PRB: Null RuleExpression, RuleText, and Default View Properties

• 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.
   

Keywords          : FxprgSql FxprgTable VFoxMac vfoxwin
Version           : MACINTOSH:3.0b; WINDOWS:3.0,3.0b,5.0,5.0a
Platform          : MACINTOSH WINDOWS
Issue type        : kbprb