DataWindow.PreValidate Method | |
Called after any status change in this data window to allow controls and menu commands to be enabled/disabled based on the current validation status.
Namespace:
VO
Assembly:
VOGUIClasses (in VOGUIClasses.dll) Version: 2.19
Syntax Remarks Tip |
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Important! This is a callback method used by X#.
Normally, it should not be called in your application code.
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This method provides some of the functionality of the WHEN clause in classical Xbase @...SAY...GET statements. However, since the GUI approach does not enforce a rigid sequence of data entry but allows the user to move from control to control at random, the logic of enabling and disabling controls must be different.
Instead of checking a condition when focus switches into the control (this is too late, a user with a mouse is already on the new control), the system must keep checking on every significant event.
DataWindow:Prevalidate() provides some automatic handling of this type of validation (through DataWindow:RegisterConditionalControls()), but it also allows you to insert custom logic by overriding the method.
The standard action in DataWindow:Prevalidate() is to call DataWindow:EnableConditionalControls(); if problems exist, it calls DataWindow:DisableConditionalControls(). DataWindow:Prevalidate() is called after the application of the standard validation, allowing the user to replace the default handling, upon success or failure of validation.
See Also