[Sqlalchemy-tickets] Issue #3921: problems creating records when table has compound primary key and server defaults set (zzzeek/sqlalchemy)

[Krzysztof M. <iss...@bi...>]

New issue 3921: problems creating records when table has compound primary key and server defaults set
https://bitbucket.org/zzzeek/sqlalchemy/issues/3921/problems-creating-records-when-table-has

Krzysztof Malinowski:

```
#!python
# -*- coding: utf-8 -*-

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

engine = create_engine('sqlite:///foo.db')
Base = declarative_base()

Session = sessionmaker(bind=engine)
session = Session()


class Project(Base):

    __tablename__ = 'project'

    id_ = Column(Integer, primary_key=True, unique=True, nullable=False)


class User(Base):

    __tablename__ = 'user'

    id_ = Column(Integer, primary_key=True, unique=True, nullable=False)


class TS(Base):

    __tablename__ = 'timesheet'
    __table_args__ = (
        PrimaryKeyConstraint('user_id', 'project_id', 'date'),
        UniqueConstraint('user_id', 'project_id', 'date')
    )

    user_id = Column(Integer, ForeignKey("user.id_"), nullable=False)
    project_id = Column(Integer, ForeignKey("project.id_"), nullable=False)
    # date = Column(DateTime, server_default=text('CURRENT_TIMESTAMP'), nullable=False)  # mysql ver.
    date = Column(DateTime, server_default=text("(datetime('now','localtime'))"), nullable=False)  # sqlite ver.


Base.metadata.create_all(engine)

u1 = User(id_=1)
p1 = Project(id_=1)
ts1 = TS(user_id=u1.id_, project_id=p1.id_)
session.add(u1)
session.add(p1)
session.add(ts1)
session.flush()
session.commit()

# let's try accesing ts1.date
print ts1.date
```
and we get the following traceback:


```
Traceback (most recent call last):
  File "composite_pk.py", line 90, in <module>
    print ts1.date
  File "/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py", line 237, in __get__
    return self.impl.get(instance_state(instance), dict_)
  File "/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py", line 578, in get
    value = state._load_expired(state, passive)
  File "/lib/python2.7/site-packages/sqlalchemy/orm/state.py", line 474, in _load_expired
    self.manager.deferred_scalar_loader(self, toload)
  File "/lib/python2.7/site-packages/sqlalchemy/orm/loading.py", line 669, in load_scalar_attributes
    raise orm_exc.ObjectDeletedError(state)
sqlalchemy.orm.exc.ObjectDeletedError: Instance '<TS at 0x7fd96e705650>' has been deleted, or its row is otherwise not present.

```

But when we look into the db table - the object has been created correctly. When the *date* column is not part of the compound PK this work just fine. The same happens on a MySQL backend.