He Michael,
You saved me again .. Thanks!
On Apr 2, 2:09 am, Michael Bayer <mike...@zzzcomputing.com> wrote:
> On Apr 1, 2011, at 2:52 PM, farcat wrote:
>
> > Hi Michael,
>
> > Still stuck, I don't mixin foreign keys or relationships. When is a
> > Column attached to a table in declarative?
>
> so you have a few things like:
>
> > class AtomBase(BaseBase):
> > id = Column(Integer, primary_key=True)
>
> where AtomBase does not appear to be a declarative class. Its hard to follow
> but it appears AtomBase is taking the path that mixins take in declarative
> (indeed: "__new__(mcls, name, (AtomBase, Base)"). This means "id" will be
> copied for each actual declarative class generated from AtomBase.
>
> Later you have:
>
> > ForeignKey(parent.id),
>
> This is referencing an "id" column probably too early. In all likelihood It
> isn't being linked to a table, a copy of it is. Use
> ForeignKey("parent_table_name.id") instead so that the column is evaluated as
> late as possible.
>
>
>
>
>
>
>
> > My code is:
>
> > import datetime
> > from datatypes import *
> > from accessors import member_accessor, reference_accessor
>
> > from sqlalchemy import *
> > from sqlalchemy.orm import relationship
> > from sqlalchemy.orm.session import sessionmaker
> > from sqlalchemy.ext.declarative import declared_attr, DeclarativeMeta
> > from sqlalchemy.types import Text, BigInteger, Float, Boolean, Date,
> > Time
> > #--------------------------------------------------------------------------
> > -
> > engine = create_engine('sqlite:///:memory:', echo=False)
> > Session = sessionmaker(bind=engine)
> > register = dict()
>
> > #--------------------------------------------------------------------------
> > -
> > class BaseBase(object):
> > session = Session()
> > @declared_attr
> > def __tablename__(cls): return cls.__name__
> > def __init__(self, **kwargs):
> > Base.__init__(self, **kwargs)
> > self.session.add(self)
> > print str(self) + " added to session " + str(self.session)
> > def __repr__(self):
> > out = "type: " + type(self).__name__ + "{"
> > for name, mem in self.__dict__:
> > out += name + ": " + str(mem) + ", "
> > out += "}"
> > return out
>
> > #--------------------------------------------------------------------
> > class AtomBase(BaseBase):
> > id = Column(Integer, primary_key=True)
> > atomic = True
> > #--------------------------------------------------------------------
> > class atommeta(DeclarativeMeta):
> > def __new__(mcls, name, coltype):
> > return DeclarativeMeta.__new__(mcls, name, (AtomBase, Base),
> > {name:Column(coltype, nullable = False)})
> > def __init__(cls, name, coltype):
> > register[name] = cls
> > return DeclarativeMeta.__init__(cls, name, (AtomBase, Base),
> > {})
> > #--------------------------------------------------------------------------
> > -
> > class BaseLink(BaseBase):
>
> > member_name = Column(String(64), primary_key = True) #Name of
> > member of parent class
> > member_table = Column(String(64), primary_key = True) #Name of
> > table in which value of member resides
> > member_id = Column(Integer, primary_key = True) #record
> > is in member_table, with previous column enables polymorphism
> > def _getitem(self):
> > t = register[self.member_table]
> > return self.session.query(t).filter(self.member_id ==
> > t.id).one()
> > def _setitem(self, val):
> > try: del self.item
> > except AttributeError: pass
> > self.member_table = val.__tablename__
> > self.member_id = val.id
> > def _delitem(self):
> > t = register[self.member_table]
> > self.session.query(t).filter(t.id == self.member_id).delete()
> > item = property(_getitem, _setitem, _delitem)
> > #--------------------------------------------------------------------------
> > -
> > class BaseTable(BaseBase):
>
> > id = Column(Integer, primary_key = True)
> > created_at = Column(DateTime, default=datetime.datetime.now())
> > atomic = False
> > #--------------------------------------------------------------------------
> > -
> > class linkmeta(DeclarativeMeta):
> > def __new__(mcls, parent):
> > return DeclarativeMeta.__new__(mcls, "%s_links" %
> > parent.__name__, (BaseLink, Base),
> > {"parent_id": Column(Integer,
> > ForeignKey(parent.id), primary_key=True)})
> > def __init__(cls, parent):
> > return DeclarativeMeta.__init__(cls, "%s_links" %
> > parent.__name__, (BaseLink, Base), {})
> > #--------------------------------------------------------------------------
> > -
> > class tablemeta(DeclarativeMeta):
>
> > def __new__(mcls, typedef):
> > out = DeclarativeMeta.__new__(mcls, str(typedef.name),
> > (BaseTable,Base), {})
> > out.links = linkmeta(out) #<== Creates class/table enables
> > links to other tables
> > members = typedef.all()
> > for mem in members:
> > if not mem.type.name in register:
> > tablemeta(mem.type)
> > setattr(out, "_" + mem.name, relationship(out.links,
> > uselist =
> > (mem.multiplicity != "one"),
> > backref =
> > mem.name,
> > primaryjoin =
> > and_(out.links.parent_id == out.id,
>
> > out.links.member_name == mem.name)))
> > return out
> > def __init__(cls, typedef):
> > register[cls.__name__] = cls
> > temp = dict()
> > members = typedef.all()
> > for mem in members:
> > if mem.reference:
> > temp[mem.name] = reference_accessor(mem.name,
> > register[mem.type_name], mem.multiplicity)
> > else:
> > temp[mem.name] = member_accessor(mem.name,
> > register[mem.type_name], mem.multiplicity)
> > return DeclarativeMeta.__init__(cls, typedef.name,
> > (BaseTable,Base), temp)
> > #--------------------------------------------------------------------------
> > -
> > def createClasses(engine, session):
> > print "creating classes and tables"
> > atommeta("text", Text)
> > atommeta("integer", BigInteger)
> > atommeta("decimal", Float)
> > atommeta("boolean", Boolean)
> > atommeta("date", Date)
> > atommeta("time", Time)
> > typedefs = session.query(Type).filter(Type.atomic == False).all()
> > for typedef in typedefs:
> > tablemeta(typedef)
> > print
> > "--------------------------------------------------------------------------
> > ---------"
> > for reg in register:
> > print reg
> > Base.metadata.create_all(engine) #<== ERROR
> > print"done"
>
> > Please help ....
>
> > The typedefs variables describe classes and members, and are queried
> > from normal tables
>
> > On Mar 31, 5:33 pm, Michael Bayer <mike...@zzzcomputing.com> wrote:
> >> On Mar 31, 2011, at 11:29 AM, farcat wrote:
>
> >>> Hi,
>
> >>> I am getting the following error after creating a number of classes
> >>> through metaclasses:
>
> >>> File "C:\python27\lib\site-packages\sqlalchemy\dialects\sqlite
> >>> \base.py", line 280, in visit_foreign_key_constraint
> >>> if local_table.schema != remote_table.schema:
> >>> AttributeError: 'NoneType' object has no attribute 'schema'
>
> >>> Before I paste in any code (would need quite a lot), can anyone point
> >>> me in the right direction?
>
> >> There's a Column not attached to a Table somewhere. Like, if you are
> >> creating a copy of a column, giving that to a table, but then the original
> >> is what you put in ForeignKey.
>
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