[postgis-users] FW: [Psycopg] RELEASE: GeoTypes-0.2.0a1
dblasby at refractions.net
Wed Sep 24 17:43:13 PDT 2003
>>2) All the OpenGIS types (there are seven of them) have the same type oid.
>>They are implemented as subclasses of the same (GEOMETRY) base class. To deal
>>with this I have registered a factory class against the type oid and the
>>factory class works out, from the string returned by the database, which
>>subclass to create. This looked like a reasonable design to me, does anyone
>>have any other suggestions?
Yes - this is probably the best thing to do. The OGC function
GetGeometryType() basically tells you what type the actual geometry is.
So, a MULTIPOLYGON returns "MULTIPOLYGON".
Also, I suggest you plan for using WKB instead of WKT because its much
more efficient (space wise), easier to parse, and you dont lose any
precision in your coordinates.
>>3) Because the Geometry type is added to postgres on a database by database
>>basis its type oid is different for each database. I dynamically work out
>>what the type oid is by creating a table with a Geometry field and querying
>>the oid of that field. I have a feeling that I should be able to get the type
>>oid without creating the table. Does anyone know how to do this?
SELECT oid from pg_type where typname = ''geometry'' ;
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