[Gambas-user] handling database nulls

[Jeff]

On Wed, 2009-04-15 at 16:19 +0800, Werner wrote:
> Bruce wrote:
> > This has sort of been asked before. However, the answers I have found haven't 
> > helped.
> >
> > My database has a LOT of integer fields, arranged into sets of fieldwork 
> > results.  The majority of them contain nulls, quite validly as the data for a 
> > particular set may not have been entered or even collected yet.
> >
> > My Gambas problem is creating the classes for the various plot types.  Within 
> > Gambas the data items are integers. When I try and read the existing datum 
> > point into the class (as in dp.rangeheight=$dbresult!rangeheight ) it is 
> > complaining that the value is a null not an integer, as in "wanted integer, 
> > got null instead").
> >
> > Now, coercing the value of the object data to zero is NOT valid, as in the 
> > above example, the rangeheight is null not zero, as zero means 0m above the 
> > basepoint.  Similarly, coercing it to a negative value wont work either, as 
> > that means meters below the base point.
> >
> > Is there any way to set the value of an integer variable to an "uninitalised" 
> > state?
> >
> > bruce
> >   
> A solution might be to use the Variant data type instead of Integer.
> Alternatively, you could define a class that holds a data point plus a
> flag whether the data is valid.
> 

... or a collection. 
data items accessed by a key. If no data item then it's not in the
collection. 

> Werner
> 
> 
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