DOCUMENT:Q140306  13-AUG-1999  [foxpro]
TITLE   :HOWTO: Change a Grid's RecordSource Property Programmatically
PRODUCT :Microsoft FoxPro
PROD/VER:
OPER/SYS:
KEYWORDS:kbcode kbvfp300 kbvfp500 kbvfp600

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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:

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

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