PRB: OLE Error with Empty or NULL ControlSource with Date and Time Picker (253588)


The information in this article applies to:

  • Microsoft Visual FoxPro for Windows 6.0
This article was previously published under Q253588

SYMPTOMS

When a Date and Time Picker ActiveX control is added to a form, its ControlSource set to a date field, and the record pointer moved to a record that contains a blank value in the date field, the following error message appears:
OLE IDispatch exception code 0 from DTPicker: A date was specified that does not fall within the MinDate and MaxDate Properties...
When the record pointer is moved to a record that contains a NULL value in the date field, the following error message appears:
OLE IDispatch exception code 0 from DTPicker: Invalid Property Value.

CAUSE

The DateTimePicker control's Calendar interface handles adjusting the Day, Month, and Year properties to create a valid date. If a value is assigned that creates an invalid date, one of the error messages above appears. This behavior occurs because the DateTimePicker control does not recognize {" / / "} as a valid date. Likewise, the DateTimePicker control does not recognize a NULL as a valid date.

RESOLUTION

Use the EMPTY() or ISNULL() functions to determine whether the date field that is the ControlSource for the DateTimePicker control is blank or NULL. If the field contains a blank or NULL value, set the ControlSource property of the DateTimePicker control to a NULL string. If the field is not blank, set the ControlSource of the DateTimePicker control to the datefield. 
IF !EMPTY(TESTDTP.DTP_DATEA)
    THISFORM.DTPicker1.CONTROLSOURCE="TESTDTP.DTP_Datea"
 ELSE
     THISFORM.DTPicker1.CONTROLSOURCE=""
 ENDIF
 IF !ISNULL(TESTDTP.DTP_DATEB)
    THISFORM.DTPicker2.CONTROLSOURCE="TESTDTP.DTP_Dateb"
 ELSE
    THISFORM.DTPicker2.CONTROLSOURCE=""
ENDIF

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

  1. Create a program file named DTP_DEMO using the following code:
    PUBLIC OX
OX=CREATEOBJECT('MYFORM')
OX.SHOW
READ EVENTS

DEFINE CLASS myform AS FORM
   CAPTION = "DateTimePicker Form"
   HEIGHT = 125
   LEFT = 0
   TOP = 0
   WIDTH = 230
   NAME = "myform"

   ADD OBJECT DTPicker1 AS OLECONTROL WITH ;
      OLECLASS="MSComCtl2.DTPicker.2",;
      TOP = 5, ;
      LEFT = 5, ;
      HEIGHT = 25, ;
      WIDTH = 100, ;
      NAME = "DTPicker1"

   ADD OBJECT DTPicker2 AS OLECONTROL WITH ;
      OLECLASS="MSComCtl2.DTPicker.2",;
      TOP = 35, ;
      LEFT = 5, ;
      HEIGHT = 25, ;
      WIDTH = 100, ;
      NAME = "DTPicker2"

   ADD OBJECT commandbutton1 AS COMMANDBUTTON WITH ;
      TOP=75, ;
      LEFT=125, ;
      HEIGHT=25, ;
      CAPTION="\<Close"
   NAME="commandbutton1"

   PROCEDURE INIT
*!*      IF !EMPTY(TESTDTP.DTP_DATEA)
         THISFORM.DTPicker1.CONTROLSOURCE="TESTDTP.DTP_Datea"
*!*      ELSE
*!*         THISFORM.DTPicker1.CONTROLSOURCE=""
*!*      ENDIF
*!*      IF !ISNULL(TESTDTP.DTP_DATEB)
         THISFORM.DTPicker2.CONTROLSOURCE="TESTDTP.DTP_Dateb"
*!*      ELSE
*!*         THISFORM.DTPicker2.CONTROLSOURCE=""
*!*      ENDIF
         
   ENDPROC

   PROCEDURE commandbutton1.CLICK
      RELEASE THISFORM
   ENDPROC

   PROCEDURE LOAD
      IF !FILE('TESTDTP.DBF')
         CREATE TABLE TESTDTP (DTP_DATEA D, DTP_DATEB D NULL)
         INSERT INTO TESTDTP VALUES (CTOD('  /  /  '),(.NULL.))
      ENDIF
      IF !USED("TESTDTP")
         USE TESTDTP IN 0
      ENDIF
      SELECT TESTDTP
   ENDPROC

   PROCEDURE UNLOAD
      USE IN TESTDTP
      ERASE TESTDTP.DBF
      CLEAR EVENTS
   ENDPROC

ENDDEFINE
  2. Save and run DTP_DEMO. Note the error message that appears when the DTPicker.ControlSource is set to a date field that contains an empty value.
  3. Note the error message that appears when the DTPicker.ControlSource is set to a date field that contains a NULL value.
  4. Uncomment the commented lines of code in the Init method.

    NOTE: This example uses the Init method. If you populate the ControlSource by moving through the records of a table, you need to check for empty and NULL fields in another event.
  5. Save and run DTP_DEMO. Note that the error message does not appear.
(c) Microsoft Corporation 2000, All Rights Reserved. Contributions by John Desch, Microsoft Corporation.

REFERENCES

For additional information DTPicker ActiveX Control, click the article number below to view the article in the Microsoft Knowledge Base:

189991 PRB: Error Setting DateTimePicker's Month Programmatically

Modification Type:MajorLast Reviewed:8/27/2002
Keywords:kbContainer kbCtrl kbDSupport kbprb KB253588
©2002 Microsoft Corporation. All rights reserved.