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  Base = declarative_base() 
24   
25   
26 -class BaseMethods(Base): 
27      __abstract__ = True 
28   
29      @classmethod 
30 -    def get(cls, primary_key, session): 
31          """ 
32          This is a support function that allows getting an object by its primary 
33          key. 
34   
35          Architecture.get(3[, session]) 
36   
37          instead of the more verbose 
38   
39          session.query(Architecture).get(3) 
40          """ 
41          return session.query(cls).get(primary_key) 
42   
43   
44 -class BaseTimestamp(BaseMethods): 
45      __abstract__ = True 
46   
47      created = Column(DateTime(timezone=True), nullable=False, server_default=func.now()) 
48      modified = Column( 
49          DateTime(timezone=True), nullable=False, server_default=func.now() 
50      ) 
51   
52      modified_trigger_function = DDL( 
53          """ 
54  CREATE OR REPLACE FUNCTION tfunc_set_modified() RETURNS trigger 
55  LANGUAGE plpgsql 
56  AS $$ 
57      BEGIN NEW.modified = now(); return NEW; END; 
58  $$ 
59      """ 
60      ) 
61   
62      modified_trigger = DDL( 
63          """ 
64  CREATE TRIGGER %(table)s_modified BEFORE UPDATE ON %(fullname)s 
65  FOR EACH ROW EXECUTE PROCEDURE tfunc_set_modified() 
66      """ 
67      ) 
68   
69      @classmethod 
70 -    def __table_cls__(cls, *arg, **kw): 
71          table = Table(*arg, **kw) 
72          listen( 
73              table, 
74              "after_create", 
75              cls.modified_trigger_function.execute_if(dialect="postgresql"), 
76          ) 
77          listen( 
78              table, 
79              "after_create", 
80              cls.modified_trigger.execute_if(dialect="postgresql"), 
81          ) 
82          return table 
83