[Sqlalchemy-tickets] Issue #4188: mapper places ConcreteInheritedProperty on top of a hybrid (zzzeek/sqlalchemy)

[Michael B. <iss...@bi...>]

New issue 4188: mapper places ConcreteInheritedProperty on top of a hybrid
https://bitbucket.org/zzzeek/sqlalchemy/issues/4188/mapper-places-concreteinheritedproperty-on

Michael Bayer:

```
#!python

from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.declarative import declared_attr
from sqlalchemy.ext.declarative import AbstractConcreteBase
from sqlalchemy.ext.hybrid import hybrid_property

Base = declarative_base()


class AbstractBase(AbstractConcreteBase, Base):
    @declared_attr
    def column1(cls):
        return Column(Integer)

    @declared_attr
    def column2(cls):
        return Column(Integer)


class Concrete1(AbstractBase):
    __tablename__ = "concrete1"

    id = Column(Integer, primary_key=True)

    attribute1 = Column(Integer)

    __mapper_args__ = {
        'polymorphic_identity': 'concrete1',
        'concrete': True
    }


class Concrete2(AbstractBase):
    __tablename__ = "concrete2"

    id = Column(Integer, primary_key=True)
    attribute2 = Column(Integer)

    @hybrid_property
    def attribute1(self):
        return self.attribute2

    @attribute1.expression
    def attribute1(cls):
        return cls.attribute2

    __mapper_args__ = {
        'polymorphic_identity': 'concrete2',
        'concrete': True
    }

print(Concrete2.attribute1.__clause_element__())
c2 = Concrete2(attribute2=5)
c2.attribute1
```

produces:

```
#!


concrete2.attribute2
Traceback (most recent call last):
  File "test.py", line 55, in <module>
    c2.attribute1
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/orm/attributes.py", line 298, in __get__
    return self.descriptor.__get__(instance, owner)
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/orm/descriptor_props.py", line 512, in __get__
    warn()
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/orm/descriptor_props.py", line 500, in warn
    (self.parent, self.key, self.parent))
AttributeError: Concrete Mapper|Concrete2|concrete2 does not implement attribute 'attribute1' at the instance level.  Add this property explicitly to Mapper|Concrete2|concrete2.

```

suggestion:

```
#!diff


diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index cd9e00b8b..31100d9c8 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -1612,7 +1612,7 @@ class Mapper(InspectionAttr):
     def _adapt_inherited_property(self, key, prop, init):
         if not self.concrete:
             self._configure_property(key, prop, init=False, setparent=False)
-        elif key not in self._props:
+        elif not isinstance(getattr(self.class_, key, None), InspectionAttr):
             self._configure_property(
                 key,
                 properties.ConcreteInheritedProperty(),
```