Data commit

Task/Simple-database/Python/simple-database.py

@@ -0,0 +1,108 @@
+#!/usr/bin/python3
+
+'''\
+Simple database for: http://rosettacode.org/wiki/Simple_database
+
+'''
+
+import argparse
+from argparse import Namespace
+import datetime
+import shlex
+
+
+def parse_args():
+    'Set up, parse, and return arguments'
+
+    parser = argparse.ArgumentParser(epilog=globals()['__doc__'])
+
+    parser.add_argument('command', choices='add pl plc pa'.split(),
+                        help='''\
+add: Add a new entry
+pl:  Print the latest entry
+plc: Print the latest entry for each category/tag
+pa:  Print all entries sorted by a date''')
+    parser.add_argument('-d', '--description',
+                        help='A description of the item. (e.g., title, name)')
+    parser.add_argument('-t', '--tag',
+                        help=('''A category or tag (genre, topic, relationship '''
+                              '''such as “friend” or “family”)'''))
+    parser.add_argument('-f', '--field', nargs=2, action='append',
+                        help='Other optional fields with value (can be repeated)')
+
+    return parser
+
+def do_add(args, dbname):
+    'Add a new entry'
+    if args.description is None:
+        args.description = ''
+    if args.tag is None:
+        args.tag = ''
+    del args.command
+    print('Writing record to %s' % dbname)
+    with open(dbname, 'a') as db:
+        db.write('%r\n' % args)
+
+def do_pl(args, dbname):
+    'Print the latest entry'
+    print('Getting last record from %s' % dbname)
+    with open(dbname, 'r') as db:
+        for line in db: pass
+    record = eval(line)
+    del record._date
+    print(str(record))
+
+def do_plc(args, dbname):
+    'Print the latest entry for each category/tag'
+    print('Getting latest record for each tag from %s' % dbname)
+    with open(dbname, 'r') as db:
+        records = [eval(line) for line in db]
+    tags = set(record.tag for record in records)
+    records.reverse()
+    for record in records:
+        if record.tag in tags:
+            del record._date
+            print(str(record))
+            tags.discard(record.tag)
+            if not tags: break
+
+def do_pa(args, dbname):
+    'Print all entries sorted by a date'
+    print('Getting all records by date from %s' % dbname)
+    with open(dbname, 'r') as db:
+        records = [eval(line) for line in db]
+    for record in records:
+        del record._date
+        print(str(record))
+
+def test():
+    import time
+    parser = parse_args()
+    for cmdline in [
+                    """-d Book -f title 'Windy places' -f type hardback --tag DISCOUNT add""",
+                    """-d Book -f title 'RC spammers'  -f type paperback -t   DISCOUNT add""",
+                    """-d Book -f title 'Splat it' -f type hardback -f special 'first edition' -t PREMIUM add""",
+                    """pl""",
+                    """plc""",
+                    ]:
+        args = parser.parse_args(shlex.split(cmdline))
+        now = datetime.datetime.utcnow()
+        args._date = now.isoformat()
+        do_command[args.command](args, dbname)
+        time.sleep(0.5)
+
+
+
+do_command = dict(add=do_add, pl=do_pl, plc=do_plc, pa=do_pa)
+dbname = '_simple_db_db.py'
+
+
+if __name__ == '__main__':
+    if 0:
+        test()
+    else:
+        parser = parse_args()
+        args = parser.parse_args()
+        now = datetime.datetime.utcnow()
+        args._date = now.isoformat()
+        do_command[args.command](args, dbname)