Q140306: HOWTO: Change a Grid’s RecordSource Property Programmatically

Article: Q140306
Product(s): Microsoft FoxPro
Version(s): 
Operating System(s): 
Keyword(s): kbcode kbvfp300 kbvfp500 kbvfp600
Last Modified: 13-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 5.0, 6.0 
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SUMMARY
=======

This article shows by example how to change the RecordSource property of a grid
programmatically. It also allows you to click the column heading to change the
order of the table.

MORE INFORMATION
================

The method that does most of the work is SetGrid. It allows the user to select a
table from an Open File dialog box. It sets the RecordSource property of the
grid and the column headings to the field names in the table. It removes the any
extra columns if the tables differ in the number of the fields they contain.

The order is set in the Click event of the header. Setting the order by clicking
the column header can only be done programmatically because it requires a
subclass of the header. Columns and headers can only be subclassed in code.

When the following code is run, the user will be presented with a dialog box to
select a table. After table selection, the form appears. To change the table on
which the grid is based, the user can click the button and they will again be
presented with a dialog box to select a table.

Sample Code
-----------

     * Begin Code
     PUBLIC oGridForm
     oGridForm = CREATEOBJECT("myForm")
     oGridForm.Show

     DEFINE CLASS myForm AS FORM

         Height = 350
         ADD OBJECT myGrid AS myGrid WITH Top = 20, LEFT = 20,;
           Height = 200
         ADD OBJECT myCommand as COMMANDBUTTON WITH Top = 250,;
           Left = 20, Height = 30, Caption = "Change Grid"

         PROCEDURE myCommand.Click
             This.Parent.myGrid.SetGrid()
             GO TOP
             ThisForm.ReFresh
         ENDPROC

     ENDDEFINE

     DEFINE CLASS myGrid AS GRID

         ColumnCount = 0

         PROCEDURE Init
             This.Parent.myGrid.SetGrid()
             ThisForm.Refresh
         ENDPROC

         PROCEDURE SetGrid
             ThisForm.Lockscreen = .T.
             lcFileName = GETFILE("DBF","Select the Table:")
             USE (lcFileName)
             lcAlias = ALIAS()
             This.RecordSource = ""
             This.RecordSource = lcAlias
             SELECT (lcAlias )
             FOR i = 1 TO FCOUNT()
                 IF This.ColumnCount < i
                    This.AddObject("column" + ALLTRIM(STR(i)),"MyColumn")
                 ENDIF
                 This.Columns(i).Visible = .t.
                 This.Columns(i).ControlSource = FIELD(i)
                 This.Columns(i).Header1.Caption = FIELD(i)
             ENDFOR
             FOR i = FCOUNT() + 1 TO This.ColumnCount
                 This.RemoveObject("Column"+ALLTRIM(STR(i)))
             ENDFOR
             ThisForm.Caption = lcAlias
             ThisForm.Lockscreen = .F.
          ENDPROC

     ENDDEFINE

     DEFINE CLASS myColumn as Column

         ADD OBJECT Header1 as myHeader WITH Visible = .T.

     ENDDEFINE

     DEFINE CLASS myHeader AS HEADER

         PROCEDURE Click
            FOR nCount = 1 TO 254
                IF !EMPTY(TAG(nCount))
                   IF This.Caption = TAG(nCount)
                      SET ORDER TO This.Caption
                      EXIT
                   ENDIF
                ELSE
                   EXIT
                ENDIF
            ENDFOR
            This.Parent.Parent.ReFresh
            This.Parent.Parent.SetFocus
         ENDPROC

     ENDDEFINE
     * End Code

Additional query words:

======================================================================
Keywords          : kbcode kbvfp300 kbvfp500 kbvfp600 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP500 kbVFP600
Issue type        : kbhowto

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