I think this is a generic question that's faced by most XML-based data exchange
languages (WDDX, XML-RPC, SOAP, etc) but I'm using YODEL.
The problem is that we have fields in the datasource which allow nulls in typed
cells (most DBs do this: a column can be "number" or "Boolean" but still allow
nulls).
How should a data exchange language deal with this? With a typed cell but no
value? For example
In WDDX you might see: <number></number>
In YODEL you might see: <d type="number"></d>
In XML-RPC you might see: <value><i4></i4></value>
and so on.
I can see several potential solutions:
1) Throw an error. You said I was going to get a number, but I don't see one.
This is easiest, but seems likely to cause problems when some values are
unknown (likely with some data sources).
2) Allow nulls - set anything empty like that to null (or the platform
equivalent). This I think would work... but would be very odd in practice -
the consuming platform would then have to check constantly to see if a presumed
"number" value was a number.
3) Default the value ("new number") to what the platform supports as a
"uninitialized" value (for number, say a zero, for a date perhaps now(), for a
boolean "false" and so forth). This seems to make the most sense to me on some
levels... but is also the most likely to create bad data (converting a null in
a database boolean column to "false" changes the data - and that can't ever be
good, can it?)
What doi you guys think? What do other implementations do (I'm having trouble
finding documentation on this).
Thanks,
Jim Davis
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|
Discover CFTicket - The leading ColdFusion Help Desk and Trouble
Ticket application
http://www.houseoffusion.com/banners/view.cfm?bannerid=48
Message: http://www.houseoffusion.com/lists.cfm/link=i:4:227096
Archives: http://www.houseoffusion.com/cf_lists/threads.cfm/4
Subscription: http://www.houseoffusion.com/lists.cfm/link=s:4
Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4
Donations & Support: http://www.houseoffusion.com/tiny.cfm/54
