how to get Point * from datum =heap_getattr(....)?

Started by sunpengalmost 16 years ago2 messagesgeneral
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#1sunpeng
bluevaley@gmail.com

hi,i have this table:
CREATE TABLE pois(
uid integer not null,
name VARCHAR(128),
catcode VARCHAR(32) not null,
catname VARCHAR(32),
others VARCHAR(32)
);
SELECT AddGeometryColumn('pois', 'location', 4214, 'POINT', 2);

and then in my codes,i use this invoke to get location column in tuple:
tuple = heap_getnext(pHeapScanDesc,
ForwardScanDirection);
datum = heap_getattr(tuple,6,pRawRelation->rd_att,&isnull);

then on the next,how to write to get Point? is this right?
Point *p = isnull?NULL:(Point *)(PG_DETOAST_DATUM(datum));
i've tried it,but it seems not work.

thanks a lot.

peng

#2Tom Lane
tgl@sss.pgh.pa.us
In reply to: sunpeng (#1)
Re: how to get Point * from datum =heap_getattr(....)?

sunpeng <bluevaley@gmail.com> writes:

hi,i have this table:
CREATE TABLE pois(
uid integer not null,
name VARCHAR(128),
catcode VARCHAR(32) not null,
catname VARCHAR(32),
others VARCHAR(32)
);
SELECT AddGeometryColumn('pois', 'location', 4214, 'POINT', 2);

and then in my codes,i use this invoke to get location column in tuple:
tuple = heap_getnext(pHeapScanDesc,
ForwardScanDirection);
datum = heap_getattr(tuple,6,pRawRelation->rd_att,&isnull);

then on the next,how to write to get Point? is this right?
Point *p = isnull?NULL:(Point *)(PG_DETOAST_DATUM(datum));

I'm not sure what the C-code type name is for geometry columns, but it's
definitely not Point --- that corresponds to the SQL type "point".

I'd suggest asking about this on the postgis mailing list.

regards, tom lane