How to specify an association relation using declarative base
- by sam
I have been trying to create an association relation between two tables, intake and module . Each intake has a one-to-many relationship with the modules.
However there is a coursework assigned to each module, and each coursework has a duedate which is unique to each intake.
I tried this but it didnt work:
intake_modules_table = Table('tg_intakemodules',metadata,
Column('intake_id',Integer,ForeignKey('tg_intake.intake_id',
onupdate="CASCADE",ondelete="CASCADE")),
Column('module_id',Integer,ForeignKey('tg_module.module_id',
onupdate ="CASCADE",ondelete="CASCADE")),
Column('dueddate', Unicode(16))
)
class Intake(DeclarativeBase):
__tablename__ = 'tg_intake'
#{ Columns
intake_id = Column(Integer, autoincrement=True, primary_key=True)
code = Column(Unicode(16))
commencement = Column(DateTime)
completion = Column(DateTime)
#{ Special methods
def __repr__(self):
return '"%s"' %self.code
def __unicode__(self):
return self.code
#}
class Module(DeclarativeBase):
__tablename__ ='tg_module'
#{ Columns
module_id = Column(Integer, autoincrement=True, primary_key=True)
code = Column(Unicode(16))
title = Column(Unicode(30))
#{ relations
intakes = relation('Intake',
secondary=intake_modules_table, backref='modules')
#{ Special methods
def __repr__(self):
return '"%s"'%self.title
def __unicode__(self):
return '"%s"'%self.title
#}
When I do this the column duedate specified in the intake_module_table is not created.
Please some help will be appreciated here.
thanks in advance
