Geografic-Information-System/db/drivers/ogr/describe.c

/*****************************************************************************
*
* MODULE:       OGR driver 
*   	    	
* AUTHOR(S):    Radim Blazek
*
* PURPOSE:      DB driver for OGR sources     
*
* COPYRIGHT:    (C) 2004 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.
*
*****************************************************************************/
#include <grass/dbmi.h>
#include <grass/datetime.h>
#include <grass/gis.h>
#include "ogr_api.h"
#include "globals.h"
#include "proto.h"
#include <grass/glocale.h>

int db__driver_describe_table(dbString * table_name, dbTable ** table)
{
    int i, nlayers;
    OGRLayerH hLayer = NULL;
    OGRFeatureDefnH hFeatureDefn;

    /* Find data source */
    nlayers = OGR_DS_GetLayerCount(hDs);

    for (i = 0; i < nlayers; i++) {
	hLayer = OGR_DS_GetLayer(hDs, i);
	hFeatureDefn = OGR_L_GetLayerDefn(hLayer);
	if (G_strcasecmp
	    ((char *)OGR_FD_GetName(hFeatureDefn),
	     db_get_string(table_name)) == 0) {
	    break;
	}
	hLayer = NULL;
    }

    if (hLayer == NULL) {
	append_error("Table '%s' does not exist\n",
		     db_get_string(table_name));
	report_error();
	return DB_FAILED;
    }

    G_debug(3, "->>");
    if (describe_table(hLayer, table, NULL) == DB_FAILED) {
	append_error("Cannot describe table\n");
	report_error();
	return DB_FAILED;
    }

    return DB_OK;
}

/* describe table, if c is not NULL cur->cols and cur->ncols is also set 
 * cursor may be null
 */
int describe_table(OGRLayerH hLayer, dbTable ** table, cursor * c)
{
    int i, ncols, kcols;
    dbColumn *column;
    OGRFeatureDefnH hFeatureDefn;
    OGRFieldDefnH hFieldDefn;
    const char *fieldName;
    int ogrType;
    int *cols;

    G_debug(3, "describe_table()");

    hFeatureDefn = OGR_L_GetLayerDefn(hLayer);
    ncols = OGR_FD_GetFieldCount(hFeatureDefn);

    G_debug(3, "ncols = %d", ncols);

    /* Identify known columns */
    cols = (int *)G_malloc(ncols * sizeof(int));
    kcols = 0;
    for (i = 0; i < ncols; i++) {
	hFieldDefn = OGR_FD_GetFieldDefn(hFeatureDefn, i);
	ogrType = OGR_Fld_GetType(hFieldDefn);
	OGR_Fld_GetNameRef(hFieldDefn);
	fieldName = OGR_Fld_GetNameRef(hFieldDefn);

	if (ogrType != OFTInteger && ogrType != OFTReal &&
	    ogrType != OFTString) {
	    G_warning(_("OGR driver: column '%s', OGR type %d  is not supported"),
		      fieldName, ogrType);
	    cols[i] = 0;
	}
	else {
	    cols[i] = 1;
	    kcols++;
	}
    }

    if (!(*table = db_alloc_table(kcols))) {
	return DB_FAILED;
    }

    /* set the table name */
    /* TODO */
    db_set_table_name(*table, "");

    /* set the table description */
    db_set_table_description(*table, "");

    /* TODO */
    /*
       db_set_table_delete_priv_granted (*table);
       db_set_table_insert_priv_granted (*table);
       db_set_table_delete_priv_not_granted (*table);
       db_set_table_insert_priv_not_granted (*table);
     */

    for (i = 0; i < ncols; i++) {
	int sqlType;
	int size, precision, scale;

	if (!(cols[i]))
	    continue;		/* unknown type */

	hFieldDefn = OGR_FD_GetFieldDefn(hFeatureDefn, i);
	ogrType = OGR_Fld_GetType(hFieldDefn);
	fieldName = OGR_Fld_GetNameRef(hFieldDefn);

	G_debug(3, "field %d : ogrType = %d, name = %s", i, ogrType,
		fieldName);

	switch (ogrType) {
	case OFTInteger:
	    sqlType = DB_SQL_TYPE_INTEGER;
	    size = OGR_Fld_GetWidth(hFieldDefn);	/* OK ? */
	    precision = 0;
	    break;

	case OFTReal:
	    sqlType = DB_SQL_TYPE_DOUBLE_PRECISION;
	    size = OGR_Fld_GetWidth(hFieldDefn);	/* OK ? */
	    precision = OGR_Fld_GetPrecision(hFieldDefn);
	    break;

	case OFTString:
	    sqlType = DB_SQL_TYPE_CHARACTER;
	    size = OGR_Fld_GetWidth(hFieldDefn);
	    if (size == 0) {
		G_warning(_("column '%s', type 'string': unknown width -> stored as varchar(250) "
			   "some data may be lost"), fieldName);
		size = 250;
	    }
	    precision = 0;
	    break;

	default:
	    G_warning(_("Unknown type"));
	    break;
	}

	column = db_get_table_column(*table, i);

	db_set_column_host_type(column, ogrType);
	db_set_column_sqltype(column, sqlType);
	db_set_column_name(column, fieldName);
	db_set_column_length(column, size);
	db_set_column_precision(column, precision);

	/* TODO */
	scale = 0;
	/*
	   db_set_column_scale (column, scale);
	 */

	/* TODO */
	db_set_column_null_allowed(column);
	db_set_column_has_undefined_default_value(column);
	db_unset_column_use_default_value(column);

	/* TODO */
	/*
	   db_set_column_select_priv_granted (column);
	   db_set_column_update_priv_granted (column);
	   db_set_column_update_priv_not_granted (column); 
	 */
    }

    if (c) {
	c->cols = cols;
	c->ncols = ncols;
    }
    else {
	G_free(cols);
    }

    return DB_OK;
}