I´ve sent them to the list a few days ago. It is a modification to
ActiveMapper (mostly to the process_relationships function and a bit of
change in ActiveMapperMeta) to allow for multiple relationships between
classes as we discussed earlier in this list. It mostly separates tables
creation from relationships processing, while shuffling these in the
proper order so there are no conflicts when they are created. I can
re-send my original message if it has not arrived. I´ve tested this
modification in a real application case with 20 tables with multiple
references to each other and it seems to be working ok...
Anyway, this is the code....
activemapper.py
---BEGIN---
from sqlalchemy import objectstore, create_engine,
assign_mapper, relation, mapper
from sqlalchemy import and_, or_
from sqlalchemy import Table, Column, ForeignKey
from sqlalchemy.ext.proxy import ProxyEngine
import inspect
import sys
#
# the "proxy" to the database engine... this can be swapped out at runtime
#
engine = ProxyEngine()
#
# declarative column declaration - this is so that we can infer the colname
#
class column(object):
def __init__(self, coltype, colname=None, foreign_key=None,
primary_key=False, *args, **kwargs):
if isinstance( foreign_key, basestring ):
foreign_key= ForeignKey( foreign_key )
self.coltype = coltype
self.colname = colname
self.foreign_key = foreign_key
self.primary_key = primary_key
# self.unique = kwargs.pop( 'unique', None )
# self.index = kwargs.pop( 'indexed', None )
self.kwargs = kwargs
self.args = args
#
# declarative relationship declaration
#
class relationship(object):
def __init__(self, classname, colname=None, backref=None, private=False,
lazy=True, uselist=True, secondary=None):
self.classname = classname
self.colname = colname
self.backref = backref
self.private = private
self.lazy = lazy
self.uselist = uselist
self.secondary = secondary
class one_to_many(relationship):
def __init__(self, classname, colname=None, backref=None,
private=False, lazy=True):
relationship.__init__(self, classname, colname, backref,
private, lazy, uselist=True)
class one_to_one(relationship):
def __init__(self, classname, colname=None, backref=None,
private=False, lazy=True):
relationship.__init__(self, classname, colname, backref,
private, lazy, uselist=False)
class many_to_many(relationship):
def __init__(self, classname, secondary, backref=None, lazy=True):
relationship.__init__(self, classname, None, backref, False, lazy,
uselist=True, secondary=secondary)
#
# SQLAlchemy metaclass and superclass that can be used to do SQLAlchemy
# mapping in a declarative way, along with a function to process the
# relationships between dependent objects as they come in, without blowing
# up if the classes aren't specified in a proper order
#
__deferred_classes__ = []
__processed_classes__ = []
def check_relationships(klass):
#Check the class for foreign_keys recursively. If some foreign table
is not found, the processing of the table
#must be defered.
for keyname in klass.table._foreign_keys:
xtable = keyname._colspec[:keyname._colspec.find('.')]
tablefound = False
for xclass in ActiveMapperMeta.classes:
if ActiveMapperMeta.classes[xclass].table.from_name == xtable:
tablefound = True
break
if tablefound==False:
#The refered table has not yet been created.
return False
return True
def process_relationships(klass):
defer = False
for propname, reldesc in klass.relations.items():
#We require that every related table has been processed first
if not reldesc.classname in __processed_classes__:
if not klass._classname in __deferred_classes__:
__deferred_classes__.append(klass._classname)
defer = True
#Check every column item to see if it points to an existing table
#if it does not, defer...
if not defer:
if not check_relationships(klass):
if not klass._classname in __deferred_classes__:
__deferred_classes__.append(klass._classname)
defer = True
if not defer:
relations = {}
__processed_classes__.append(klass._classname)
for propname, reldesc in klass.relations.items():
relclass = ActiveMapperMeta.classes[reldesc.classname]
relations[propname] = relation(relclass.mapper,
secondary=reldesc.secondary,
backref=reldesc.backref,
private=reldesc.private,
lazy=reldesc.lazy,
uselist=reldesc.uselist)
if len(relations)>0:
assign_mapper(klass, klass.table, properties=relations)
if klass._classname in __deferred_classes__:
__deferred_classes__.remove(klass._classname)
for deferred_class in __deferred_classes__:
process_relationships(ActiveMapperMeta.classes[deferred_class])
class ActiveMapperMeta(type):
classes = {}
def __init__(cls, clsname, bases, dict):
table_name = clsname.lower()
columns = []
relations = {}
_engine = getattr( sys.modules[cls.__module__], "__engine__",
engine )
if 'mapping' in dict:
members = inspect.getmembers(dict.get('mapping'))
for name, value in members:
if name == '__table__':
table_name = value
continue
if '__engine__' == name:
_engine= value
continue
if name.startswith('__'): continue
if isinstance(value, column):
if value.foreign_key:
col = Column(value.colname or name,
value.coltype,
value.foreign_key,
primary_key=value.primary_key,
*value.args, **value.kwargs)
else:
col = Column(value.colname or name,
value.coltype,
primary_key=value.primary_key,
*value.args, **value.kwargs)
columns.append(col)
# if value.indexed:
# # create a Index object for the column
# index= Index( "%s_idx" % (value.colname or name),
# col, unique= value.unique )
continue
if isinstance(value, relationship):
relations[name] = value
assert _engine is not None, "No engine specified"
cls.table = Table(table_name, _engine, *columns)
assign_mapper(cls, cls.table)
cls.relations = relations
cls._classname = clsname
ActiveMapperMeta.classes[clsname] = cls
process_relationships(cls)
super(ActiveMapperMeta, cls).__init__(clsname, bases, dict)
class ActiveMapper(object):
__metaclass__ = ActiveMapperMeta
def set(self, **kwargs):
for key, value in kwargs.items():
setattr(self, key, value)
#
# a utility function to create all tables for all ActiveMapper classes
#
def create_tables():
for klass in ActiveMapperMeta.classes.values():
klass.table.create()
---END---
Best Regards,
Gabriel.
Jeff Watkins escribió:
I'm not familiar with your changes. Have they been committed or are
they available in a patch somewhere?
On 9 Apr, 2006, at 6:56 pm, Gabriel Jacobo wrote:
Have you considered my changes to the process_relationships function
in Activemapper?
--
Jeff Watkins
http://newburyportion.com/
"Computers are like Old Testament gods; lots of rules and no mercy."
-- Joseph Campbell
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