DOCUMENT:Q132331  15-FEB-2000  [foxpro]
TITLE   :PRB: Null Values Disappear When Selected in a Grid or Browse
PRODUCT :Microsoft FoxPro
PROD/VER:WINDOWS:3.0
OPER/SYS:
KEYWORDS:

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The information in this article applies to:

 - Microsoft Visual FoxPro for Windows, version 3.0 
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SYMPTOMS
========

The text string ".NULL." for null values disappears when the field is selected.
When you move out of the field, ".NULL." reappears. This is by design.


RESOLUTION
==========

To display a text string ".NULL." for the currently selected field, create a
column class that displays a label with the text string ".NULL." via the
column's DynamicCurrentControl property. Copy the following code into
TESTNULL.PRG, and then run it. You will see a grid with one column and 10 rows.
Some of the rows contain numeric values, and some contain ".NULL." as a text
string. Press DOWN ARROW to move through the records, note that the text string
value of ".NULL." is displayed when the pointer is on a record that contains a
null value.

     PUBLIC oForm
     oForm = CREATEOBJECT('myform')
     oForm.SHOW

     DEFINE CLASS mytextbox AS textbox
        SpecialEffect = 1
        BorderStyle = 0
        FontBold = .F.

        PROCEDURE keypress
        LPARAMETERS nKeyCode, nShiftAltCtrl

          IF nKeyCode = 48
            REPLACE testnull.name WITH .NULL.
            This.Value = ".NULL."
            NODEFAULT
          ENDIF
        ENDPROC
     ENDDEFINE

     DEFINE CLASS mytextbox1 AS mytextbox
        ControlSource = "testnull.name"
     ENDDEFINE

     DEFINE CLASS mytextbox2 AS mytextbox
        ControlSource = "This.Value"
        Value = ".NULL."

        PROCEDURE gotfocus
           This.Value = ".NULL."
        ENDPROC

        PROCEDURE lostfocus
           IF This.Value <> ".NULL."
              REPLACE testnull.name WITH This.Value
           ENDIF
        ENDPROC
     ENDDEFINE

     DEFINE CLASS mycolumn AS column
        DynamicCurrentControl = "IIF(ISNULL(testnull.name),'text2', 'text1')"
        Sparse = .f.
        Bound = .f.

        ADD OBJECT text1 AS mytextbox1
        ADD OBJECT text2 AS mytextbox2
     ENDDEFINE

     DEFINE CLASS mygrid AS grid
        RecordSource = ALIAS()
        ADD OBJECT c1 AS mycolumn
     ENDDEFINE

     DEFINE CLASS myform AS form
        ADD OBJECT g1 AS mygrid

        PROCEDURE load
           DELETE FILE testnull.dbf
           CREATE TABLE testnull (name c(10) NULL)

           FOR cnt = 1 to 10
             APPEND BLANK
             REPLACE name WITH IIF(MOD(RAND()*100, 2) >=1, SYS(3), .NULL.)
           ENDFOR
           GO TOP
        ENDPROC

        PROCEDURE unload
           CLOSE DATA ALL
        ENDPROC
     ENDDEFINE

STATUS
======

This behavior is by design.

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

Steps to Reproduce Behavior
---------------------------

To see the behavior described above, run the following code in the Command
window:

      CREATE TABLE test (name C(10) NULL)
      APPEND BLANK
      REPLACE name WITH "Harry"
      APPEND BLANK
      REPLACE name WITH .NULL.
      BROWSE

The currently selected field has no text in it. Press the UP ARROW key or click
in record 1. Record 2 now displays the ".NULL." text string.

Additional query words: VFoxWin browse

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

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