Am 25.01.2011 um 14:36 schrieb luc:
Hi,
consider the following model. After the following pattern of code:
memento(m1) #####
memento(m2)
....
session.commit()
I get an exception whose traceback runs through the places I marked
with #####
sqlalchemy.exc.IntegrityError: (IntegrityError)
xxx_chemical_element.symbol may not be NULL u'INSERT INTO
xxx_chemical_element DEFAULT VALUES' ()
but I fail to see where a chemical_element could be created without
its attribute symbol getting a non-trivial value. And no, the argument
symbol below is a non-trivial string.
class chemical_element(Entity):
symbol = Field(String, primary_key=True)
mementoes = ManyToMany('memento')
def __init__(self, symbol):
if not self.get_by(symbol=symbol) is None: #####
self.symbol = symbol
class space_group(Entity):
number = Field(Integer)
hall = Field(String, primary_key=True)
mementoes = OneToMany('memento')
def __init__(self, space_group_info):
self.number = space_group_info.type().number()
self.hall = space_group_info.type().hall_symbol()
class memento(Entity):
name = Field(String, primary_key=True)
pickle = Field(PickleType)
space_group = ManyToOne('space_group')
chemical_elements = ManyToMany('chemical_element')
def __init__(self, m):
self.name = m.name
self.pickle = m
self.space_group = space_group(m.expected_sgi)
for e in m.asymmetric_unit_formula.iterkeys():
self.chemical_elements.append(chemical_element(symbol=e)) #####
I had problems when being to crazy with constructors. The least thing
you are missing here is that you do not call super.__init__. And you
possibly need a session.flush() to persist the actual entity before
putting more stuff there.
In general, it's good advice to not do more than providing default
values in constructors.
Diez
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