Re: [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
    Resolution:               |   Keywords:
Progress State:  in queue     |
------------------------------+-------------------------------
Description changed by zzzeek:

Old description:

> {{{
> #!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()
> }}}

New description:

 {{{
 #!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(),
                         server_onupdate=FetchedValue())

     __mapper_args__ = {
         "version_id_col": version_id,
         "version_id_generator": lambda val: None,
         # "eager_defaults": True  # should not be needed
     }

 # should work whether or not this is set
 #    __table_args__ = {"implicit_returning": False}

 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#comment:2>
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