Form validating after button click vb


15-Mar-2018 02:36

A control's intention to support validation is indicated by setting its Causes Validation property to True, the default value for all controls.

When a control's Causes Validation property is set to True, its Validating event is fired if focus shifts to another control that also has a Causes Validation value of True.

The story begins with Jerry arriving at Karen's apartment.

After a few moments of friendly banter, Karen rather unusually asks Jerry for two forms of identification—a major credit card and valid driver's license.

Alas, users may not be able to click Cancel if the control they're currently on is invalid because focus is retained since the Cancel button's Causes Validation is also set to True by default.

This situation is easily avoided by setting the Cancel button's Causes Validation property to False, thereby preventing Validating from being fired on any controls that focus shifts from, shown in Figure 4. Preventing validation With approximately 60 lines of code, our Add New Employee form supports basic validation.

Michael Weinhardt 16, 2004 Summary: Data validation is a key step in ensuring clean data capture and subsequent processing and reporting.

This installment explores the programmatic validation infrastructure native to Windows Forms and builds upon that foundation to develop a custom library of validation components designed to provide a more productive validation experience akin to using ASP. (24 printed pages) Download the winforms03162004_sample file.

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Writing more and more code in the face of increasing UI complexity is not a scalable technique and obviously best avoided.If the default of False (valid field), the Validated event is fired and focus shifts to the new control. Visually speaking, this technique has two problems: The Error Provider component turns out to be a better option as a mechanism for error notification for one or more controls, using a combination of icon and tool tip to notify the user of an error and display an appropriate message in close proximity to the related control, as shown in Figure 3. Error Provider in action Enabling this component is as simple as dragging an Error Provider component onto a form and configuring its icon, blink rate, and blink style, after which the Error Provider can be incorporated into validation code: Causes Validation, Validating, and the Error Provider provide the basic infrastructure for implementing per-control validation in a pattern that we can reuse for other controls, such as txt Date Of Birth and txt Phone Number: The combination of Validating event and Error Provider component provides a great solution that dynamically validates each control at the point of impact, that is, as users enter data.