add function to check if a table is connected with some vectors; use the new function in db.droptable

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@55046 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/python/script/db.py

@@ -160,3 +160,26 @@ def db_select(sql = None, filename = None, table = None, **args):
     try_remove(fname)
         
     return tuple(result)
+
+
+def db_table_in_vector(table):
+    """Return the name of vector connected to the table.
+       It returns False if no vectors are connected to the table.
+
+       Example
+
+       @params table name of table to query
+
+    """
+    from vector import vector_db
+    nuldev = file(os.devnull, 'w')
+    used = []
+    vects = list_strings('vect')
+    for vect in vects:
+        for f in vector_db(vect, stderr=nuldev).itervalues():
+            if not f:
+                continue
+            if f['table'] == table:
+                used.append(vect)
+                break
+    return used

scripts/db.droptable/db.droptable.py

@@ -3,7 +3,7 @@
 ############################################################################
 #
 # MODULE:       db.droptable
-# AUTHOR(S):   	Markus Neteler
+# 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
@@ -43,9 +43,9 @@
 #%end
 
 import sys
-import os
 import grass.script as grass
 
+
 def main():
     table = options['table']
     force = flags['f']
@@ -53,7 +53,7 @@ def main():
     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']
@@ -64,45 +64,35 @@ def main():
     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
+    used = grass.db.db_table_in_vector(table)
     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()
-