Type-less geometry column

[Ben Harper]

Hi,
Is there any way to create an untyped geometry column? All I really
want is to be able to create a column that can accept MULTIPOLYGON as
well as POLYGON types (and likewise for LINESTRING).

From digging in the code a bit, it seems like the best solution is to
add a 'GEOMETRY' datatype that will accept any value. I've tried doign
this with AddGeometryColumn(), and I notice that it accepts type
'GEOMETRY', and this appears so far to work.

However, the docs mention nothing about this, so I'm wondering what
the thinking is here?

Thanks,
Ben

[a.furieri]

Hi Ben,

your question is a really old one:
and it's since OGC-SFS introduction
that a 'standard' answer exists:

a) a LINESTRING simply is a MULTILINESTRING
containing only one entity
b) the same is for POLYGON vs MULTIPOLYGON

so, when using any OGC-SFS DMBS, you simply have to:
- declare a MULTIxxxx column
- then representing any single-geometry using the
corresponding MULTI-format

SpatiaLite make things even easier:
you can use the appropriate type-casting
function e.g.:

CastToMultiLinestring(linestring)
CastToMultiPolygon(polygon)

this is completely harmless, so you can
safely invoke the followings as well:

CastToMultiLinestring(multilinestrin)
CastToMultiPolygon(multipolyon)

you'll get back anyway a MULTIxxxxx
in any case.

please note: this approach is exactly the
same implemented by PostGIS and by many others
OGC-SFS compliant DBMS

bye
Sandro

[Ben Harper]

Thanks a lot!
I was jumping hoops around PostGIS, ripping out the constraints etc.
I'll do as you suggest.

Regards,
Ben