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?
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']
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.
...
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 -
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http://www.sqlalchemy.org/
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SQLAlchemy -
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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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