[Sqlalchemy-tickets] [sqlalchemy] #2793: support server default for version_id_col

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

#2793: support server default for version_id_col
-------------------------+------------------------------------
 Reporter:  zzzeek       |           Owner:  zzzeek
     Type:  enhancement  |          Status:  new
 Priority:  medium       |       Milestone:  0.9.0
Component:  orm          |        Severity:  major - 1-3 hours
 Keywords:               |  Progress State:  in queue
-------------------------+------------------------------------
 {{{
 #!diff
 diff --git a/lib/sqlalchemy/orm/persistence.py
 b/lib/sqlalchemy/orm/persistence.py
 index 46b0be9..6013095 100644
 --- a/lib/sqlalchemy/orm/persistence.py
 +++ b/lib/sqlalchemy/orm/persistence.py
 @@ -248,7 +248,9 @@ def _collect_insert_commands(base_mapper,
 uowtransaction, table,
          has_all_pks = True
          for col in mapper._cols_by_table[table]:
              if col is mapper.version_id_col:
 -                params[col.key] = mapper.version_id_generator(None)
 +                val = mapper.version_id_generator(None)
 +                if val is not None:
 +                    params[col.key] = val
              else:
                  # pull straight from the dict for
                  # pending objects
 @@ -315,19 +317,21 @@ def _collect_update_commands(base_mapper,
 uowtransaction,
                      params[col.key] = history.added[0]
                      hasdata = True
                  else:
 -                    params[col.key] = mapper.version_id_generator(
 +                    val = mapper.version_id_generator(
                                                  params[col._label])
 -
 -                    # HACK: check for history, in case the
 -                    # history is only
 -                    # in a different table than the one
 -                    # where the version_id_col is.
 -                    for prop in mapper._columntoproperty.itervalues():
 -                        history = attributes.get_state_history(
 -                                state, prop.key,
 -                                attributes.PASSIVE_NO_INITIALIZE)
 -                        if history.added:
 -                            hasdata = True
 +                    if val is not None:
 +                        params[col.key] = val
 +
 +                        # HACK: check for history, in case the
 +                        # history is only
 +                        # in a different table than the one
 +                        # where the version_id_col is.
 +                        for prop in
 mapper._columntoproperty.itervalues():
 +                            history = attributes.get_state_history(
 +                                    state, prop.key,
 +                                    attributes.PASSIVE_NO_INITIALIZE)
 +                            if history.added:
 +                                hasdata = True
              else:
                  prop = mapper._columntoproperty[col]
                  history = attributes.get_state_history(
 }}}

 {{{
 #!python
 from sqlalchemy import *
 from sqlalchemy.orm import *
 from sqlalchemy.ext.declarative import declarative_base

 Base = declarative_base()


 class A(Base):
     __tablename__ = 'a'

     id = Column(Integer, primary_key=True)
     data = Column(String)
     version_id = Column('xmin', Integer, server_default=FetchedValue())

     __mapper_args__ = {
         "version_id_col": version_id,
         "version_id_generator": lambda val: None
     }

 engine = create_engine("postgresql://scott:tiger@localhost/test",
 echo=True)
 Base.metadata.drop_all(engine)
 engine.execute("create table a (id serial primary key, data varchar)")


 s = Session(engine)

 a1 = A(data='a1')

 s.add(a1)

 s.flush()

 a1.data = 'a2'

 s.flush()
 }}}

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Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2793>
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