[fdo-users] RE: Object and Association Support

Crispin_at_1Spatial crispin.hoult at 1spatial.com
Fri Jul 23 03:15:59 EDT 2010

Thanks Brent - very helpful.

So what are the architectural / compelling differences between the two?

At first glance it appears that Associations have flexible cardinality (1:1
or 1:n - or 1:n depending on the rules?) and options for cascade delete and
objects are simply a more complex attribute

Is it true that object properties are therefore forced at 1:1?  If so, I
assume the a FeatureReader for the object will just return one 'row'.  Can
this be nullable... I need to look at some practical examples, though I had
hoped to be able to do this independent of a RDBMS - ie with SQLite (but not
supported (yet!)).

The following fragment lost me:
Is the statement true for all cases or only when the "ReverseMultiplicity"
is set to TRUE?
It looks as though (through exposed by the FDOToolbox Schema Editor) an
ObjectProperty cannot be set to null - so this is implied , where the
identity property does not exist then the FeatureReader will have nothing in

Brent Robinson wrote:
> For datastores without this MetaData, an association property is generated
> for each foreign key present; but no object properties are generated

Thanks for the response - I hope this gains more popularity through
understanding (and the current issue of limited support by FDO clients).


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