full support for select() to accept mapped entities as from/correlate/etc.

[Mike Bayer]

since we don't want to hardcode something like __clause_element__() onto a mapped class, we would need some kind of registration where class_mapper() could be called as part of what expression uses to receive FROM arguments.

[Mike Bayer]

also document this case from #2530:

from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

class SnortEvent(Base):
    __tablename__ = "event"

    id = Column(Integer, primary_key=True)
    signature = Column(Integer, ForeignKey("signature.id"))

    signatures = relationship("Signature", lazy=False)

class Signature(Base):
    __tablename__ = "signature"

    id = Column(Integer, primary_key=True)

    sig_count = column_property(
                    select([func.count('*')](func.count('*'))).\
                        where(SnortEvent.signature == id).
                        correlate_except(SnortEvent)
                )

# workaround
#Signature.sig_count = column_property(
#                    select([func.count('*')](func.count('*'))).\
#                        where(SnortEvent.signature == Signature.id).\
#                        correlate(Signature.__table__)
#                )

session = Session()

print session.query(SnortEvent)

[Mike Bayer]

that is, the docs for column_property() should express correlate_except() in all those cases.

[Mike Bayer]

patch attached.

[Mike Bayer]

65bdf245c6cfd4381f8463714fbec1880a950fbb 37ced0946c4717422f8a4cc6ce4de1bd78ee942e, the doc thing is ee0f80b4f028e27f35ae851e37e4070a9179b2a1

[Mike Bayer]

Removing milestone: 0.8.0b1 (automated comment)