I'm trying to do a validation wherein if a checkbox has been ticked, the corresponding textbox would no longer be in ReadOnly mode and should not be empty. For example, if I checked CheckBox1, if TextBox1 did not have any input, a MessageBox would pop up to say that "Please fill up the entire form!". Else, it would display "Done!".
This is what I have so far:
if ((CheckBox1.Checked && TextBox1.Text == "")
|| (CheckBox2.Checked && TextBox2.Text == ""))
MessageBox.Show("Please fill up the entire form!");
else if (CheckBox1.Checked && TextBox1.Text != "")
MessageBox.Show("Done!");
else if (CheckBox2.Checked && TextBox2.Text != "")
MessageBox.Show("Done!");
I've made a couple of checkboxes/textboxes that would require this validation and I find that it gets kind of lengthy so I was wondering if there's a simpler/better approach.
(not sure if relevant) Note: I got the toggling the ReadOnly mode when the CheckChanged event is triggered part down
There could be some enhancements for your code, for example:
You can use this criteria !textBox.ReadOnly && string.IsNullOrEmpty(textBox.Text) rather than what you have.
You can avoid using those else if parts and just return from the method if there is a validation error and just put the code after the validation block.
A better solution - Using Validating Event
But I'd rather to change the whole style of validation and use Validating event of those TextBox controls. To do so, you need to follow these instructions:
1) Set AutoValidate property of form to EnableAllowFocusChange in design mode or using code in Load event of form.
2) Handle Validating event of all TextBox controls using single a method and set e.Cancel = true; when there is validation error:
private void textBox_Validating(object sender, CancelEventArgs e)
{
var textBox = (TextBox)sender;
if (!textBox.ReadOnly && string.IsNullOrEmpty(textBox.Text))
e.Cancel = true;
}
3) In the save button of your form, using ValidateChildren method of the form, check if there is any validation error, show a message, otherwise do what the button is supposed to do:
private void button1_Click(object sender, EventArgs e)
{
if (!this.ValidateChildren())
MessageBox.Show("Please correct validation errors.")
else
MessageBox.Show("Done!")
}
Note
To read more about validation options in Windows Forms, take a look at this post:
Validating user input / Give .NET controls status OK or NOK
Also if you want to enhance the user experience by showing a validation error/icon near the control using an ErrorProvider, take a look at this post:
Validation using Validating event and ErrorProvider - Show Error Summary
Related
I have a winforms program containing a RichTextBox.
The user inputs the text into the RichTextBox.
I wish to receive the input through keyboard events and not through textBox1.Text property, validate the string and only display it in the RichTextBox later.
How can I prevent the RichTextBox from displaying the input text by the user, even though the user inputs the text into the RichTextBox?
The RichTextBox is selected and has focus.
I am sorry. I just wanted to simplify the issue and therefore I neglected to mention that it is not a TextBox but a RichTextBox. It turns out that it matters, as the proposed solution is based on the PassowrdChar property, which is not natively supported by RichTextBox. I do not wish to create an inherited class for a property which is not even being used as such, only to suppress displaying the user input at input time.
You can actually use the KeyDown event. By doing that, you have an ability to validate the user input.
Tutorial
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
//
// Detect the KeyEventArg's key enumerated constant.
//
if (e.KeyCode == Keys.Enter)
{
MessageBox.Show("You pressed enter! Good job!");
}
else if (e.KeyCode == Keys.Escape)
{
MessageBox.Show("You pressed escape! What's wrong?");
}
}
With that said, you have to store user input in string variable, validate it through the event and only then set variable value in textbox.
You can use this:
private void richTextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
char c = e.KeyChar;
// ..
// handle the character as needed
// ..
e.Handled = true; // suppress the RTB from receiving it
}
Note that you may or may not want to treat mouse events like right mouseclicks to control inserting via the mouse..
I'm pretty stuck here and I need help.
I got a lot of text boxes in my form, some visible and some invisible.
I want that Button2 will be active only when all text boxes (that are not hidden) are not empty (At least one character or number)
I saw all kinds of codes, but I could not figure out how to do it. (and it's not working for me)
For example here's a code that I tried, but it did not work out.
bool invalid = this.Controls.OfType<TextBox>()
.Where(t => t.Visible)
.Any(t => string.IsNullOrWhiteSpace(t.Text));
if (invalid)
button2.Enabled = false;
I would also like an explanation if it possible.
Thank you!
Well, I would use this procedure to set the button's availability (imagine there are only three textboxes):
private void SetButton()
{
button2.Enabled = (textBox1.Text != "" || textBox1.Visible == false) && (textBox2.Text != "" || textBox2.Visible == false) && (textBox3.Text != "" || textBox3.Visible == false);
}
For each textbox, it returns a true boolean if the textbox is filled or is invisible. In order to make sure it takes effect immediately, I would double click each textbox on the designer file to get the "textBox(number)_TextChanged" eventhandler, and then call the procedure that I just made. For example:
private void textBox1_TextChanged(object sender, EventArgs e)
{
SetButton();
}
Hope this helps ^_^
A recursive method that iterates over all controls on the form and looks for visible / enabled Textboxes is how I'd do it:
private void AreControlsValid(Control.ControlCollection controls)
{
foreach (Control c in controls)
{
if (c is Textbox && c.Visible)
{
if (String.IsNullOrEmpty(((Textbox)c).Text))
return false;
}
if (c.HasChildren)
AreControlsValid(c.Controls);
}
return true;
}
*Didn't test, this is an adaptation of an answer I posted in another thread: Ability to find WinForm control via the Tag property
edit: Also you'd probably want an generic event that all your textboxes subscribe to along the lines of:
textbox_TextChanged(object sender, EventArgs e)
{
button2.Enabled = AreControlsValid(this.Controls);
}
As Steve mentioned in a comment, the problem with MyForm.Controls is that it only gets direct children controls on your form, it does not get those children's children. So if you have a form, with a groupbox, with textboxes, MyForm.Controls will get you the groupbox and not the textboxes. That's why mine is recursive; it goes all the way down.
I'm trying to use this custom method for user input validation in text boxes. But I feel something missing in this approach. Now use cant move to next text box if the validation failed. Is this a good thing or bad thing to do?
private void textBox_Validating(object sender, CancelEventArgs e)
{
TextBox currenttb = (TextBox)sender;
if (currenttb.Text == "")
{
MessageBox.Show(string.Format("Empty field {0 }", currenttb.Name.Substring(3)));
e.Cancel = true ;
}
else
{
e.Cancel = false;
}
}
Adding the handler to the textboxes with a foreach loop in the form constructor:
foreach(TextBox tb in this.Controls.OfType<TextBox>().Where(x => x.CausesValidation == true))
{
tb.Validating += textBox_Validating;
}
How about using Error Provider, it will display exclamation if validation fail
I thought it would be a bad user experience if you popup too much message box. May be you should consider use labels to display error message beside each text box. In your programm, I can't even close the window by clicking the close button if I left the text box empty.
I'm writing a desktop app in win forms using C#.I use the following code to convert my textbox to numeric textboxes :
private void txtPrice_KeyPress(object sender, KeyPressEventArgs e)
{
//if (!char.IsControl(e.KeyChar)
// && !char.IsDigit(e.KeyChar)
// && e.KeyChar != '.')
// {
// e.Handled = true;
// }
if(!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar))
{
e.Handled = true;
}
}
is it ant design pattern or technique to write above code only once, and dont write it , each time for every textbox in the form?
Subclass the TextBox class, add your numeric checking to it, and use the new text box in place of the usual one.
Example
How to: Create a Numeric Text Box
Create a new component called numeric textbox that inherits TextBoxBase class.
Your code you wrote here won't work because someone can copy and paste text values.
You have to override text_change event for that.
If you want customisation, Robert's answer is the best way to go. Alternatively, in case you're not aware of it, you could use the NumericUpDown control which is built in.
create a method....for example
private void press(object sender, KeyPressEventArgs e)
{
//what ever code here,,,,,,i dont care
}
//i am assuming you are using visual studio.net
//highlight or select your text boxes or text box....
//then go to properties window ,,,,,
//after that click on the lightening icon....or events icon
//then go to your KeyPress event------- and click the drop down button
//after that Add the Method you want to be implemented by the Control.......
I have implemented validation rules on a textBox in my WinForm and it works well. However it checks the validation only when I tab out of the field. I would like it to check as soon as anything is entered in the box and everytime the content changes. Also I'd like it to check validation as soon as the WinForm opens.
I remember doing this fairly recently by setting some events and whatnot, but I can't seem to remember how.
If you're using databinding, go to the Properties of the textbox. Open (DataBindings) at the top, click on the (Advanced) property, three dots will appear (...) Click on those. The advanced data binding screen appears. For each property of the TextBox that is bound, in your case Text, you can set when the databinding, and thus the validation, should "kick in" using the combobox Data Source Update mode. If you set it to OnPropertyChanged, it will re-evaluate as you type (the default is OnValidation which only updates as you tab).
TextChanged event
in the future you can find all of the events on the MSDN library, here's the TextBox class reference:
http://msdn.microsoft.com/en-us/library/system.windows.forms.textbox(VS.80).aspx
How will your data be valid if it isn't finished? i.e. a user types a number and you try and validate it as a date?
When binding your textbox to a bindingSource go to Advanced and select validation type
"On Property Changed". This will propagate your data to your entity on each key press.
Here is the screen shot
You should be checking on KeyPress or KeyDown events and not just your TextChanged event.
Here is a C# Example direct from the MSDN documentation:
// Boolean flag used to determine when a character other than a number is entered.
private bool nonNumberEntered = false;
// Handle the KeyDown event to determine the type of character entered into the control.
private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
// Initialize the flag to false.
nonNumberEntered = false;
// Determine whether the keystroke is a number from the top of the keyboard.
if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
{
// Determine whether the keystroke is a number from the keypad.
if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
{
// Determine whether the keystroke is a backspace.
if(e.KeyCode != Keys.Back)
{
// A non-numerical keystroke was pressed.
// Set the flag to true and evaluate in KeyPress event.
nonNumberEntered = true;
}
}
}
//If shift key was pressed, it's not a number.
if (Control.ModifierKeys == Keys.Shift) {
nonNumberEntered = true;
}
}
// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
// Check for the flag being set in the KeyDown event.
if (nonNumberEntered == true)
{
// Stop the character from being entered into the control since it is non-numerical.
e.Handled = true;
}
}