Geografic-Information-System/lib/vector/Vlib/dbcolumns.c

/*!
   \file dbcolumns.c

   \brief Vector library - DB info on vectors maps

   Higher level functions for reading/writing/manipulating vectors.

   (C) 2005-2008 by the GRASS Development Team

   This program is free software under the 
   GNU General Public License (>=v2). 
   Read the file COPYING that comes with GRASS
   for details.

   \author Markus Neteler

   \date 2005-2008
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <grass/glocale.h>
#include <grass/gis.h>
#include <grass/Vect.h>
#include <grass/dbmi.h>

/*!
   \brief Fetches list of DB column names of vector map attribute table

   \param Map vector map
   \param field layer number

   \return list of column(s) names on success
   \return NULL on error 
 */
const char *Vect_get_column_names(struct Map_info *Map, int field)
{
    int num_dblinks, ncols, col;
    struct field_info *fi;
    dbDriver *driver = NULL;
    dbHandle handle;
    dbString table_name;
    dbTable *table;
    char buf[2000];


    num_dblinks = Vect_get_num_dblinks(Map);
    if (num_dblinks <= 0)
	return (NULL);

    G_debug(3,
	    "Displaying column names for database connection of layer %d:",
	    field);
    if ((fi = Vect_get_field(Map, field)) == NULL)
	return (NULL);
    driver = db_start_driver(fi->driver);
    if (driver == NULL)
	return (NULL);
    db_init_handle(&handle);
    db_set_handle(&handle, fi->database, NULL);
    if (db_open_database(driver, &handle) != DB_OK)
	return (NULL);
    db_init_string(&table_name);
    db_set_string(&table_name, fi->table);
    if (db_describe_table(driver, &table_name, &table) != DB_OK)
	return (NULL);

    ncols = db_get_table_number_of_columns(table);
    sprintf(buf, " ");
    for (col = 0; col < ncols; col++) {
	if (col == 0)
	    sprintf(buf, "%s",
		    db_get_column_name(db_get_table_column(table, col)));
	else
	    sprintf(buf, "%s,%s", buf,
		    db_get_column_name(db_get_table_column(table, col)));
    }
    G_debug(3, "%s", buf);

    db_close_database(driver);
    db_shutdown_driver(driver);

    return G_store(G_chop(buf));
}

/*!
   \brief Fetches list of DB column types of vector map attribute table

   \param Map vector map
   \param field layer number

   \return list of column(s) types on success
   \return NULL on error 
 */
const char *Vect_get_column_types(struct Map_info *Map, int field)
{
    int num_dblinks, ncols, col;
    struct field_info *fi;
    dbDriver *driver = NULL;
    dbHandle handle;
    dbString table_name;
    dbTable *table;
    char buf[2000];


    num_dblinks = Vect_get_num_dblinks(Map);
    if (num_dblinks <= 0)
	return (NULL);

    G_debug(3,
	    "Displaying column types for database connection of layer %d:",
	    field);
    if ((fi = Vect_get_field(Map, field)) == NULL)
	return (NULL);
    driver = db_start_driver(fi->driver);
    if (driver == NULL)
	return (NULL);
    db_init_handle(&handle);
    db_set_handle(&handle, fi->database, NULL);
    if (db_open_database(driver, &handle) != DB_OK)
	return (NULL);
    db_init_string(&table_name);
    db_set_string(&table_name, fi->table);
    if (db_describe_table(driver, &table_name, &table) != DB_OK)
	return (NULL);

    ncols = db_get_table_number_of_columns(table);
    sprintf(buf, " ");
    for (col = 0; col < ncols; col++) {
	if (col == 0)
	    sprintf(buf, "%s",
		    db_sqltype_name(db_get_column_sqltype
				    (db_get_table_column(table, col))));
	else
	    sprintf(buf, "%s,%s", buf,
		    db_sqltype_name(db_get_column_sqltype
				    (db_get_table_column(table, col))));
    }
    G_debug(3, "%s", buf);

    db_close_database(driver);
    db_shutdown_driver(driver);

    return G_store(G_chop(buf));
}


/*!
   \brief Fetches list of DB column names and types of vector map attribute table

   \param Map vector map
   \param field layer number

   \return list of column(s) types on success
   \retutn NULL on error 
 */
const char *Vect_get_column_names_types(struct Map_info *Map, int field)
{
    int num_dblinks, ncols, col;
    struct field_info *fi;
    dbDriver *driver = NULL;
    dbHandle handle;
    dbString table_name;
    dbTable *table;
    char buf[2000];


    num_dblinks = Vect_get_num_dblinks(Map);
    if (num_dblinks <= 0)
	return (NULL);

    G_debug(3,
	    "Displaying column types for database connection of layer %d:",
	    field);
    if ((fi = Vect_get_field(Map, field)) == NULL)
	return (NULL);
    driver = db_start_driver(fi->driver);
    if (driver == NULL)
	return (NULL);
    db_init_handle(&handle);
    db_set_handle(&handle, fi->database, NULL);
    if (db_open_database(driver, &handle) != DB_OK)
	return (NULL);
    db_init_string(&table_name);
    db_set_string(&table_name, fi->table);
    if (db_describe_table(driver, &table_name, &table) != DB_OK)
	return (NULL);

    ncols = db_get_table_number_of_columns(table);
    sprintf(buf, " ");
    for (col = 0; col < ncols; col++) {
	if (col == 0)
	    sprintf(buf, "%s(%s)",
		    db_get_column_name(db_get_table_column(table, col)),
		    db_sqltype_name(db_get_column_sqltype
				    (db_get_table_column(table, col))));
	else
	    sprintf(buf, "%s,%s(%s)", buf,
		    db_get_column_name(db_get_table_column(table, col)),
		    db_sqltype_name(db_get_column_sqltype
				    (db_get_table_column(table, col))));
    }
    G_debug(3, "%s", buf);

    db_close_database(driver);
    db_shutdown_driver(driver);

    return G_store(G_chop(buf));
}