Geografic-Information-System/scripts/v.db.renamecolumn/v.db.renamecolumn.py

#!/usr/bin/env python

############################################################################
#
# MODULE:       v.db.renamecolumn
# AUTHOR(S):    Markus Neteler
#               Converted to Python by Glynn Clements
# PURPOSE:      interface to db.execute to drop a column from the 
#               attribute table connected to a given vector map
#               - Based on v.db.dropcolumn
#               - with special trick for SQLite and DBF (here the new col is 
#                 added/values copied/old col deleted)
# COPYRIGHT:    (C) 2007 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.
#
# TODO: MySQL untested
#############################################################################


#%module
#% description: Renames a column in the attribute table connected to a given vector map.
#% keyword: vector
#% keyword: attribute table
#% keyword: database
#%end
#%option G_OPT_V_MAP
#%end
#%option G_OPT_V_FIELD
#%end
#%option 
#% key: column
#% type: string
#% description: Old and new name of the column (old,new)
#% required: yes
#% multiple: no
#% key_desc: oldcol,newcol
#%end

import sys
import os
import grass.script as grass

def main():
    map = options['map']
    layer = options['layer']
    column = options['column']

    mapset = grass.gisenv()['MAPSET']

    if not grass.find_file(map, element = 'vector', mapset = mapset):
        grass.fatal(_("Vector map <%s> not found in current mapset") % map)

    f = grass.vector_layer_db(map, layer)

    table = f['table']
    keycol = f['key']
    database = f['database']
    driver = f['driver']

    if not table:
        grass.fatal(_("There is no table connected to the input vector map. Cannot rename any column"))

    cols = column.split(',')
    oldcol = cols[0]
    newcol = cols[1]

    if driver == "dbf":
        if len(newcol) > 10:
            grass.fatal(_("Column name <%s> too long. The DBF driver supports column names not longer than 10 characters") % newcol)

    if oldcol == keycol:
        grass.fatal(_("Cannot rename column <%s> as it is needed to keep table <%s> connected to the input vector map") % (oldcol, table))

    # describe old col
    oldcoltype = None
    for f in grass.db_describe(table)['cols']:
        if f[0] != oldcol:
            continue
        oldcoltype = f[1]
        oldcollength = f[2]

    # old col there?
    if not oldcoltype:
        grass.fatal(_("Column <%s> not found in table <%s>") % (oldcol, table))

    # some tricks
    if driver in ['sqlite', 'dbf']:
        if oldcoltype.upper() == "CHARACTER":
            colspec = "%s varchar(%s)" % (newcol, oldcollength)
        else:
            colspec = "%s %s" % (newcol, oldcoltype)

        grass.run_command('v.db.addcolumn', map = map, layer = layer, column = colspec)
        sql = "UPDATE %s SET %s=%s" % (table, newcol, oldcol)
        grass.write_command('db.execute', input = '-', database = database, driver = driver, stdin = sql)
        grass.run_command('v.db.dropcolumn', map = map, layer = layer, column = oldcol)
    elif driver == 'mysql':
        if oldcoltype.upper() == "CHARACTER":
            newcoltype = "varchar(%s)" % (oldcollength)
        else:
            newcoltype = oldcoltype

        sql = "ALTER TABLE %s CHANGE %s %s %s" % (table, oldcol, newcol, newcoltype)
        grass.write_command('db.execute', input = '-', database = database, driver = driver, stdin = sql)
    else:
        sql = "ALTER TABLE %s RENAME %s TO %s" % (table, oldcol, newcol)
        grass.write_command('db.execute', input = '-', database = database, driver = driver, stdin = sql)

    # write cmd history:
    grass.vector_history(map)

if __name__ == "__main__":
    options, flags = grass.parser()
    main()