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Q179298: PRB: Null RuleExpression, RuleText, and Default View Properties

Article: Q179298
Product(s): Microsoft FoxPro
Version(s): MACINTOSH:3.0b; WINDOWS:3.0,3.0b,5.0,5.0a
Operating System(s): 
Keyword(s): kbHWMAC kbvfp
Last Modified: 11-DEC-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Macintosh, version 3.0b 
- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a 
-------------------------------------------------------------------------------

SYMPTOMS
========

The following error message is returned when you attempt to use a view:

  Error reading a property from the database. The property is ignored.

CAUSE
=====

Setting the RuleExpression, RuleText, and/or the Default property of a view
field to an illegal value causes this behavior. Examples of illegal values
include the null string ("") or setting a RuleExpression property to a text
string, such as "This field cannot be empty."

RESOLUTION
==========

In order to prevent the error message from appearing it is necessary to re-
create the view with valid field properties.

The following code re-creates a view from the view definition stored in the
database container:

     PARAMETER viewname
     thisversion=VERSION()
     IF LEFT(ALLTRIM(thisversion),6)="Visual"
        thisversion=VAL(SUBSTR(thisversion,15,2))
     ELSE
        thisversion=0
     ENDIF
     SET EXCLUSIVE ON
     SET MULTILOCKS ON
     DECLARE viewprops[1,5]
     OPEN DATABASE home()+"\SAMPLES\DATA\TESTDATA" EXCL
     sql_statement=DBGETPROP(viewname,"VIEW","SQL")
     llsendupdates=DBGETPROP(viewname,'View','SendUpdates')
     lnupdatetype=DBGETPROP(viewname,'View','UpdateType')
     lnwheretype=DBGETPROP(viewname,'View','WhereType')
     lnbatchupdatecount=DBGETPROP(viewname,'View','BatchUpdateCount')
     lnusememosize=DBGETPROP(viewname,'View','UseMemoSize')
     lnfetchsize=DBGETPROP(viewname,'View','FetchSize')
     llfetchmemo=DBGETPROP(viewname,'View','FetchMemo')
     lnmaxrecords=DBGETPROP(viewname,'View','MaxRecords')
     lctables=DBGETPROP(viewname,'View','Tables')
     lccomment=DBGETPROP(viewname,'View','Comment')
     IF thisversion>=5
        llprepared=DBGETPROP(viewname,'View','Prepared')
        llcomparememo=DBGETPROP(viewname,'View','CompareMemo')
        llfetchasneeded=DBGETPROP(viewname,'View','FetchAsNeeded')
     ENDIF
     USE &viewname
     =AFIELDS(viewflds,viewname)
     USE
     FOR i=1 TO ALEN(viewflds,1)
        DIMENSION viewprops[i,5]
        fld_name=viewflds[i,1]
        viewfield=ALLTRIM(viewname)+"."+ALLTRIM(fld_name)
        viewprops[i,1]=DBGETPROP(viewfield,'Field','KeyField')
        viewprops[i,2]=DBGETPROP(viewfield,'Field','Updatable')
        viewprops[i,3]=DBGETPROP(viewfield,'Field','UpdateName')
        viewprops[i,4]=DBGETPROP(viewfield,'Field','DataType')
        viewprops[i,5]=DBGETPROP(viewfield,'Field','Caption')
     NEXT
     DELETE VIEW &viewname
     CREATE SQL VIEW &viewname AS &sql_statement
     =DBSETPROP(viewname,'View','SendUpdates',llsendupdates)
     =DBSETPROP(viewname,'View','UpdateType',lnupdatetype)
     =DBSETPROP(viewname,'View','WhereType',lnwheretype)
     =DBSETPROP(viewname,'View','BatchUpdateCount',lnbatchupdatecount)
     =DBSETPROP(viewname,'View','UseMemoSize',lnusememosize)
     =DBSETPROP(viewname,'View','FetchSize',lnfetchsize)
     =DBSETPROP(viewname,'View','FetchMemo',llfetchmemo)
     =DBSETPROP(viewname,'View','MaxRecords',lnmaxrecords)
     =DBSETPROP(viewname,'View','Tables',lctables)
     =DBSETPROP(viewname,'View','Comment',lccomment)
     IF thisversion>=5
        =DBSETPROP(viewname,'View','Prepared',llprepared)
        =DBSETPROP(viewname,'View','CompareMemo',llcomparememo)
        =DBSETPROP(viewname,'View','FetchAsNeeded',llfetchasneeded)
     ENDIF
     FOR i=1 TO ALEN(viewflds,1)
        fld_name=viewflds[i,1]
        viewfield=ALLTRIM(viewname)+"."+ALLTRIM(fld_name)
        =DBSETPROP(viewfield,'Field','KeyField',viewprops[i,1])
        =DBSETPROP(viewfield,'Field','Updatable',viewprops[i,2])
        =DBSETPROP(viewfield,'Field','UpdateName',viewprops[i,3])
        =DBSETPROP(viewfield,'Field','DataType',viewprops[i,4])
        =DBSETPROP(viewfield,'Field','Caption',viewprops[i,5])
     NEXT
     RETURN

STATUS
======

Microsoft is researching this problem and will post new information here in the
Microsoft Knowledge Base as it becomes available.

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

When a view is created, the default value for the RuleExpression, RuleText, and
Default field properties is a null string.

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

1. Create a program called Bogus.prg with the following code:

        OPEN DATABASE home()+"\SAMPLES\DATA\TESTDATA"
        CREATE SQL VIEW customerview ;
           AS SELECT DISTINCT cust_id, company, contact ;
           FROM testdata!customer ;
           ORDER BY customer.cust_id
        =DBSETPROP('CUSTOMERVIEW.Cust_id','Field','RuleExpression', ;
           'len(alltrim(cust_id))>0') && Fails with null.
        =DBSETPROP('CUSTOMERVIEW.Cust_id','Field','RuleText', ;
           "this field cannot be empty") && Fails either way.
        =DBSETPROP('CUSTOMERVIEW.Cust_id','Field','Default', ;
           "alltrim(str(reccount()+1))") && Fails with null.
        =DBSETPROP('customerview.Company','Field','RuleExpression', ;
           'company<>0') && Fails with null.
        =DBSETPROP('customerview.Company','Field','RuleText', ;
           "it cannot be empty")
        =DBSETPROP('customerview.Company','Field','Default', ;
           'reccount()+1') && Fails with null.
        USE CUSTOMERVIEW
        BROWSE

2. In the FoxPro Command window type "DO Bogus".

  When the program runs and the view is used, the following error message is
  displayed twice:

  Error reading a property from the database. The property is ignored.

Additional query words:

======================================================================
Keywords          : kbHWMAC kbvfp 
Technology        : kbHWMAC kbOSMAC kbVFPsearch kbAudDeveloper kbVFP300bMac kbVFP300 kbVFP300b kbVFP500 kbVFP500a
Version           : MACINTOSH:3.0b; WINDOWS:3.0,3.0b,5.0,5.0a
Issue type        : kbprb

=============================================================================

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