3/27/2023 0 Comments Winform errorprovider![]() ![]() If (!string.lsNullOrEmpty(m_UsernameTextBox.Text) & For example, if you want to validate the user's password when the focus leaves the password text box, you could have a handler for the Validating event that looks like private void On Password Validating (object sender, CancelEventArgs e) Typically, you will set the error provider error message in response to the Validating event discussed earlier. TheSetError method takes two arguments: a reference to the control for which you are setting the error, and the error message to set.įigure 10.3. You set an error message for a control by calling the SetError method on the error provider control instance in your form. If you set an error message for a control that isn't null or an empty string, the error provider extender control will draw an error icon next to that control and will also display a tooltip when you hover the mouse over the error icon, as shown in Figure 10.3. The error provider control maintains a mapping of error messages associated with each control on the form. When you use an error provider control, you only need to add one to your form, and it shows up in the nonvisual components tray at the bottom of the designer (see Figure 10.2).įigure 10.2. The error provider (the ErrorProvider class) control is a special kind of control, called anextender provider control, that lets you add properties to other controls on the form from a single instance of the extender provider. Windows Forms 1.0 included the ErrorProvider control that provides a standard and less obtrusive way to notify a user of an error. Although this works, it is extremely disruptive to most users to use pop-up dialogs for something like this. If you want to limit the user for number of digit, use: textBox1.In the example of handling the Validating event at the beginning of this chapter, I used the crude approach of popping up a message box when a validation error occurred. You could also add a check for '-' if your TextBox should allow negative values. You can remove the check for '.' (and the subsequent check for more than one '.') if your TextBox shouldn't allow decimal places. ![]() If (!char.IsControl(e.Ke圜har) & !char.IsDigit(e.Ke圜har) & I've had success with this two event handlers on a standard TextBox: private void textBox1_KeyPress(object sender, KeyPressEventArgs e) ![]() Handle the appropriate keyboard events to prevent anything but numeric input. Of course it also gives your users the ability to hit the up and down arrows on the keyboard to increment and decrement the current value. NumericUpDown does the filtering for you, which is nice. load the control with the appropriate data If(textbox1.text="MyName") // which will be For example: UserContrl1_LOadDataMethod() Textbox1.Invoke(new MethodInvoker(delegate )) ĭo your serious processing in the separate thread before you attempt to switch back to the control's thread. The solution you want then should look like: UserContrl1_LOadDataMethod() So only accessing the value so that corresponding data can be fetched from the database. I'm not going to do it ever from a child thread. I don't want to change the value of a control from the child thread. Situation is this: I want to load data into a global variable based on the value of a control. I guess I have not presented the question properly. Are there any more 'elegant' solutions out there?Īs per Prerak K's update comment (since deleted): I really don't see this as an ideal approach. I default everything to not CauseValidation, enables them all before I use the event for validating the whole form, and disables them all after again. So basic question is, what is the best approach to validate a specific set of controls only when I want to and not when focus is lost from the control?ĮDIT: presently as a work around, I have a method that toggles the "CausesValidation" property on and off. I have been using the ErrorProvider class to support this visually. They use "e.Cancel = true " to cancel the validation. However, I don't want to have the validation run when the textboxes lose focus, only when the whole form is being validated.Įach control that I want to be validated, I have registered with the "validating" event. I only want to close the form if the validation is successful. MessageBox.Show("Validation passed with flying colours. So I have an event that fires for that like so: if (!this.ValidateChildren()) However, I only want this validation to occur when I click a button. I have a C# winform project that I want to validate a form before closing. ![]()
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