Add the DatabaseOutOfDate exception instead of using ValueError.

timesearch/exceptions.py

@@ -15,5 +15,15 @@ class TimesearchException(Exception):
     def __str__(self):
         return self.error_message
 
+OUTOFDATE = '''
+Database is out of date. {current} should be {new}.
+Please use utilities\\database_upgrader.py
+'''.strip()
+class DatabaseOutOfDate(TimesearchException):
+    '''
+    Raised by TSDB __init__ if the user's database is behind.
+    '''
+    error_message = OUTOFDATE
+
 class DatabaseNotFound(TimesearchException, FileNotFoundError):
     error_message = 'Database file not found: "{}"'

timesearch/tsdb.py

@@ -73,10 +73,6 @@ CREATE TABLE IF NOT EXISTS comments(
 CREATE INDEX IF NOT EXISTS comment_index ON comments(idstr);
 '''.format(user_version=DATABASE_VERSION)
 
-ERROR_DATABASE_OUTOFDATE = '''
-Database is out of date. {current} should be {new}.
-'''.strip()
-
 DEFAULT_CONFIG = {
 }
 
@@ -143,9 +139,7 @@ class TSDB:
             self.cur.execute('PRAGMA user_version')
             existing_version = self.cur.fetchone()[0]
             if existing_version > 0 and existing_version != DATABASE_VERSION:
-                message = ERROR_DATABASE_OUTOFDATE
+                raise exceptions.DatabaseOutOfDate(current=existing_version, new=DATABASE_VERSION)
-                message = message.format(current=existing_version, new=DATABASE_VERSION)
-                raise ValueError(message)
 
         statements = DB_INIT.split(';')
         for statement in statements:

utilities/database_upgrader.py

@@ -0,0 +1,52 @@
+import argparse
+import os
+import sqlite3
+import sys
+
+import timesearch.tsdb
+
+
+def upgrade_all(database_filename):
+    '''
+    Given the filename of a database, apply all of the needed
+    upgrade_x_to_y functions in order.
+    '''
+    if not os.path.isfile(database_filename):
+        raise FileNotFoundError(database_filename)
+
+    sql = sqlite3.connect(database_filename)
+    cur = sql.cursor()
+
+    cur.execute('PRAGMA user_version')
+    current_version = cur.fetchone()[0]
+    needed_version = timesearch.tsdb.DATABASE_VERSION
+
+    if current_version == needed_version:
+        print('Already up to date with version %d.' % needed_version)
+        return
+
+    for version_number in range(current_version + 1, needed_version + 1):
+        print('Upgrading from %d to %d' % (current_version, version_number))
+        upgrade_function = 'upgrade_%d_to_%d' % (current_version, version_number)
+        upgrade_function = eval(upgrade_function)
+        upgrade_function(sql)
+        sql.cursor().execute('PRAGMA user_version = %d' % version_number)
+        sql.commit()
+        current_version = version_number
+    print('Upgrades finished.')
+
+
+def upgrade_all_argparse(args):
+    return upgrade_all(database_filename=args.database_filename)
+
+def main(argv):
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument('database_filename')
+    parser.set_defaults(func=upgrade_all_argparse)
+
+    args = parser.parse_args(argv)
+    args.func(args)
+
+if __name__ == '__main__':
+    main(sys.argv[1:])