PRB: Dynamically Changing Buffering Mode Doesn't Work (133016)

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)