lazy = 'dynamic' and coercing AppenderQuery to a new object class

[Zippy P]

Hi all,

I have the following:

class Device(Base):

...

  source_id = Column(BigInteger, primary_key=True)

...

class EventQuery(Query):

  def custommethod():

    ...

class Event(Base):

  __tablename__ = 'events'

  query = Session.query.property(query_cls = EventQuery)

...

  device_source_id = Column(BigInteger, ForeignKey("Device.source_id"))

  device = relationship(Device, backref=backref('events', lazy='dynamic'))

...

Now, Device.events returns a query of type AppenderQuery, which is fine for some built-in methods like count() and all(). What I really need is for this to be a query of type EventQuery, so I can call Device.events.custommethod(). 

1) Is it possible to coerce AppenderQuery into a different Query class?

2) If not, is it appropriate to create a custom property on Device that will return an EventQuery containing the equivalent query, or is there a more proper way to do it?

Thanks,

S.

[Michael Bayer]

relationship() and backref() accept query_class for this purpose.

>
> Thanks,
>
> S.
>
>
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