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OLDVAL return .NULL.
Message
From
17/06/2001 16:55:21
 
 
To
17/06/2001 16:45:35
General information
Forum:
Visual FoxPro
Category:
Coding, syntax & commands
Miscellaneous
Thread ID:
00520390
Message ID:
00520404
Views:
20
>>Hi all,
>>
>>I just had a frustrating hour or more.
>>
>>A form with table buffering for specific table (of a .DBC), MULTILOCKS ON, etc...
>>
>>An APPEND BLANK, set the PK field, then SETFLDSTATE on PK field so it looks UNCHANGED.
>>In the Valid() of my subclassed TextBox I was comparing This.Value to the field's OLDVAL. Because it is a subclass the field can be anything so I deconstruct the ControlSource to construct the OLDVAL statement and I include the alias as a parameter.
>>
>>When the input field remained untouched (just tabbed through them) the compare never returned TRUE.
>>
>>I ultimately found that OLDVAL was returning .NULL. even though the field does NOT allow NULL (none of the fields in the database do).
>>
>>Is this normal? Checking OLDVAL in both VFP Help and Hacker's doesn't mention this.
>
>AFAIK SETFLDSTATE() does not work properly when used to make a row look "unchanged". HackFox3 says as much and I couldn't get it to work the way I wanted to in VFP5 either (don't know offhand if it was ever changed in VFP6).
>
>I have no idea if this is the root cause of what you're seeing.

Hi Al,

As I read Hacker's (6) the problem with SetFldState is that it cannot be used to prevent an update of the record. In my case I only use it to allow me to do a GETFLDSTATE later.
This part seems to work as I want. It was the .NULL. return that surprised me.

Thanks for the help.

JimN
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