[mapguide-internals] Exception thrown on null values?

[Traian Stanev]

So it will penalize everybody, instead of fixing the provider in question to throw an exception when it should?

Traian

> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-
> internals-bounces at lists.osgeo.org] On Behalf Of Bruce Dechant
> Sent: Thursday, February 28, 2008 5:12 PM
> To: MapGuide Internals Mail List
> Subject: RE: [mapguide-internals] Exception thrown on null values?
>
> Yup, but like I said at the cost of stability. :)
>
> I would rather do the check then have the server crash.
>
> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-
> internals-bounces at lists.osgeo.org] On Behalf Of Traian Stanev
> Sent: Thursday, February 28, 2008 3:09 PM
> To: MapGuide Internals Mail List
> Subject: RE: [mapguide-internals] Exception thrown on null values?
>
>
> Hmm... always doing an IsNull() for everything has an overhead as well
> -- internally to the provider it may be equivalent to getting the
> property twice. Once to check for null and another time to get the
> property value.
>
> Traian
>
>
>
> > -----Original Message-----
> > From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-
> > internals-bounces at lists.osgeo.org] On Behalf Of Bruce Dechant
> > Sent: Thursday, February 28, 2008 5:05 PM
> > To: MapGuide Internals Mail List
> > Subject: RE: [mapguide-internals] Exception thrown on null values?
> >
> > Jason,
> >
> > This is the expected behavior as Traian pointed out. This was changed
> > from what it was before because now we do the IsNull() check
> internally
> > in the server on all GetXXX() APIs just in case the user "forgot" to
> > call it. This was also done to prevent memory access violations when
> > trying to call for example GetString() from a reader that has a NULL
> > property value and the underlying provider tries to do the read
> string
> > and then crashes, by adding this check we have added some server
> > stability.
> >
> > Not all providers are created equally. :)
> >
> > Thanks,
> > Bruce
> >
> >
> > -----Original Message-----
> > From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-
> > internals-bounces at lists.osgeo.org] On Behalf Of Jason Birch
> > Sent: Thursday, February 28, 2008 2:48 PM
> > To: MapGuide Internals Mail List
> > Subject: RE: [mapguide-internals] Exception thrown on null values?
> >
> > Am I allowed to say "lame"?  :)  NULL is a perfectly valid value for
> > most data types, and throwing an exception in this case adds a lot of
> > additional processing that should not be required.
> >
> > I personally feel that this is a case where MapGuide could make
> > application developers lives a lot easier and improve (slightly?) the
> > performance of web-level apps by swallowing the exception and
> returning
> > NULL.
> >
> > Jason
> >
> > -----Original Message-----
> > From: mapguide-internals-bounces at lists.osgeo.org
> > [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of
> Traian
> > Stanev
> > Sent: Thursday, February 28, 2008 13:31
> > To: 'MapGuide Internals Mail List'
> > Subject: RE: [mapguide-internals] Exception thrown on null values?
> >
> > I think this complies with the FDO spec, which requires an exception
> to
> > be thrown when the value is null and you try to get it anyway. The
> two
> > solutions are to check for IsNull() before getting it, or to catch
> the
> > exception. The code *could* in theory return NULL in this case,
> but...
> >
> > Traian
> >
> > > -----Original Message-----
> > > From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-
> > > internals-bounces at lists.osgeo.org] On Behalf Of Jason Birch
> > > Sent: Thursday, February 28, 2008 4:29 PM
> > > To: MapGuide Internals Mail List
> > > Subject: [mapguide-internals] Exception thrown on null values?
> > >
> > > Hi,
> > >
> > > I'm seeing a case in MGOS 2.0 where MgFeatureReader->GetString() is
> > > throwing an exception when the value of the string is null.
> > >
> > > Is this expected behaviour?  Has it changed since 1.2?  I believe
> > that
> > > I've seen a similar error in geometry, but don't have a test case
> for
> > > that yet.
> > >
> > > This is relatively easy to work around with a try/catch and
> > suppressing
> > > the error output if the message includes "null", but it's a bit
> > > annoying.  Is there a better way of dealing with this?
> > >
> > > Jason
> > > _______________________________________________
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