SQLAlchemy Mapping problem
- by asdvalkn
Dear Everyone,
I am trying to sqlalchemy to correctly map my data. Note that a unified group is basically a group of groups. (One unifiedGroup maps to many groups but each group can only map to one ug).
So basically this is the definition of my unifiedGroups:
CREATE TABLE `unifiedGroups` (
`ugID` INT AUTO_INCREMENT,
`gID` INT NOT NULL,
PRIMARY KEY(`ugID`, `gID`),
KEY( `gID`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8
;
Note that each row is a ugID, gID tuple. ( I do not know before hand how many gID is per ugID so this is probably the most sensible and simplest method).
Definition for my UnifiedGroup class
class UnifiedGroup(object):
"""UnifiedProduct behaves very much like a group
"""
def __init__(self, ugID):
self.ugID=ugID
#Added by mapping
self.groups=False
def __str__(self):
return '<%s:%s>' % (self.ugID, ','.join( [g for g in self.groups]))
These are my mapping tables:
tb_groupsInfo = Table( 'groupsInfo', metadata,
Column('gID', Integer, primary_key=True),
Column('gName', String(128)),
)
tb_unifiedGroups = Table( 'unifiedGroups', metadata,
Column('ugID', Integer, primary_key=True),
Column('gID', Integer, ForeignKey('groupsInfo.gID')),
)
My mapper maps in the following manner:
mapper( UnifiedGroup, tb_unifiedGroups, properties={
'groups': relation( Group, backref='unifiedGroup')
})
However, when I tried to do groupInstance.unifiedGroup, I am getting an empty list [],
while groupInstance.unifiedGroup.groups returns me an error:
AttributeError: 'InstrumentedList' object has no attribute 'groups'
Traceback (most recent call last):
File "Mapping.py", line 119, in <module>
print p.group.unifiedGroup.groups
AttributeError: 'InstrumentedList' object has no attribute 'groups'
What is wrong?
