[sqlalchemy] Inserting in a container class that behaves as list (or set) from the contained class (not from the container)
Hello list!
I have a couple of classes. One of the behaves as the container of the other:
class ContainerOfSamples(declarativeBase):
__tablename__ = containers
_id = Column(id, Integer, primary_key=True)
_samples = relationship(Samples, cascade=all, delete,
collection_class=set)
def setSamples(self, samples):
self._samples = samples
def getSamples(self):
return self._samples
def addSample(self, sample):
self._samples.add(sample)
id = sqlalchemy.orm.synonym('_id', descriptor=property(getId, setId))
samples = sqlalchemy.orm.synonym('_samples',
descriptor=property(getSamples,
setSamples))
class Sample(declarativeBase):
__tablename__ = containers
_id = Column(id, Integer, primary_key=True)
_whatever = Column(whatever, String(20))
_containerId = Column(container_id, Integer,
ForeignKey(containers.id))
_container = relationship(Container, uselist=False)
def __hash__(self):
return int(self.id)
def setContainer(self, container):
self._container = container
def getContainer(self):
return self._container
id = sqlalchemy.orm.synonym('_id', descriptor=property(getId, setId))
whatever = sqlalchemy.orm.synonym('_whatever',
descriptor=property(getWhatever,
setWhatever))
container = sqlalchemy.orm.synonym('_container',
descriptor=property(getContainer,
setContainer))
It's a relationship 1:N (one sample can be in 1 container, 1 container
can have N samples)... basically, a list...
If I have an instance of ContainerOfSamples and I want to add a
sample, I can do:
container = ContainerOfSamples()
sample = Sample()
container.addSample(sample)
And the sample is properly added, the relationships are all
initialized/created/set (however you want to call it) properly... the
containerId in the sample is the id of the container instance...
perfect.
So now the question is: Is there a way of getting the same effect from
the Sample class? Something like:
sample = Sample()
container = ContainerOfSamples()
sample.container(container)
And then in the container instance the Sample sample would be
added to the container.samples set?
It doesn't seem to work... for some reason, if I try to do that, the
sample._containerId becames the id of the sample...
I don't know if playing with the backref would give me what I
want... I've made a few tries, but it doesn't seem to improve... Maybe
I have a misconception here :-(
Any hints, examples, link to examples... would be helpful and deeply
appreciated. Thank you in advance!
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Re: [sqlalchemy] Inserting in a container class that behaves as list (or set) from the contained class (not from the container)
On Jan 21, 2011, at 12:29 PM, Hector Blanco wrote:
Hello list!
I have a couple of classes. One of the behaves as the container of the other:
class ContainerOfSamples(declarativeBase):
__tablename__ = containers
_id = Column(id, Integer, primary_key=True)
_samples = relationship(Samples, cascade=all, delete,
collection_class=set)
def setSamples(self, samples):
self._samples = samples
def getSamples(self):
return self._samples
def addSample(self, sample):
self._samples.add(sample)
id = sqlalchemy.orm.synonym('_id', descriptor=property(getId, setId))
samples = sqlalchemy.orm.synonym('_samples',
descriptor=property(getSamples,
setSamples))
class Sample(declarativeBase):
__tablename__ = containers
_id = Column(id, Integer, primary_key=True)
_whatever = Column(whatever, String(20))
_containerId = Column(container_id, Integer,
ForeignKey(containers.id))
_container = relationship(Container, uselist=False)
def __hash__(self):
return int(self.id)
def setContainer(self, container):
self._container = container
def getContainer(self):
return self._container
id = sqlalchemy.orm.synonym('_id', descriptor=property(getId, setId))
whatever = sqlalchemy.orm.synonym('_whatever',
descriptor=property(getWhatever,
setWhatever))
container = sqlalchemy.orm.synonym('_container',
descriptor=property(getContainer,
setContainer))
sample = Sample()
container = ContainerOfSamples()
sample.container(container)
I don't understand the need for the synonyms, but shouldn't this be as simple
as sample.container = container? The relationship on sample is already
defined... maybe you are confused because you think you need these getters and
setters- in the above example, I don't see any need for them.
Cheers,
M
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Re: [sqlalchemy] Inserting in a container class that behaves as list (or set) from the contained class (not from the container)
Thank you for the quick reply.
shouldn't this be as simple as sample.container = container
Yeah... I thought so too... And actually, the getter/setters (the
synonym or property) just do that... (and a check for the parameter
type):
class Sample(declarativeBase):
# yadda, yadda, yadda ...
def setContainer(self, container):
if isinstance(container, Container):
self._container = container
else:
raise TypeError(received a %s when expecting a
Container % type(container))
Anyway... if my idea is not wrong, I'll check if the error is
somewhere else. It's good to know that I'm going in the right
direction!
Thank you!
2011/1/21 A.M. age...@themactionfaction.com:
On Jan 21, 2011, at 12:29 PM, Hector Blanco wrote:
Hello list!
I have a couple of classes. One of the behaves as the container of the other:
class ContainerOfSamples(declarativeBase):
__tablename__ = containers
_id = Column(id, Integer, primary_key=True)
_samples = relationship(Samples, cascade=all, delete,
collection_class=set)
def setSamples(self, samples):
self._samples = samples
def getSamples(self):
return self._samples
def addSample(self, sample):
self._samples.add(sample)
id = sqlalchemy.orm.synonym('_id', descriptor=property(getId, setId))
samples = sqlalchemy.orm.synonym('_samples',
descriptor=property(getSamples,
setSamples))
class Sample(declarativeBase):
__tablename__ = containers
_id = Column(id, Integer, primary_key=True)
_whatever = Column(whatever, String(20))
_containerId = Column(container_id, Integer,
ForeignKey(containers.id))
_container = relationship(Container, uselist=False)
def __hash__(self):
return int(self.id)
def setContainer(self, container):
self._container = container
def getContainer(self):
return self._container
id = sqlalchemy.orm.synonym('_id', descriptor=property(getId, setId))
whatever = sqlalchemy.orm.synonym('_whatever',
descriptor=property(getWhatever,
setWhatever))
container = sqlalchemy.orm.synonym('_container',
descriptor=property(getContainer,
setContainer))
sample = Sample()
container = ContainerOfSamples()
sample.container(container)
I don't understand the need for the synonyms, but shouldn't this be as simple
as sample.container = container? The relationship on sample is already
defined... maybe you are confused because you think you need these getters
and setters- in the above example, I don't see any need for them.
Cheers,
M
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