The ErrorProvider class exposes DataSource and DataMember properties that let you tie it into a data source the same way as other bound controls on the form. You can also tie the error provider to a data source and let it extract any error information from the data source. If you want different behavior for different controls on the form, you will need to use separate instances of the error provider control with the appearance properties set statically, and then only set error messages for a specific control against the appropriate instance of the error provider. These settings can be easily changed through the BlinkStyle and BlinkRate properties. Additionally, the default behavior is for the icon to blink initially at a blink rate of 250 milliseconds to grab the user's attention.
The icon shown in Figure 10.3 is the default icon used by the control, but you can customize this by setting thteon property to an instance of a System. The error provider will display the notification icon adjacent to the text box, as shown in Figure 10.3, and will use the provided error message for the Otherwise, it is set to an appropriate error message.
#Errorprovider password
If the username has been provided, and the password checks out, then the error provider error message is set to null for the password text box control. This method could go out to a database or look up the user in some other credential store. If the username has been provided, it calls a helper method to check the user's password. If so, it doesn't have enough information to make a decision about the password.
#Errorprovider code
The first thing the code does is to see if the username text box is empty. This handler will be invoked by default when the focus shifts from the password text box to some other control on the form. M_ErrorProvider.SetError(m_PasswordTextBox, null) M_ErrorProvider.SetError(m_PasswordTextBox, "Password is incorrect") } 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.
#Errorprovider windows
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.
Drawing.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. Font( "Microsoft Sans Serif ", 12 F, System.
/ the contents of this method with the code editor. / Required method for Designer support - do not modify # region Windows Form Designer generated code Protected override void Dispose( bool disposing) / true if managed resources should be disposed otherwise, false.
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