[GRASS-user] v.to.db

[Markus Neteler]

Hi Paolo,

I have tried your script:

On Tue, Jan 20, 2009 at 1:17 PM, Paolo Craveri <pcraveri at gmail.com> wrote:
> Hi all
>
> I cannot understand why v.to.db needs a connected table  on layer 1 to
> upload   values on table linked to layer 2; e.g.:
>
> # # # spearfish60
> g.copy vect=archsites,mypoints --o
> v.category in=mypoints out=mypoints2 layer=2 opt=add --o
> # # # remove connection from layer 1
> v.db.connect -d mypoints2 layer=1
> # # # remove table from layer 1
> db.droptable mypoints2 -f
> # # # create a table
> echo "CREATE TABLE mypoints2_2 (cat integer, x double precision, y double precision)" | db.execute

(note that there is v.db.addtable)

> # # # connect table to layer 2
> v.db.connect map=mypoints2 layer=2 key=cat table=mypoints2_2
> # # # try v.to.db to upload some values to table on layer 2 without
> table on layer 1
> v.to.db mypoints2 layer=2 opt=cat  col=cat
> v.to.db mypoints2 layer=2 opt=coor col=x,y
> # # # get an error:
> # # # ERROR: Database connection not defined for layer 1. Use v.db.connect first.

Yes, I also get this and don't think that it is correct.

Looking at the code I see
http://trac.osgeo.org/grass/browser/grass/branches/develbranch_6/vector/v.to.db/main.c#L44
    Fi = Vect_get_field(&Map, options.field);

I added a local debug statement and found options.field==2 as you
defined via "layer=2".

Subsequently nothing is found since AFAIK the fields internally start
with 0, not one. I may be wrong though.

Anyone here having an idea?

The function is:
http://download.osgeo.org/grass/grass6_progman/field_8c-source.html#l00400
struct field_info *Vect_get_field(struct Map_info *Map, int field)

Markus


> # # # no error if layer 1 is connected to table
> # # # create a foo table on layer 1
> v.db.addtable mypoints2 layer=1
> # # # v.to.db upload correctly values to table on layer 2
> v.to.db mypoints2 layer=2 opt=cat  col=cat
> v.to.db mypoints2 layer=2 opt=coor col=x,y
>
> Are there any particular reasons for that?
>
> ciao
>
> --
> --
> Paolo C.
> Lat. 44° 39' 11.08'' N  Long. 7° 23' 25.26'' E
>
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