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