Geografic-Information-System/scripts/db.droptable/db.droptable.py

#!/usr/bin/env python

############################################################################
#
# MODULE:       db.droptable
# AUTHOR(S):   	Markus Neteler
#               Converted to Python by Glynn Clements
# PURPOSE:      Interface to db.execute to drop an attribute table
# COPYRIGHT:    (C) 2007, 2012 by Markus Neteler and 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.
#
#############################################################################

#%module
#% description: Drops an attribute table.
#% keywords: database
#% keywords: attribute table
#%end

#%flag
#% key: f
#% description: Force removal (required for actual deletion of files)
#%end

#%option G_OPT_DB_DRIVER
#% label: Name of database driver
#% description: If not given then default driver is used
#% guisection: Connection
#%end

#%option G_OPT_DB_DATABASE
#% label: Name of database
#% description:  If not given then default database is used
#% guisection: Connection
#%end

#%option G_OPT_DB_TABLE
#% description: Name of table to drop
#% required: yes
#%end

import sys
import os
import grass.script as grass

def main():
    table = options['table']
    force = flags['f']

    if not options['driver'] or not options['database']:
        # check if DB parameters are set, and if not set them.
        grass.run_command('db.connect', flags = 'c')
    
    kv = grass.db_connection()
    if options['database']:
        database = options['database']
    else:
        database = kv['database']
    if options['driver']:
        driver = options['driver']
    else:
        driver = kv['driver']
    # schema needed for PG?
    
    if force:
	grass.message(_("Forcing ..."))
    
    # check if table exists
    nuldev = file(os.devnull, 'w')
    if not grass.db_table_exist(table):
	grass.fatal(_("Table <%s> not found in database <%s>") % \
                        (table, database))
    
    # check if table is used somewhere (connected to vector map)
    used = []
    vects = grass.list_strings('vect')
    for vect in vects:
	for f in grass.vector_db(vect, stderr = nuldev).itervalues():
	    if not f:
		continue
	    if f['table'] == table:
		used.append(vect)
		break
    if len(used) > 0:
	grass.warning(_("Deleting table <%s> which is attached to following map(s):") % table)
	for vect in used:
	    grass.warning("%s" % vect)
    
    if not force:
	grass.message(_("The table <%s> would be deleted.") % table)
	grass.message("")
	grass.message(_("You must use the force flag to actually remove it. Exiting."))
	sys.exit(0)
    
    p = grass.feed_command('db.execute', input = '-', database = database, driver = driver)
    p.stdin.write("DROP TABLE " + table)
    p.stdin.close()
    p.wait()
    if p.returncode != 0:
  	grass.fatal(_("Cannot continue (problem deleting table)."))
    
if __name__ == "__main__":
    options, flags = grass.parser()
    main()