On Wed, Aug 24, 2016 at 2:55 AM, Jinghui Niu <niujing...@gmail.com> wrote:
> Hi, I wonder if there is any recommendation or best practice on choosing
> between
> hybrid_property
>
> and
> hybrid_method
> ,
> other than they hybrid_method can take arguments? If I use the hybrid_method
> only throughout, without giving it a argument more than self, doesn't it
> equal to using hybrid_property? Thanks.
It's the same trade-off as using normal python properties vs methods.
For properties, the underlying code is executed when the attribute is
accessed, whereas methods are executed when they are *called*. For
example, if you had this:
class Interval(Base):
__tablename__ = 'interval'
id = Column(Integer, primary_key=True)
start = Column(Integer, nullable=False)
end = Column(Integer, nullable=False)
def __init__(self, start, end):
self.start = start
self.end = end
@hybrid_property
def length_property(self):
return self.end - self.start
@hybrid_method
def length_method(self):
return self.end - self.start
...then you could query using the property like this:
session.query(Interval).filter(Interval.length_property > 5)
But the method would have to be used like this:
session.query(Interval).filter(Interval.length_method() > 5)
It's up to you which you prefer.
Hope that helps,
Simon
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