Stackoverflow question
}
else if (dialogResult == DialogResult.No)
{
}
else
{
e.Cancel = true;
}
}
}
Perhaps some part of SaveChanges() is asynchronous and therefore the Form disposes before the database operation is executed?
Edit: This is a child form, not the main form - the application keeps running after this form is closed. If this is somehow relevant.
Putting this.Validate() before the database operations made it work. I would, however, like to know why is that relevant in this case.
i am pretty newbie for coding. Here is i am having a problem:
private void pano_FormClosing(object sender, FormClosingEventArgs e)
{
DialogResult dialog = MessageBox.Show("Uygulamadan çıkış yapmak istediğinizden emin misiniz?", "Çıkış", MessageBoxButtons.YesNo);
if (dialog == DialogResult.Yes)
{
Application.Exit();
}
else if (dialog == DialogResult.No)
{
e.Cancel = true;
}
My purpose with this code block to ask user "are sure to quit" but unfortunetly when i close the application, i got notification window for 3 times? Is there any idea why thats happening or any solution?
Thanks a lot.
Nuri.
Firstly, as Steve pointed out, remove the 'Yes' part - if not explicitly canceled, the event will close that form as a result of clicking.
Now, for the problem of yours. Seems like your alert is called twice. I was able to solve that easily by making a static bool close_alert_shown, and when the first alert is shown, set it to true so that the next alert won't pop up.
Final code looks like that:
if (close_alert_shown) return;
close_alert_shown = true;
DialogResult dialog = MessageBox.Show("Uygulamadan çıkış yapmak istediğinizden emin misiniz?", "Çıkış", MessageBoxButtons.YesNo);
if (dialog == DialogResult.No)
{
e.Cancel = true;
close_alert_shown = false;
}
And on the top of the form (before the public Form1() contructor line):
static bool close_alert_shown = false;
What i suspect is when application is exiting, it is again calling form closing since we have subscribed for that event. I assume, simple fix would be unsubscribe from the event before calling exit.
this.FormClosing-=Form1_FormClosing;
Application.Exit();
I seem to be having difficult in having a Dialog box pop up and function properly when a use clicks the red "X" button in the top right corner of the application. I can make the Dialog appear to ask if they really want to close the application, but regardless of what they click, it will close the form. The code I have is as follows;
private void Main_FormClosing(object sender, FormClosingEventArgs e)
{
DialogResult dr = MessageBox.Show("Are you sure want to close?", "Close Program", MessageBoxButtons.OKCancel);
if (dr == DialogResult.Cancel)
{
e.Cancel = false;
}
}
I have also tried instead of e.Cancel to check if dr is equal to ok but the same situation happens.
Any thoughts?
e.Cancel = true; cancels the action. and it is by default false. you are not setting it to true anywhere. try this.
private void Main_FormClosing(object sender, FormClosingEventArgs e)
{
DialogResult dr = MessageBox.Show("Are you sure want to close?", "Close Program", MessageBoxButtons.OKCancel);
if (dr == DialogResult.Cancel)
{
e.Cancel = true;
}
}
oneliner:
e.Cancel = MessageBox.Show("Are you sure want to close?", "Close Program", MessageBoxButtons.OKCancel) == DialogResult.Cancel;
The issue is that you are never setting e.Cancel to true. I would modify your message box to show Yes and No buttons as I feel it makes it clearer to the user and then I would just set e.Cancel to true if the user chooses No.
private void Main_FormClosing(object sender, FormClosingEventArgs e)
{
DialogResult dr = MessageBox.Show("Are you sure want to close?", "Close Program", MessageBoxButtons.YesNo);
e.Cancel = dr == DialogResult.No;
}
The Closing event occurs as the form is being closed. When a form is closed, all resources created within the object are released and the form is disposed. If you cancel this event, the form remains opened. To cancel the closure of a form, set the Cancel property of the CancelEventArgs passed to your event handler to true.
e.Cancel = true;