Q133016: PRB: Dynamically Changing Buffering Mode Doesn’t Work

Article: Q133016
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0
Operating System(s): 
Keyword(s): 
Last Modified: 03-AUG-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
========

Dynamically changing the BufferModeOverride property of the Data environment
changes the property, but not the behavior of the buffering. A dialog box
reporting "Property setting will not take effect until data environment
reloaded" also appears.

CAUSE
=====

Visual FoxPro does not change the behavior of the BufferModeOverride property
dynamically while the tables are open. However, you can resolve the issue by
closing the tables with the CloseTables method. Then change the property, and
then open the tables again with the OpenTables method. The new setting of the
buffering will then take effect.

RESOLUTION
==========

The following steps show you how to create a form that contains a combo box that
allows you to change the BufferModeOverride property dynamically.

1. Create a new form. Set the DataSession property to 2 and the Caption property
  to Customer. In the ACTIVATE method of the form, enter the following code:

     THISFORM.Refresh

2. Using the right mouse button, click the form, and choose Data Environment.
  Then Using the right mouse button again, click the Data Environment window,
  and choose Add.

  Add the CUSTOMER.DBF table located in the C:\VFP\SAMPLES\DATA or equivalent
  directory. Drag the first three fields in this table (Cust_Id, Company and
  Contact) onto the form.

3. Create a combo box and set the RowSourceType property to 1. Enter the
  following value into the RowSource property: "1- Use Form Setting,2 -
  Pessimistic Row,3 - Optimistic Row,4 - Pessimistic Table,5 - Optimistic
  Table"

4. In the Valid method of the combo box, enter this code:

        THISFORM.Dataenvironment.CloseTables
        THISFORM.Dataenvironment.Cursor1.BufferModeOverride = THIS.ListIndex
        THISFORM.Dataenvironment.OpenTables

  In the Init method of the combo box, enter this code:

        THIS.ListIndex=1

5. Add a command button to the form, and enter Next in the Caption property.
  Enter the following code in the Click method:

     SKIP
     THISFORM.Refresh

6. Add another command button with Previous as the Caption with the following
  code in the Click method:

     SKIP - 1
     THISFORM.Refresh

7. Add another command button with Exit as the Caption, and enter the following
  code in the Click method:

     RELEASE THISFORM

8. Add a final command button with Write as the Caption, and enter the following
  code in the Click method:

     IF TABLEUPDATE(.T.,.F.)
        =MESSAGEBOX("SUCCESS",64)
     ELSE
        nAnswer=MESSAGEBOX("FAILURE - Write this New data ?",52)
        IF nAnswer=6
           =TABLEUPDATE(.T.,.T.)
        ELSE
           =TABLEREVERT(.T.)
           THISFORM.Refresh
        ENDIF
     ENDIF

9. Save the form, and create two instances of the form. You can now change the
  buffering dynamically with the combo box.

NOTE: Instead of changing the BufferModeOverride property, you can use the
CURSORSETPROP() function to do the same thing. This method does not require you
to open and close the tables. To use Table Buffering, ensure that MULTILOCKS is
set ON. Below is a code example using the CURSORSETPROP() function:

     =CURSORSETPROP('Buffering',THIS.ListIndex)

STATUS
======

This behavior is by design.

Additional query words: VFoxWin akz

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

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