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Archived:A simple ORM SQL for PySymbian

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Created: cyke64 (31 Mar 2007)
Last edited: hamishwillee (31 May 2013)

This simple Object Relational Mapper is adapted from SQLAlchemy and SQLObject. You need to create a database manually first.

from __future__ import generators
import e32db, re
db = e32db.Dbms()
dbv = e32db.Db_view()
db.open(u'C:\\test.db')
 
# Some helping classes (need more in next version)
class String:
pass
 
class Integer:
pass
 
class Float:
pass
 
class column:
def __init__(self, coltype):
self.coltype = coltype
 
class Mapper(object):
def __init__(self, id=None, **kw):
if id is None:
self.id = self._insert(**kw)
else:
self.id = id
def _insert(self, **kw):
names = ','.join(kw.keys())
values = ','.join(self.quote(k,v) for k,v in kw.items())
tablename = self.__class__.__name__
q = u"INSERT INTO %s(%s) VALUES (%s)" % (tablename, names, values)
db.execute(q)
# get last insert ID
dbv.prepare(db, u'SELECT id FROM '+tablename+' ORDER BY id DESC')
dbv.first_line()
dbv.get_line()
return dbv.col(1)
def __getattr__(self, name):
if hasattr(self.mapping, name):
q = 'SELECT '+name+' FROM '+self.__class__.__name__
q += ' WHERE id='+str(self.id)
dbv.prepare(db, unicode(q))
dbv.first_line()
dbv.get_line()
return dbv.col(1)
else:
return self.__dict__[name]
def __repr__(self):
return '<%s id=%d>' % (self.__class__.__name__, self.id)
def quote(self, name, value):
if getattr(self.mapping, name).coltype == String:
return "'%s'" % value.replace("'", "''") # encode single quote
else:
return str(value)
def __setattr__(self, name, value):
if hasattr(self.mapping, name):
q = 'UPDATE '+self.__class__.__name__+' SET '+name+'='
q += self.quote(name, value) + " WHERE id=" + str(self.id)
db.execute(unicode(q))
else:
self.__dict__[name] = value
def set(self, **kw):
q = "UPDATE "+self.__class__.__name__+" SET "
for k, v in kw.items():
q += k+'='+self.quote(k,v)+','
q = q[:-1]+" WHERE id=%s" % self.id
db.execute(unicode(q))
def delete(self):
q = 'DELETE FROM '+self.__class__.__name__+" WHERE id=" + str(self.id)
db.execute(unicode(q))
self.id = None
def dict(self):
names = [k for k in self.mapping.__dict__ if not k.startswith('__')]
q = 'SELECT '+','.join(names)+' FROM '+self.__class__.__name__
q += ' WHERE id=' + str(self.id)
dbv.prepare(db, unicode(q))
dbv.first_line()
dbv.get_line()
dct = {'id': self.id}
for i in range(dbv.col_count()):
dct[names[i]] = dbv.col(i+1)
return dct
def select(cls, where=None, orderby=None):
q = 'SELECT id FROM '+cls.__name__
if where:
q += ' WHERE '+where
if orderby:
q += ' ORDER BY '+orderby
dbv = e32db.Db_view() # need its own cursor
dbv.prepare(db, unicode(q))
dbv.first_line()
for i in range(dbv.count_line()):
dbv.get_line()
yield cls(dbv.col(1))
dbv.next_line()
select = classmethod(select)

Here's how you create your class.

class Phone(Mapper):
class mapping:
# doesn't need id = column(Integer)
name = column(String)
edition = column(Integer)
This page was last modified on 31 May 2013, at 04:02.
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