PRB: Cannot Open Form That Has =CREATEOBJECT() Property Value

ID: Q148331

3.00 3.00b WINDOWS kbtool kbprb

The information in this article applies to:

Microsoft Visual FoxPro for Windows, versions 3.0 and 3.0b

SYMPTOMS

If a form property is assigned the value =CREATEOBJECT(<classname>) with the WriteExpression() method, the form can no longer be opened in the Form Designer. If an attempt is made to open the form, the error message "Data type is invalid for this property" is displayed and the Form Designer is not opened.

CAUSE

Although WriteExpression allows storing an object reference to a form property, this is not valid in Visual FoxPro.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

1. Create a program that contains the following code:

   IF FILE('myform.scx')
     ERASE myform.scx
     ERASE myform.sct
   ENDIF
   CLEAR TYPEAHEAD
   KEYBOARD '{ALT+M}pmyprop{ENTER}'
   KEYBOARD '{ALT+F}cy'
   CREATE FORM myform
   MODIFY FORM myform NOWAIT
   =ASELOBJ(x,1)
   x(1).WRITEEXPRESSION('myprop',"=CREATEOBJECT('commandbutton')")
   CLEAR TYPEAHEAD
   KEYBOARD 'Y'
   CLOSE ALL

2. Run the program.

3. Try to open the Myform form in the Form Designer by choosing Open from

   the File menu. Select Form under Files of Type, and then select Myform.
   The message "Data type is invalid for this property" will be displayed
   and the Form Designer does not open.

NOTE: If =CREATEOBJECT(<classname>) is entered through the property sheet, the error message is displayed and the property is reset to its original value.

How to Repair the Form

If the form cannot be opened (as described in Step 3), you can repair it by using this procedure:

1. Make a backup copy of the form's .scx and .sct files:

   Copy file <formname>.scx to file <formname>.sbx
   Copy file <formname>.sct to file <formname>.sbt

2. Open the form's .scx file as a table by entering the following commands

   in the Command window:

   USE <formname>.scx
   BROWSE FIELDS properties FOR UPPER("(crea") $ UPPER(properties)

3. Double-click the word Memo. Then find and remove the following line

   where PropertyName is the name of the property assigned the
   =CREATEOBJECT() expression:

      <PropertyName>=CREATEOBJECT(<classname>)

   NOTE: Do not change any other lines. Changing any other lines may render
   the form unusable.

4. Type a USE command in the Command window to close the .scx file. You

   should now be able to open the form in the Form Designer. If the form
   opens properly, you can delete the backup files created in Step 1.

Additional reference words: 3.00 3.00b VFoxWin KBCategory: kbtool kbprb KBSubcategory: FxtoolFormdes

Keywords          : FxtoolFormdes 
Version           : 3.00 3.00b
Platform          : WINDOWS