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# sqlalchemy/naming.py
# Copyright (C) 2005-2014 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
"""Establish constraint and index naming conventions.
"""
from .schema import Constraint, ForeignKeyConstraint, PrimaryKeyConstraint, \
UniqueConstraint, CheckConstraint, Index, Table, Column
from .. import event, events
from .. import exc
from .elements import _truncated_label
import re
class conv(_truncated_label):
"""Mark a string indicating that a name has already been converted
by a naming convention.
This is a string subclass that indicates a name that should not be
subject to any further naming conventions.
E.g. when we create a :class:`.Constraint` using a naming convention
as follows::
m = MetaData(naming_convention={"ck": "ck_%(table_name)s_%(constraint_name)s"})
t = Table('t', m, Column('x', Integer),
CheckConstraint('x > 5', name='x5'))
The name of the above constraint will be rendered as ``"ck_t_x5"``. That is,
the existing name ``x5`` is used in the naming convention as the ``constraint_name``
token.
In some situations, such as in migration scripts, we may be rendering
the above :class:`.CheckConstraint` with a name that's already been
converted. In order to make sure the name isn't double-modified, the
new name is applied using the :func:`.schema.conv` marker. We can
use this explicitly as follows::
m = MetaData(naming_convention={"ck": "ck_%(table_name)s_%(constraint_name)s"})
t = Table('t', m, Column('x', Integer),
CheckConstraint('x > 5', name=conv('ck_t_x5')))
Where above, the :func:`.schema.conv` marker indicates that the constraint
name here is final, and the name will render as ``"ck_t_x5"`` and not
``"ck_t_ck_t_x5"``
.. versionadded:: 0.9.4
.. seealso::
:ref:`constraint_naming_conventions`
"""
class ConventionDict(object):
def __init__(self, const, table, convention):
self.const = const
self._is_fk = isinstance(const, ForeignKeyConstraint)
self.table = table
self.convention = convention
self._const_name = const.name
def _key_table_name(self):
return self.table.name
def _column_X(self, idx):
if self._is_fk:
fk = self.const.elements[idx]
return fk.parent
else:
return list(self.const.columns)[idx]
def _key_constraint_name(self):
if not self._const_name:
raise exc.InvalidRequestError(
"Naming convention including "
"%(constraint_name)s token requires that "
"constraint is explicitly named."
)
if not isinstance(self._const_name, conv):
self.const.name = None
return self._const_name
def _key_column_X_name(self, idx):
return self._column_X(idx).name
def _key_column_X_label(self, idx):
return self._column_X(idx)._label
def _key_referred_table_name(self):
fk = self.const.elements[0]
refs = fk.target_fullname.split(".")
if len(refs) == 3:
refschema, reftable, refcol = refs
else:
reftable, refcol = refs
return reftable
def _key_referred_column_X_name(self, idx):
fk = self.const.elements[idx]
refs = fk.target_fullname.split(".")
if len(refs) == 3:
refschema, reftable, refcol = refs
else:
reftable, refcol = refs
return refcol
def __getitem__(self, key):
if key in self.convention:
return self.convention[key](self.const, self.table)
elif hasattr(self, '_key_%s' % key):
return getattr(self, '_key_%s' % key)()
else:
col_template = re.match(r".*_?column_(\d+)_.+", key)
if col_template:
idx = col_template.group(1)
attr = "_key_" + key.replace(idx, "X")
idx = int(idx)
if hasattr(self, attr):
return getattr(self, attr)(idx)
raise KeyError(key)
_prefix_dict = {
Index: "ix",
PrimaryKeyConstraint: "pk",
CheckConstraint: "ck",
UniqueConstraint: "uq",
ForeignKeyConstraint: "fk"
}
def _get_convention(dict_, key):
for super_ in key.__mro__:
if super_ in _prefix_dict and _prefix_dict[super_] in dict_:
return dict_[_prefix_dict[super_]]
elif super_ in dict_:
return dict_[super_]
else:
return None
@event.listens_for(Constraint, "after_parent_attach")
@event.listens_for(Index, "after_parent_attach")
def _constraint_name(const, table):
if isinstance(table, Column):
# for column-attached constraint, set another event
# to link the column attached to the table as this constraint
# associated with the table.
event.listen(table, "after_parent_attach",
lambda col, table: _constraint_name(const, table)
)
elif isinstance(table, Table):
metadata = table.metadata
convention = _get_convention(metadata.naming_convention, type(const))
if convention is not None:
if const.name is None or "constraint_name" in convention:
newname = conv(
convention % ConventionDict(const, table, metadata.naming_convention)
)
if const.name is None:
const.name = newname
|
