HOWTO: Check for Changed Record in Grid & Prompt User to Save

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 6.0

SUMMARY

This article shows by example how to:

• How to check to see if a record has been changed when you're using a grid to edit records in a table with Table Buffering.



• How to prompt users to update a changed record before they move to a different record.

MORE INFORMATION

If you are not familiar with Data Buffering, please see Chapter 19 in the Developer's Guide. For more information on using Forms and Controls, please see Chapters 9 and 11 in the Developer's Guide.

Step-by-Step Example

1. Create a new form. Add the Customer table (located in Samples\Data in the Visual FoxPro directory) to the form's Data Environment



2. Set the BufferMode property of the form to one of the values below:
   
   

   
         1 - Pessimistic 

   -or-
   
   

   
         2 - Optimistic 

   With either of these settings, the grid, soon to be added to the form, uses table buffering while any other controls, such as text boxes or edit boxes, uses row buffering. Alternately, the BufferModeOverride property of the cursor can be set to either of these values:
   
   

   
         4 - Pessimistic Table Buffering 

   -or-
   
   

        5 - Optimistic Table Buffering 

   The BufferMode property of the form can be set as desired. The code in this article will not work if the BufferModeOverride property of the cursor is set to either type of Row Buffering. This is because with Row Buffering on the cursor in the grid, any changes to the current record will be committed when moving to the next record in the grid and the GETFLDSTATE() function will not detect the change.



3. Add two new properties to the form, and call them nRecNum and nWhatRow. Set their Value properties to 0.



4. Add a grid to the form, and set the following properties for the grid:

   
         RecordSource = Customer
         RecordSourceType = 1 - Alias 




5. Add the following code to the indicated grid events:

   
         Init event
             ThisForm.nRecNum = RECNO()
   
         BeforeRowColChange
             ThisForm.nRecNum = RECNO()
   
         AfterRowColChange
             lMov = .F.
             IF ThisForm.nWhatRow # This.ActiveRow
                  ThisForm.nWhatRow = This.ActiveRow
                  nHold= RECNO()
                  GO ThisForm.nRecNum
                  cChange = GetFldState(-1,'Customer')
                  IF AT('2', cChange)>0
                    This.Refresh
                    lMov = .T.
                    IF MessageBox("Update Record",4)= 6
                      =TableUpdate(.T.)
                    ELSE
                      =TableRevert(.T.)
                    ENDIF
                   ENDIF
                   GO nHold
                   IF lMov
                     This.Refresh
                     lMov =.F.
                   ENDIF
                 ENDIF 




6. Save and run the form.

Additional query words:

Keywords : kbcode kbVFp300 kbVFp500 kbVFp600 FxprgGrid
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