Does SQLAlchemy offer a generic way to get the primary key from a declaratively defined instance, so that if:

Base = declarative_base()class MyClass(Base):__tablename__ = 'mytable'key = Column(Integer, primary_key=True)

I can do:

>>> a = MyClass(key=1)
>>> a.generic_get_primary_key()  # <-- does it exist ??
1

You can use inspection for that purpose:

http://docs.sqlalchemy.org/en/latest/core/inspection.html

Passing an instance of a mapped object to inspect, returns an InstanceState, describing that object. This state also contains the identity:

Base = declarative_base()class MyClass(Base):__tablename__ = 'mytable'key = Column(Integer, primary_key=True)
a = MyClass(key=1)from sqlalchemy.inspection import inspect    
pk = inspect(a).identity
print pk

Will give:

(1,)

Since primary keys can consist of multiple columns, the identity in general is a tuple containing all the column values that are part of the primary key. In your case, that's simply the key.