# ext/declarative/base.py
# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Internal implementation for declarative."""
from ...schema import Table, Column
from ...orm import mapper, class_mapper
from ...orm.interfaces import MapperProperty
from ...orm.properties import ColumnProperty, CompositeProperty
from ...orm.util import _is_mapped_class
from ... import util, exc
from ...sql import expression
from ... import event
from . import clsregistry
def _declared_mapping_info(cls):
# deferred mapping
if cls in _MapperConfig.configs:
return _MapperConfig.configs[cls]
# regular mapping
elif _is_mapped_class(cls):
return class_mapper(cls, configure=False)
else:
return None
def _as_declarative(cls, classname, dict_):
from .api import declared_attr
# dict_ will be a dictproxy, which we can't write to, and we need to!
dict_ = dict(dict_)
column_copies = {}
potential_columns = {}
mapper_args_fn = None
table_args = inherited_table_args = None
tablename = None
declarative_props = (declared_attr, util.classproperty)
for base in cls.__mro__:
_is_declarative_inherits = hasattr(base, '_decl_class_registry')
if '__declare_last__' in base.__dict__:
@event.listens_for(mapper, "after_configured")
def go():
cls.__declare_last__()
if '__abstract__' in base.__dict__:
if (base is cls or
(base in cls.__bases__ and not _is_declarative_inherits)
):
return
class_mapped = _declared_mapping_info(base) is not None
for name, obj in vars(base).items():
if name == '__mapper_args__':
if not mapper_args_fn and (
not class_mapped or
isinstance(obj, declarative_props)
):
# don't even invoke __mapper_args__ until
# after we've determined everything about the
# mapped table.
mapper_args_fn = lambda: cls.__mapper_args__
elif name == '__tablename__':
if not tablename and (
not class_mapped or
isinstance(obj, declarative_props)
):
tablename = cls.__tablename__
elif name == '__table_args__':
if not table_args and (
not class_mapped or
isinstance(obj, declarative_props)
):
table_args = cls.__table_args__
if not isinstance(table_args, (tuple, dict, type(None))):
raise exc.ArgumentError(
"__table_args__ value must be a tuple, "
"dict, or None")
if base is not cls:
inherited_table_args = True
elif class_mapped:
if isinstance(obj, declarative_props):
util.warn("Regular (i.e. not __special__) "
"attribute '%s.%s' uses @declared_attr, "
"but owning class %s is mapped - "
"not applying to subclass %s."
% (base.__name__, name, base, cls))
continue
elif base is not cls:
# we're a mixin.
if isinstance(obj, Column):
if getattr(cls, name) is not obj:
# if column has been overridden
# (like by the InstrumentedAttribute of the
# superclass), skip
continue
if obj.foreign_keys:
raise exc.InvalidRequestError(
"Columns with foreign keys to other columns "
"must be declared as @declared_attr callables "
"on declarative mixin classes. ")
if name not in dict_ and not (
'__table__' in dict_ and
(obj.name or name) in dict_['__table__'].c
) and name not in potential_columns:
potential_columns[name] = \
column_copies[obj] = \
obj.copy()
column_copies[obj]._creation_order = \
obj._creation_order
elif isinstance(obj, MapperProperty):
raise exc.InvalidRequestError(
"Mapper properties (i.e. deferred,"
"column_property(), relationship(), etc.) must "
"be declared as @declared_attr callables "
"on declarative mixin classes.")
elif isinstance(obj, declarative_props):
dict_[name] = ret = \
column_copies[obj] = getattr(cls, name)
if isinstance(ret, (Column, MapperProperty)) and \
ret.doc is None:
ret.doc = obj.__doc__
# apply inherited columns as we should
for k, v in potential_columns.items():
dict_[k] = v
if inherited_table_args and not tablename:
table_args = None
clsregistry.add_class(classname, cls)
our_stuff = util.OrderedDict()
for k in list(dict_):
# TODO: improve this ? all dunders ?
if k in ('__table__', '__tablename__', '__mapper_args__'):
continue
value = dict_[k]
if isinstance(value, declarative_props):
value = getattr(cls, k)
if (isinstance(value, tuple) and len(value) == 1 and
isinstance(value[0], (Column, MapperProperty))):
util.warn("Ignoring declarative-like tuple value of attribute "
"%s: possibly a copy-and-paste error with a comma "
"left at the end of the line?" % k)
continue
if not isinstance(value, (Column, MapperProperty)):
if not k.startswith('__'):
dict_.pop(k)
setattr(cls, k, value)
continue
if k == 'metadata':
raise exc.InvalidRequestError(
"Attribute name 'metadata' is reserved "
"for the MetaData instance when using a "
"declarative base class."
)
prop = clsregistry._deferred_relationship(cls, value)
our_stuff[k] = prop
# set up attributes in the order they were created
our_stuff.sort(key=lambda key: our_stuff[key]._creation_order)
# extract columns from the class dict
declared_columns = set()
for key, c in our_stuff.iteritems():
if isinstance(c, (ColumnProperty, CompositeProperty)):
for col in c.columns:
if isinstance(col, Column) and \
col.table is None:
_undefer_column_name(key, col)
declared_columns.add(col)
elif isinstance(c, Column):
_undefer_column_name(key, c)
declared_columns.add(c)
# if the column is the same name as the key,
# remove it from the explicit properties dict.
# the normal rules for assigning column-based properties
# will take over, including precedence of columns
# in multi-column ColumnProperties.
if key == c.key:
del our_stuff[key]
declared_columns = sorted(
declared_columns, key=lambda c: c._creation_order)
table = None
if hasattr(cls, '__table_cls__'):
table_cls = util.unbound_method_to_callable(cls.__table_cls__)
else:
table_cls = Table
if '__table__' not in dict_:
if tablename is not None:
args, table_kw = (), {}
if table_args:
if isinstance(table_args, dict):
table_kw = table_args
elif isinstance(table_args, tuple):
if isinstance(table_args[-1], dict):
args, table_kw = table_args[0:-1], table_args[-1]
else:
args = table_args
autoload = dict_.get('__autoload__')
if autoload:
table_kw['autoload'] = True
cls.__table__ = table = table_cls(
tablename, cls.metadata,
*(tuple(declared_columns) + tuple(args)),
**table_kw)
else:
table = cls.__table__
if declared_columns:
for c in declared_columns:
if not table.c.contains_column(c):
raise exc.ArgumentError(
"Can't add additional column %r when "
"specifying __table__" % c.key
)
if hasattr(cls, '__mapper_cls__'):
mapper_cls = util.unbound_method_to_callable(cls.__mapper_cls__)
else:
mapper_cls = mapper
for c in cls.__bases__:
if _declared_mapping_info(c) is not None:
inherits = c
break
else:
inherits = None
if table is None and inherits is None:
raise exc.InvalidRequestError(
"Class %r does not have a __table__ or __tablename__ "
"specified and does not inherit from an existing "
"table-mapped class." % cls
)
elif inherits:
inherited_mapper = _declared_mapping_info(inherits)
inherited_table = inherited_mapper.local_table
inherited_mapped_table = inherited_mapper.mapped_table
if table is None:
# single table inheritance.
# ensure no table args
if table_args:
raise exc.ArgumentError(
"Can't place __table_args__ on an inherited class "
"with no table."
)
# add any columns declared here to the inherited table.
for c in declared_columns:
if c.primary_key:
raise exc.ArgumentError(
"Can't place primary key columns on an inherited "
"class with no table."
)
if c.name in inherited_table.c:
if inherited_table.c[c.name] is c:
continue
raise exc.ArgumentError(
"Column '%s' on class %s conflicts with "
"existing column '%s'" %
(c, cls, inherited_table.c[c.name])
)
inherited_table.append_column(c)
if inherited_mapped_table is not None and \
inherited_mapped_table is not inherited_table:
inherited_mapped_table._refresh_for_new_column(c)
mt = _MapperConfig(mapper_cls,
cls, table,
inherits,
declared_columns,
column_copies,
our_stuff,
mapper_args_fn)
if not hasattr(cls, '_sa_decl_prepare'):
mt.map()
class _MapperConfig(object):
configs = util.OrderedDict()
mapped_table = None
def __init__(self, mapper_cls,
cls,
table,
inherits,
declared_columns,
column_copies,
properties, mapper_args_fn):
self.mapper_cls = mapper_cls
self.cls = cls
self.local_table = table
self.inherits = inherits
self.properties = properties
self.mapper_args_fn = mapper_args_fn
self.declared_columns = declared_columns
self.column_copies = column_copies
self.configs[cls] = self
def _prepare_mapper_arguments(self):
properties = self.properties
if self.mapper_args_fn:
mapper_args = self.mapper_args_fn()
else:
mapper_args = {}
# make sure that column copies are used rather
# than the original columns from any mixins
for k in ('version_id_col', 'polymorphic_on',):
if k in mapper_args:
v = mapper_args[k]
mapper_args[k] = self.column_copies.get(v, v)
assert 'inherits' not in mapper_args, \
"Can't specify 'inherits' explicitly with declarative mappings"
if self.inherits:
mapper_args['inherits'] = self.inherits
if self.inherits and not mapper_args.get('concrete', False):
# single or joined inheritance
# exclude any cols on the inherited table which are
# not mapped on the parent class, to avoid
# mapping columns specific to sibling/nephew classes
inherited_mapper = _declared_mapping_info(self.inherits)
inherited_table = inherited_mapper.local_table
if 'exclude_properties' not in mapper_args:
mapper_args['exclude_properties'] = exclude_properties = \
set([c.key for c in inherited_table.c
if c not in inherited_mapper._columntoproperty])
exclude_properties.difference_update(
[c.key for c in self.declared_columns])
# look through columns in the current mapper that
# are keyed to a propname different than the colname
# (if names were the same, we'd have popped it out above,
# in which case the mapper makes this combination).
# See if the superclass has a similar column property.
# If so, join them together.
for k, col in properties.items():
if not isinstance(col, expression.ColumnElement):
continue
if k in inherited_mapper._props:
p = inherited_mapper._props[k]
if isinstance(p, ColumnProperty):
# note here we place the subclass column
# first. See [ticket:1892] for background.
properties[k] = [col] + p.columns
result_mapper_args = mapper_args.copy()
result_mapper_args['properties'] = properties
return result_mapper_args
def map(self):
self.configs.pop(self.cls, None)
mapper_args = self._prepare_mapper_arguments()
self.cls.__mapper__ = self.mapper_cls(
self.cls,
self.local_table,
**mapper_args
)
def _add_attribute(cls, key, value):
"""add an attribute to an existing declarative class.
This runs through the logic to determine MapperProperty,
adds it to the Mapper, adds a column to the mapped Table, etc.
"""
if '__mapper__' in cls.__dict__:
if isinstance(value, Column):
_undefer_column_name(key, value)
cls.__table__.append_column(value)
cls.__mapper__.add_property(key, value)
elif isinstance(value, ColumnProperty):
for col in value.columns:
if isinstance(col, Column) and col.table is None:
_undefer_column_name(key, col)
cls.__table__.append_column(col)
cls.__mapper__.add_property(key, value)
elif isinstance(value, MapperProperty):
cls.__mapper__.add_property(
key,
clsregistry._deferred_relationship(cls, value)
)
else:
type.__setattr__(cls, key, value)
else:
type.__setattr__(cls, key, value)
def _declarative_constructor(self, **kwargs):
"""A simple constructor that allows initialization from kwargs.
Sets attributes on the constructed instance using the names and
values in ``kwargs``.
Only keys that are present as
attributes of the instance's class are allowed. These could be,
for example, any mapped columns or relationships.
"""
cls_ = type(self)
for k in kwargs:
if not hasattr(cls_, k):
raise TypeError(
"%r is an invalid keyword argument for %s" %
(k, cls_.__name__))
setattr(self, k, kwargs[k])
_declarative_constructor.__name__ = '__init__'
def _undefer_column_name(key, column):
if column.key is None:
column.key = key
if column.name is None:
column.name = key