Dear all, continuing in my C program test to access grass data without
launching a grass session and a great thanks to Glynn Clements who help me with
the first step, I begin to write few c lines to access a vector map into a
mapset (in this example the GU0507 vector in the Roujan Location and the simon9
Mapset). And it works ! Except the fact I can't access to it atttribute layer
(I use the default driver dbf)...
I try to use the db_set_handle(&handle,Fi->database,NULL) command but the
returns is a null value. Is it normal ?
After that , using db_open_database(driver,&handle) command launch a
segmentation fault. Is it because my handle is a null value ?
Are some commands missing to access or start dbf driver in my script ?
Thanks in advance for any help for a newbie in grass scripting !!
Here my script :
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
extern "C" {
#include <grass/config.h>
#include <grass/gis.h>
#include <grass/Vect.h>
#include <grass/glocale.h>
#include <grass/dbmi.h>
}
int main(int argc, char *argv[])
{
char name[GNAME_MAX];
char * gisdbase, * location,* mapset, * database;
const char * drivername, * databasename;
struct field_info *Fi;
struct Map_info In;
dbString table_name,dbsql,valstr;
dbHandle handle;
dbDriver *driver;
setenv("GISBASE","/usr/lib/grass64/dist.i486-pc-linux-gnu",1);
setenv("GISRC","/home/rabotin/prov/config",1);
setenv("PATH","$GISBASE/bin:$GISBASE/scripts:$PATH",1);
setenv("DBF_DRIVER","dbf",1);
setenv("DB_DATABASE","$GISDBASE/$LOCATION_NAME/$MAPSET/dbf",1);
if ( getenv ("GISRC") ) {
// Store default values
gisdbase = G_gisdbase();
location = G_location();
mapset = G_mapset();
drivername=db_get_default_driver_name();
databasename=db_get_default_database_name();
}
G_gisinit(argv[0]);
std::cout << gisdbase << std::endl; // return /home/rabotin/grassdata
std::cout << location << std::endl; //return Roujan
std::cout << mapset << std::endl; // return simon9
std::cout << drivername << std::endl; //return dbf
std::cout << databasename << std::endl; //return
$GISDBASE/$LOCATION_NAME/$MAPSET/dbf
strcpy(name,"GU0507");
std::cout << G_find_vector(name, G_mapset()) << std::endl; //return
simon9
Vect_open_old(&In,name, G_mapset());
std::cout << Vect_get_name(&In) << std::endl; //return GU0507
Fi=Vect_get_field(&In,1);
std::cout << &Fi << std::endl; //return 0xbfd2a294
printf("Field %d;Name %s, Driver %s, database %s, table %s, key %s
\n",Fi->number,Fi->name, Fi->driver,Fi->database,Fi->table,Fi->key);
// return Field 1;Name (null), Driver dbf, database /home/rabotin/grassdata/Roujan/simon9/dbf/, table GU0507, key cat
db_init_string(&dbsql);
db_init_string(&valstr);
db_init_string(&table_name);
db_init_handle(&handle);
driver=db_start_driver(Fi->driver);
std::cout << &driver << std::endl; //return 0xbfd2a290
std::cout <<db_set_handle(&handle,Fi->database,NULL)<< std::endl; //
return 0
// the following lines return segmentation fault
if (db_open_database(driver,&handle)!=DB_OK){
printf("pb");
}
}
My /home/rabotin/prov/config file is
GISDBASE: /home/rabotin/grassdata
LOCATION_NAME: Roujan
MAPSET: simon9
MONITOR: x0
GRASS_GUI: wxpython
--
*********************************
Michaël Rabotin
Ingénieur d'étude en géomatique
Laboratoire d'étude des Interactions Sol, Agrosystème et Hydrosystème
UMR LISAH SupAgro-INRA-IRD
Bat. 24
2 place Viala
34060 Montpellier cedex 1
FRANCE
Téléphone : 33 (0)4 99 61 23 85
Secrétariat : 33 (0)4 99 61 22 61
Fax : 33 (0)4 67 63 26 14
E-mail : [email protected]
*********************************
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