[Sqlalchemy-tickets] [sqlalchemy] #2820: session.merge/nullable primary keys - FlushError: Can't update table using NULL for primary key value

[sqlalchemy <mi...@zz...>]

#2820: session.merge/nullable primary keys - FlushError: Can't update table using
NULL for primary key value
------------------------+-----------------------------------------
 Reporter:  elsdoerfer  |           Owner:  zzzeek
     Type:  defect      |          Status:  new
 Priority:  medium      |       Milestone:
Component:  orm         |        Severity:  no triage selected yet
 Keywords:              |  Progress State:  awaiting triage
------------------------+-----------------------------------------
 SQLAlchemy==0.8.2

 I believe this is a bug:

 {{{
 Traceback (most recent call last):
   File "test.py", line 42, in <module>
     session.commit()
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/orm/session.py", line 721, in commit
     self.transaction.commit()
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/orm/session.py", line 354, in commit
     self._prepare_impl()
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/orm/session.py", line 334, in _prepare_impl
     self.session.flush()
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/orm/session.py", line 1818, in flush
     self._flush(objects)
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/orm/session.py", line 1936, in _flush
     transaction.rollback(_capture_exception=True)
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/util/langhelpers.py", line 58, in __exit__
     compat.reraise(exc_type, exc_value, exc_tb)
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/orm/session.py", line 1900, in _flush
     flush_context.execute()
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/orm/unitofwork.py", line 372, in execute
     rec.execute(self)
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/orm/unitofwork.py", line 525, in execute
     uow
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/orm/persistence.py", line 54, in save_obj
     table, states_to_update)
   File "/Users/michael/.virtualenvs/cms/lib/python2.7/site-
 packages/sqlalchemy/orm/persistence.py", line 383, in
 _collect_update_commands
     "Can't update table "
 sqlalchemy.orm.exc.FlushError: Can't update table using NULL for primary
 key value
 }}}

 This is the code that triggers this:

 {{{
 from sqlalchemy import *
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker, relationship

 engine = create_engine('sqlite:///:memory:', echo=True)
 Session = sessionmaker(bind=engine)
 session = Session()

 Base = declarative_base()

 class Related(Base):
     __tablename__ = 'related'
     parent = Column(Integer, ForeignKey("parent.id"))
     key1 = Column(Integer, primary_key=True, nullable=True)
     key2 = Column(Integer, primary_key=True, nullable=True)

     def __init__(self, key1, key2):
         self.key1, self.key2 = key1, key2

 class Parent(Base):
     __tablename__ = 'parent'
     id = Column(Integer, primary_key=True)
     related = relationship(Related, collection_class=set)

 Base.metadata.create_all(engine)

 # First object
 parent = Parent()
 parent.id = 1
 parent.related.add(Related(3, None))
 session.add(parent)
 session.commit()

 # Update first object
 parent = Parent()
 parent.id = 1
 parent.related.add(Related(2, None))
 session.merge(parent)
 session.commit()
 }}}

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Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2820>
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