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Q136279: PRB: Program Error While Using Search in Wizard-Generated Form

Article: Q136279
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0
Operating System(s): 
Keyword(s): 
Last Modified: 15-FEB-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0 
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SYMPTOMS
========

Clicking the Find button on a Wizard-generated form and selecting an operator
(or typing a value) that is not compatible with the data type of the selected
field results in this error message:

  Function argument value, type, or count is invalid

CAUSE
=====

The Visual FoxPro Form Wizard does not implicitly call an error-handling
procedure.

RESOLUTION
==========

The developer needs to implement an error-handling routine to trap for any
errors that occur, call it in the Init event procedure of the Wizard- generated
form, and set it back to the default in the Destroy event. The procedure itself
can be contained in a .prg file that also calls the form.

Step-by-Step Example
--------------------

The following example shows how to implement a simple error-handling routine
similar to the FoxPro version 2.6 Screen Wizard.

1. Create a form by using the Form Wizard.

2. Modify the form, and in the form's Init event procedure, add this code:

     On Error Do MyErrorHandler in CallProg

3. In the form's Destroy event procedure, add "On Error" (without the quotation
  marks). Now, closing the form will reset the error routine to the one Visual
  FoxPro uses by default.

4. Exit and save the form.

5. Create the following program, and name it CallProg:

     DO FORM <formname>

     PROCEDURE MyErrorHandler
        WAIT WINDOW MESSAGE()

6. Close and save the program. Use the DO command to run it. Cause the the
  error. Now the error message is displayed in the Wait window. The user is no
  longer given options that could disable the form's functionality.

STATUS
======

This behavior is by design.

Additional query words: VFoxWin handler

======================================================================
Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbVFP300
Version           : WINDOWS:3.0

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