вторник, 14 марта 2017 г., 17:15:25 UTC+3 пользователь Mike Bayer написал:
>
>
>
> On 03/14/2017 10:02 AM, Антонио Антуан wrote:
> > Hi.
> > I use sqlalchemy 1.0.17, thanks for you great library :)
> >
> > I have such code:
> > |
> >
> >
> > classFlagsMixin(object):
> > @hybrid_method
> > defexist_flag(self,flag):
> > ifnotself.flags ornotflag:
> > returnFalse
> > returnself.flags &flag ==flag
> >
> > @exist_flag.expression
> > defexist_flag(self,flag):
> > returnand_(flag !=0,self.flags !=0,self.flags.op('&')(flag)!=0)
> >
> >
> > classSomeModel(Base,FlagsMixin,AnyOtherClass):
> > # class attrs and methods
> >
> > |
> >
> >
> > In case of optimization, I want to create sqlalchemy-free class,
>
> what sort of optimization? are you having a performance problem?
>
Just hardcode optimization, no preformance problems, don't worry :)
>
>
> which
> > contains all methods and attributes of class. So, i wrote that code:
> >
> > |
> >
> >
> > @staticmethod
> > def_get_sa_free_class(klass,with_mro=False):
> > sa_free_cls =getattr(klass,'__sa_free_cls',None)
> >
> > ifsa_free_cls isNone:
> > items ={}
> > klasses =[klass]ifnotwith_mro elseklass.__mro__
> > fork inklasses:
> > forname,val ink.__dict__.items():
> > ifname notinitems andname
> >
> notin['__mapper__','__dict__','__class__','_sa_class_manager','query','metadata']:
>
>
> > ifisinstance(val,InstrumentedAttribute):
> > items[name]=None
> > else:
> > items[name]=val
> > formethod_name in('exist_flag',):
> > items[method_name]=getattr(klass,method_name)
> > sa_free_cls
> =type('Unbound'+klass.__name__,(object,),dict(items))
> > sa_free_cls._sa_free =True
> >
> > sa_free_cls.__init__
> =klass._sa_class_manager.original_init.im_func
> >
> > setattr(klass,'__sa_free_cls',sa_free_cls)
> > returnsa_free_cls
>
> So what you're trying to do is: 1. create a class 2. map it 3. then
> extract it into something unmapped. this seems backwards. Why not
> create your class as "unmapped", then make a subclass of it that is
> mapped?
>
>
> class MyOptimizedClass(FlagsMixin):
> # stuff
>
>
> class MyMappedClass(MyOptimizedClass, Base):
> __tablename__ = ...
>
> # stuff
>
>
> Or something like that, where you make use of your descriptor
> declaration directly instead of reverse engineering it.
>
> > Result class should has `exist_flag()` method, and it has to be used
> > always with `func` attribute of hybrid_property, neither `expr` (as I
> > want to have SQLA-free class).
> >
> > As you can see, I want to ensure `exist_flag()` method existence in
> > result `klass` object, and if method called with `with_mro=False`.
> > But, of course, such a way can't allow this, because of descriptor logic
> > - return `expr` if instance not specified:
> >
> > |
> > klass.exist_flag(1)
> > <sqlalchemy.sql.elements.BooleanClauseList object at 0x7f2a79b835d0>
> >
> > |
> >
> > Also, I tried to use this versions with same result -
> AttributeError(''):
> >
> >
> > |
> > klass.exist_flag.func
> > klass.exist_flag.__class__.func
>
> well when you access the hybrid like that it gets invoked. you'd need
> to get it either as:
>
> hybrid = klass.__class__.__dict__['exist_flag']
>
> >>> getattr(klass, 'exist_flag')
<bound method DeclarativeMeta.exist_flag of <class
'hasoffers.core.model.offer.Offer'>>
>>>
>>> klass.__class__.__dict__['exist_flag']
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
KeyError: 'exist_flag'
> or
>
> from sqlalchemy import inspect
> mapper = inspect(klass)
> hybrid = mapper.all_orm_descriptors.exist_flag
>
>
> you probably want to be using mapper.all_orm_descriptors to help with
> your inspection.
>
Yes, it helps, thank you :)
>
> > ...
> >
> > AttributeError: 'function' object has no attribute 'func'
> >
> > |
> >
> > Is there any way to get `func` attribute of hybrid_method?
> > And also, maybe sqlalchemy already has some alternative to get
> > sqla-free-class?
> >
> > Thank you again.
> > Anton.
> >
> > --
> > SQLAlchemy -
> > The Python SQL Toolkit and Object Relational Mapper
> >
> > http://www.sqlalchemy.org/
> >
> > To post example code, please provide an MCVE: Minimal, Complete, and
> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> > description.
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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