Is it possible to know if any of the textbox values have changed in the application.
I have around 30 textboxes and I want to run a part of code only if, any of the textboxes value has changed out of the 30. Is there a way I can know that.
Each text box will raise an event TextChanged when it's contents have changed. However, that requires you to subscribe to each and every event.
The good news is that you can subscribe to the event with the same method multiple times. The handler has a parameter sender which you can use to determine which of your 30 text boxes has actually raised the event.
You can also use the GotFocus and LostFocus events to keep track of actual changes. You would need to store the original value on GotFocus and then compare to the current value on LostFocus. This gets round the problem of two TextChanged events cancelling each other out.
You can assign an event handler to each of the TextBox's TextChanged events. All of them can be assigned to the same event handler in code. Then you'll know when the text changes. You can set a boolean flag field in your class to record that a change occurred.
This is perhaps on the rough and ready side, but I did it this way.
In the constructor, I created
bool bChanged = false;
In the TextChanged event handler of each control (actually same for each), I put
bChanged = true;
When appropriate, I could do some processing, and set bChanged back to false.
You can also just do this:
In your Constructor:
MyTextBox.TextChanged += new TextChangedEventHandler( TextChanged );
And Then this Method:
private void TextChanged(object Sender, TextChangedEventArgs e){
//Do something
}
try this. Add this code to the load/constructor. no need to specify the event in the XAML explicitly
this.AddHandler(TextBox.TextChangedEvent, new TextChangedEventHandler(TextChanged));
private void TextChanged(object Sender, TextChangedEventArgs e)
{
//ToDO (use sender to identify the actuale text from where it fired }
}
Related
I assign the event using:
numTextBox.TextInput += NumTextBox_TextInput;
And handle it with this method:
private void NumTextBox_TextInput(object sender, System.Windows.Input.TextCompositionEventArgs e)
{
Console.WriteLine(e.Text);
}
I have a break at Console.WriteLine. Typing into the TextBox does not force the break or write to console. Is there a better way for me to handle the event? Or is there a problem in my code that I'm missing?
According to MS documentation, TextInput event occurs when the textbox gets text in a device-independent manner. Use the TextChanged event instead.
Read: https://learn.microsoft.com/en-us/dotnet/desktop/wpf/controls/how-to-detect-when-text-in-a-textbox-has-changed?view=netframeworkdesktop-4.8
Other than that, as you're handling an event raised from an UI, using Console.WriteLine() would be useless cause you won't be able to see the output in your main form.
Instead use another text control that'll display the text or simply use
MessageBox.Show("Text = " + ((TextBox)sender).Text);.
I have in my project 5 text boxes.
Every TextBox should accept only digits.
For that I created a function which takes not prepared text and returns the proper one.
Now I'm wondering if there is any simpler way to perform this action on every TextBox, on every TextChanged event without repeating almost same code?
private void TextGoldPack_TextChanged(object sender, EventArgs e)
{
(sender as TextBox).Text = Only_digits((sender as TextBox).Text);
}
private void TextGoldTake_TextChanged(object sender, EventArgs e)
{
//repeat here and on every _TextChanged event
}
If I'm understanding you correctly, just because it's named TextGoldTake_TextChanged, doesn't mean that's the only textbox that can use that code. On the events tab, you can set the TextChanged function for all you textboxes to lead to that function. If it helps, rename it something that doesn't sound textbox-specific such as TextChanged.
Change all the TextBoxes to refer this method upon TextChanged.
Use the sender property to get the actual caller TextBox.
I use the Layout Event Handler in order to set the focus to a specific field. So everytime the Layout event occurs, the focus will be set to that field.
My problem is that when I make something visible/invisible, the focus will be set again to this specific field which I don't want.
How to avoid that?
Is there a way to say "skip the Layout Event Handler next time" ?
or should I use another Event Handler instead of the Layout one?
I just want it to be set the first time, but the Load event does not seems to work as expected.
Code for Load event handler:
in the Designer.cs
private void InitializeComponent()
{
// other stuff automatically generated by windows
this.Load += new System.EventHandler(this.myControl_Load);
// other stuff automatically generated by windows
}
and in myControl.cs:
private void myControl_Layout(object sender, LayoutEventArgs e)
{
this.myTimeEdit.Focus();
}
From what I gather, you need to focus a particular control when a form is shown for the first time. First, you can try to set the TabIndex property to 0. In this case, this control will be focused on the first form showing.
Try also to focus the control on the Form.Shown event instead of the Load event.
You can use LayoutEventArgs.AffectedProperty property. Just check if its value is set to "Visible":
private void myControl_Layout(object sender, LayoutEventArgs e)
{
if (e.AffectedProperty == "Visible")
return;
this.myTimeEdit.Focus();
}
In my C# Windows form MyForm I have some TextBoxes.
In these TextBoxes, we have to detect if the TextChanged event occurs,
if there're changes in these TextBoxes and click close button, it will ask if we want to cancel the changes when we close the form.
However, when I run the MyForm, I can't know text change for each textbox caused by user typing for without textchanged event property.
But I am thinking how do I make the TextBox's TextChanged know the
event cuased by user typing without textchanged event?
Thanks for help.
Sorry for my English.
There is no (decent) way of knowing what's typed without a TextChanged or a Leave event.
You need to use one of these events to get the typed content. Doing this enable you to set a "dirty" flag that you can check at close and clear at save.
Comparing old and new value has no point without this cause you won't know what the value should be set to without knowing something was changed.
With one exception: If your original data came from a database you could use the compare old/new approach as you would compare the textbox of that which came from the database.
Update:
Addressing this comment:
"Because Myform have many textboxes and if no text change ,this will
not display the confirm message.If I catch textchanged event for all
textboxes, this is so many code."
You can use a common handler to collect the changes for all textboxes in one single method. Use the sender object (cast it to Textbox) to identify which textbox is changed, if needed, or simply set a dirty flag for whatever textbox has a change.
bool isDirty = false;
void SomeInitMethod() //ie. Form_Load
{
textbox1.TextChanged += new EventHandler(DirtyTextChange);
textbox2.TextChanged += new EventHandler(DirtyTextChange);
textbox3.TextChanged += new EventHandler(DirtyTextChange);
//...etc
}
void DirtyTextChange(object sender, EventArgs e)
{
isDirty = true;
}
void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
if (isDirty) {
//ask user
}
}
// to clear
void Save()
{
SaveMyDataMethod();
isDirty = false;
}
If you have a lot of textboxes in the form loop through the forms control collection and use typeof to address the textboxes. If you have textboxes requiring different approaches use the Tag property of the textbox to distinguish.
A possible approach is using the timer. Have a timer that ticks every 1000 ms (say) and checks the textBox.Text.
A second possible approach is overriding WndProc for the textbox (by inheriting a new class) and handling the change text message. This would be the same as overriding TextBox.OnTextChanged.
Why dont you use a timer which will check after a few intervals if the textboxes do contain any text
I have this simple code, where when the user leaves the TextBox control, TreeView gets focused:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
this.treeView1.Nodes.Add("A");
this.treeView1.Nodes[0].Nodes.Add("A.A");
this.treeView1.Nodes.Add("B");
this.treeView1.Nodes[0].Nodes.Add("B.A");
}
private void textBox1_Leave(object sender, EventArgs e)
{
System.Diagnostics.Debug.WriteLine("Leave..");
this.treeView1.Focus();
}
}
If we execute this code the Leave event is fired twice:
Leave..
Leave..
But if we set focus to other control, only one Leave event is fired.
Is that a problem of the TreeView? Do you know any workaround? Should we report this to Microsoft?
Thanks,
RG
this.treeView1.Focus();
Do not use the Focus() method in an event handler that's called because of a focusing event, like Leave. If you need to prevent a focus change then use the Validating event instead. Setting e.Cancel = true stops it.
But do note that this isn't very logical to do so for a TreeView, there isn't anything the user can do to alter the state of the control. You'll trap the user. Maybe that was the intention, do make sure the user can still close the window. If not then you might need the FormClosing event to force e.Cancel back to false.
Given that there is no code there to wire up the event I'm guessing you did it from the designer which means a line of code such as
textBox1.Leave += new EventHandler(textBox1_Leave);
will have been added to the Form1.designer.cs, check this file to ensure the line doesn't exist more than once as for each time this line is run you will get an event trigger, so if you run the line 3 times the Leave event will fire 3 times when you leave the textbox!
HTH
OneShot