Source Code for Module daklib.database.base

 1  # This program is free software; you can redistribute it and/or modify 
 2  # it under the terms of the GNU General Public License as published by 
 3  # the Free Software Foundation; either version 2 of the License, or 
 4  # (at your option) any later version. 
 5   
 6  # This program is distributed in the hope that it will be useful, 
 7  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
 8  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 9  # GNU General Public License for more details. 
10   
11  # You should have received a copy of the GNU General Public License 
12  # along with this program; if not, write to the Free Software 
13  # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
14   
15  ################################################################################ 
16   
17  from sqlalchemy import Column, DateTime 
18  from sqlalchemy.event import listen 
19  from sqlalchemy.ext.declarative import declarative_base 
20  from sqlalchemy.schema import DDL, Table 
21  from sqlalchemy.sql import func 
22   
23   
24  Base = declarative_base() 
25   
26   
27 -class BaseMethods(Base): 
28      __abstract__ = True 
29   
30      @classmethod 
31 -    def get(cls, primary_key, session): 
32          ''' 
33          This is a support function that allows getting an object by its primary 
34          key. 
35   
36          Architecture.get(3[, session]) 
37   
38          instead of the more verbose 
39   
40          session.query(Architecture).get(3) 
41          ''' 
42          return session.query(cls).get(primary_key) 
43   
44   
45 -class BaseTimestamp(BaseMethods): 
46      __abstract__ = True 
47   
48      created = Column(DateTime(timezone=True), nullable=False, server_default=func.now()) 
49      modified = Column(DateTime(timezone=True), nullable=False, server_default=func.now()) 
50   
51      modified_trigger_function = DDL(""" 
52  CREATE OR REPLACE FUNCTION tfunc_set_modified() RETURNS trigger 
53  LANGUAGE plpgsql 
54  AS $$ 
55      BEGIN NEW.modified = now(); return NEW; END; 
56  $$ 
57      """) 
58   
59      modified_trigger = DDL(""" 
60  CREATE TRIGGER %(table)s_modified BEFORE UPDATE ON %(fullname)s 
61  FOR EACH ROW EXECUTE PROCEDURE tfunc_set_modified() 
62      """) 
63   
64      @classmethod 
65 -    def __table_cls__(cls, *arg, **kw): 
66          table = Table(*arg, **kw) 
67          listen( 
68              table, 
69              'after_create', 
70              cls.modified_trigger_function.execute_if(dialect='postgresql'), 
71          ) 
72          listen( 
73              table, 
74              'after_create', 
75              cls.modified_trigger.execute_if(dialect='postgresql'), 
76          ) 
77          return table 
78