635 lines
20 KiB
Python
635 lines
20 KiB
Python
# sql/base.py
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# Copyright (C) 2005-2016 the SQLAlchemy authors and contributors
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# <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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"""Foundational utilities common to many sql modules.
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"""
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from .. import util, exc
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import itertools
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from .visitors import ClauseVisitor
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import re
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import collections
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PARSE_AUTOCOMMIT = util.symbol('PARSE_AUTOCOMMIT')
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NO_ARG = util.symbol('NO_ARG')
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class Immutable(object):
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"""mark a ClauseElement as 'immutable' when expressions are cloned."""
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def unique_params(self, *optionaldict, **kwargs):
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raise NotImplementedError("Immutable objects do not support copying")
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def params(self, *optionaldict, **kwargs):
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raise NotImplementedError("Immutable objects do not support copying")
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def _clone(self):
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return self
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def _from_objects(*elements):
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return itertools.chain(*[element._from_objects for element in elements])
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@util.decorator
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def _generative(fn, *args, **kw):
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"""Mark a method as generative."""
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self = args[0]._generate()
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fn(self, *args[1:], **kw)
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return self
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class _DialectArgView(collections.MutableMapping):
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"""A dictionary view of dialect-level arguments in the form
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<dialectname>_<argument_name>.
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"""
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def __init__(self, obj):
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self.obj = obj
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def _key(self, key):
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try:
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dialect, value_key = key.split("_", 1)
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except ValueError:
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raise KeyError(key)
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else:
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return dialect, value_key
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def __getitem__(self, key):
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dialect, value_key = self._key(key)
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try:
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opt = self.obj.dialect_options[dialect]
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except exc.NoSuchModuleError:
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raise KeyError(key)
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else:
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return opt[value_key]
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def __setitem__(self, key, value):
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try:
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dialect, value_key = self._key(key)
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except KeyError:
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raise exc.ArgumentError(
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"Keys must be of the form <dialectname>_<argname>")
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else:
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self.obj.dialect_options[dialect][value_key] = value
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def __delitem__(self, key):
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dialect, value_key = self._key(key)
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del self.obj.dialect_options[dialect][value_key]
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def __len__(self):
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return sum(len(args._non_defaults) for args in
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self.obj.dialect_options.values())
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def __iter__(self):
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return (
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util.safe_kwarg("%s_%s" % (dialect_name, value_name))
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for dialect_name in self.obj.dialect_options
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for value_name in
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self.obj.dialect_options[dialect_name]._non_defaults
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)
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class _DialectArgDict(collections.MutableMapping):
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"""A dictionary view of dialect-level arguments for a specific
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dialect.
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Maintains a separate collection of user-specified arguments
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and dialect-specified default arguments.
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"""
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def __init__(self):
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self._non_defaults = {}
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self._defaults = {}
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def __len__(self):
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return len(set(self._non_defaults).union(self._defaults))
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def __iter__(self):
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return iter(set(self._non_defaults).union(self._defaults))
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def __getitem__(self, key):
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if key in self._non_defaults:
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return self._non_defaults[key]
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else:
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return self._defaults[key]
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def __setitem__(self, key, value):
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self._non_defaults[key] = value
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def __delitem__(self, key):
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del self._non_defaults[key]
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class DialectKWArgs(object):
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"""Establish the ability for a class to have dialect-specific arguments
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with defaults and constructor validation.
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The :class:`.DialectKWArgs` interacts with the
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:attr:`.DefaultDialect.construct_arguments` present on a dialect.
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.. seealso::
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:attr:`.DefaultDialect.construct_arguments`
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"""
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@classmethod
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def argument_for(cls, dialect_name, argument_name, default):
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"""Add a new kind of dialect-specific keyword argument for this class.
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E.g.::
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Index.argument_for("mydialect", "length", None)
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some_index = Index('a', 'b', mydialect_length=5)
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The :meth:`.DialectKWArgs.argument_for` method is a per-argument
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way adding extra arguments to the
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:attr:`.DefaultDialect.construct_arguments` dictionary. This
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dictionary provides a list of argument names accepted by various
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schema-level constructs on behalf of a dialect.
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New dialects should typically specify this dictionary all at once as a
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data member of the dialect class. The use case for ad-hoc addition of
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argument names is typically for end-user code that is also using
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a custom compilation scheme which consumes the additional arguments.
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:param dialect_name: name of a dialect. The dialect must be
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locatable, else a :class:`.NoSuchModuleError` is raised. The
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dialect must also include an existing
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:attr:`.DefaultDialect.construct_arguments` collection, indicating
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that it participates in the keyword-argument validation and default
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system, else :class:`.ArgumentError` is raised. If the dialect does
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not include this collection, then any keyword argument can be
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specified on behalf of this dialect already. All dialects packaged
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within SQLAlchemy include this collection, however for third party
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dialects, support may vary.
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:param argument_name: name of the parameter.
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:param default: default value of the parameter.
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.. versionadded:: 0.9.4
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"""
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construct_arg_dictionary = DialectKWArgs._kw_registry[dialect_name]
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if construct_arg_dictionary is None:
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raise exc.ArgumentError(
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"Dialect '%s' does have keyword-argument "
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"validation and defaults enabled configured" %
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dialect_name)
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if cls not in construct_arg_dictionary:
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construct_arg_dictionary[cls] = {}
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construct_arg_dictionary[cls][argument_name] = default
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@util.memoized_property
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def dialect_kwargs(self):
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"""A collection of keyword arguments specified as dialect-specific
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options to this construct.
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The arguments are present here in their original ``<dialect>_<kwarg>``
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format. Only arguments that were actually passed are included;
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unlike the :attr:`.DialectKWArgs.dialect_options` collection, which
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contains all options known by this dialect including defaults.
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The collection is also writable; keys are accepted of the
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form ``<dialect>_<kwarg>`` where the value will be assembled
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into the list of options.
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.. versionadded:: 0.9.2
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.. versionchanged:: 0.9.4 The :attr:`.DialectKWArgs.dialect_kwargs`
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collection is now writable.
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.. seealso::
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:attr:`.DialectKWArgs.dialect_options` - nested dictionary form
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"""
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return _DialectArgView(self)
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@property
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def kwargs(self):
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"""A synonym for :attr:`.DialectKWArgs.dialect_kwargs`."""
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return self.dialect_kwargs
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@util.dependencies("sqlalchemy.dialects")
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def _kw_reg_for_dialect(dialects, dialect_name):
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dialect_cls = dialects.registry.load(dialect_name)
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if dialect_cls.construct_arguments is None:
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return None
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return dict(dialect_cls.construct_arguments)
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_kw_registry = util.PopulateDict(_kw_reg_for_dialect)
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def _kw_reg_for_dialect_cls(self, dialect_name):
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construct_arg_dictionary = DialectKWArgs._kw_registry[dialect_name]
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d = _DialectArgDict()
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if construct_arg_dictionary is None:
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d._defaults.update({"*": None})
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else:
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for cls in reversed(self.__class__.__mro__):
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if cls in construct_arg_dictionary:
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d._defaults.update(construct_arg_dictionary[cls])
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return d
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@util.memoized_property
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def dialect_options(self):
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"""A collection of keyword arguments specified as dialect-specific
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options to this construct.
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This is a two-level nested registry, keyed to ``<dialect_name>``
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and ``<argument_name>``. For example, the ``postgresql_where``
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argument would be locatable as::
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arg = my_object.dialect_options['postgresql']['where']
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.. versionadded:: 0.9.2
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.. seealso::
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:attr:`.DialectKWArgs.dialect_kwargs` - flat dictionary form
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"""
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return util.PopulateDict(
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util.portable_instancemethod(self._kw_reg_for_dialect_cls)
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)
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def _validate_dialect_kwargs(self, kwargs):
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# validate remaining kwargs that they all specify DB prefixes
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if not kwargs:
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return
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for k in kwargs:
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m = re.match('^(.+?)_(.+)$', k)
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if not m:
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raise TypeError(
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"Additional arguments should be "
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"named <dialectname>_<argument>, got '%s'" % k)
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dialect_name, arg_name = m.group(1, 2)
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try:
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construct_arg_dictionary = self.dialect_options[dialect_name]
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except exc.NoSuchModuleError:
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util.warn(
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"Can't validate argument %r; can't "
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"locate any SQLAlchemy dialect named %r" %
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(k, dialect_name))
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self.dialect_options[dialect_name] = d = _DialectArgDict()
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d._defaults.update({"*": None})
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d._non_defaults[arg_name] = kwargs[k]
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else:
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if "*" not in construct_arg_dictionary and \
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arg_name not in construct_arg_dictionary:
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raise exc.ArgumentError(
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"Argument %r is not accepted by "
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"dialect %r on behalf of %r" % (
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k,
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dialect_name, self.__class__
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))
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else:
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construct_arg_dictionary[arg_name] = kwargs[k]
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class Generative(object):
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"""Allow a ClauseElement to generate itself via the
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@_generative decorator.
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"""
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def _generate(self):
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s = self.__class__.__new__(self.__class__)
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s.__dict__ = self.__dict__.copy()
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return s
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class Executable(Generative):
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"""Mark a ClauseElement as supporting execution.
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:class:`.Executable` is a superclass for all "statement" types
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of objects, including :func:`select`, :func:`delete`, :func:`update`,
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:func:`insert`, :func:`text`.
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"""
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supports_execution = True
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_execution_options = util.immutabledict()
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_bind = None
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@_generative
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def execution_options(self, **kw):
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""" Set non-SQL options for the statement which take effect during
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execution.
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Execution options can be set on a per-statement or
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per :class:`.Connection` basis. Additionally, the
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:class:`.Engine` and ORM :class:`~.orm.query.Query` objects provide
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access to execution options which they in turn configure upon
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connections.
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The :meth:`execution_options` method is generative. A new
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instance of this statement is returned that contains the options::
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statement = select([table.c.x, table.c.y])
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statement = statement.execution_options(autocommit=True)
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Note that only a subset of possible execution options can be applied
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to a statement - these include "autocommit" and "stream_results",
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but not "isolation_level" or "compiled_cache".
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See :meth:`.Connection.execution_options` for a full list of
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possible options.
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.. seealso::
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:meth:`.Connection.execution_options()`
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:meth:`.Query.execution_options()`
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"""
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if 'isolation_level' in kw:
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raise exc.ArgumentError(
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"'isolation_level' execution option may only be specified "
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"on Connection.execution_options(), or "
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"per-engine using the isolation_level "
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"argument to create_engine()."
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)
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if 'compiled_cache' in kw:
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raise exc.ArgumentError(
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"'compiled_cache' execution option may only be specified "
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"on Connection.execution_options(), not per statement."
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)
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self._execution_options = self._execution_options.union(kw)
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def execute(self, *multiparams, **params):
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"""Compile and execute this :class:`.Executable`."""
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e = self.bind
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if e is None:
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label = getattr(self, 'description', self.__class__.__name__)
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msg = ('This %s is not directly bound to a Connection or Engine.'
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'Use the .execute() method of a Connection or Engine '
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'to execute this construct.' % label)
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raise exc.UnboundExecutionError(msg)
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return e._execute_clauseelement(self, multiparams, params)
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def scalar(self, *multiparams, **params):
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"""Compile and execute this :class:`.Executable`, returning the
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result's scalar representation.
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"""
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return self.execute(*multiparams, **params).scalar()
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@property
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def bind(self):
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"""Returns the :class:`.Engine` or :class:`.Connection` to
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which this :class:`.Executable` is bound, or None if none found.
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This is a traversal which checks locally, then
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checks among the "from" clauses of associated objects
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until a bound engine or connection is found.
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"""
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if self._bind is not None:
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return self._bind
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for f in _from_objects(self):
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if f is self:
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continue
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engine = f.bind
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if engine is not None:
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return engine
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else:
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return None
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class SchemaEventTarget(object):
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"""Base class for elements that are the targets of :class:`.DDLEvents`
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events.
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This includes :class:`.SchemaItem` as well as :class:`.SchemaType`.
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"""
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def _set_parent(self, parent):
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"""Associate with this SchemaEvent's parent object."""
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raise NotImplementedError()
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def _set_parent_with_dispatch(self, parent):
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self.dispatch.before_parent_attach(self, parent)
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self._set_parent(parent)
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self.dispatch.after_parent_attach(self, parent)
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class SchemaVisitor(ClauseVisitor):
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"""Define the visiting for ``SchemaItem`` objects."""
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__traverse_options__ = {'schema_visitor': True}
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class ColumnCollection(util.OrderedProperties):
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"""An ordered dictionary that stores a list of ColumnElement
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instances.
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Overrides the ``__eq__()`` method to produce SQL clauses between
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sets of correlated columns.
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"""
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__slots__ = '_all_columns'
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def __init__(self, *columns):
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super(ColumnCollection, self).__init__()
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object.__setattr__(self, '_all_columns', [])
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for c in columns:
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self.add(c)
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def __str__(self):
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return repr([str(c) for c in self])
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def replace(self, column):
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"""add the given column to this collection, removing unaliased
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versions of this column as well as existing columns with the
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same key.
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e.g.::
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t = Table('sometable', metadata, Column('col1', Integer))
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t.columns.replace(Column('col1', Integer, key='columnone'))
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will remove the original 'col1' from the collection, and add
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the new column under the name 'columnname'.
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Used by schema.Column to override columns during table reflection.
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"""
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remove_col = None
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if column.name in self and column.key != column.name:
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other = self[column.name]
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if other.name == other.key:
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remove_col = other
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del self._data[other.key]
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if column.key in self._data:
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remove_col = self._data[column.key]
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self._data[column.key] = column
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if remove_col is not None:
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self._all_columns[:] = [column if c is remove_col
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else c for c in self._all_columns]
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else:
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self._all_columns.append(column)
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def add(self, column):
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"""Add a column to this collection.
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The key attribute of the column will be used as the hash key
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for this dictionary.
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"""
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if not column.key:
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raise exc.ArgumentError(
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"Can't add unnamed column to column collection")
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self[column.key] = column
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def __delitem__(self, key):
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raise NotImplementedError()
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def __setattr__(self, key, object):
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raise NotImplementedError()
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def __setitem__(self, key, value):
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if key in self:
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# this warning is primarily to catch select() statements
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# which have conflicting column names in their exported
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# columns collection
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existing = self[key]
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if not existing.shares_lineage(value):
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util.warn('Column %r on table %r being replaced by '
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'%r, which has the same key. Consider '
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'use_labels for select() statements.' %
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(key, getattr(existing, 'table', None), value))
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# pop out memoized proxy_set as this
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# operation may very well be occurring
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# in a _make_proxy operation
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util.memoized_property.reset(value, "proxy_set")
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self._all_columns.append(value)
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self._data[key] = value
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def clear(self):
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raise NotImplementedError()
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def remove(self, column):
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del self._data[column.key]
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self._all_columns[:] = [
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c for c in self._all_columns if c is not column]
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def update(self, iter):
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cols = list(iter)
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all_col_set = set(self._all_columns)
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self._all_columns.extend(
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c for label, c in cols if c not in all_col_set)
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self._data.update((label, c) for label, c in cols)
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def extend(self, iter):
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cols = list(iter)
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all_col_set = set(self._all_columns)
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self._all_columns.extend(c for c in cols if c not in all_col_set)
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self._data.update((c.key, c) for c in cols)
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|
|
|
__hash__ = None
|
|
|
|
@util.dependencies("sqlalchemy.sql.elements")
|
|
def __eq__(self, elements, other):
|
|
l = []
|
|
for c in getattr(other, "_all_columns", other):
|
|
for local in self._all_columns:
|
|
if c.shares_lineage(local):
|
|
l.append(c == local)
|
|
return elements.and_(*l)
|
|
|
|
def __contains__(self, other):
|
|
if not isinstance(other, util.string_types):
|
|
raise exc.ArgumentError("__contains__ requires a string argument")
|
|
return util.OrderedProperties.__contains__(self, other)
|
|
|
|
def __getstate__(self):
|
|
return {'_data': self._data,
|
|
'_all_columns': self._all_columns}
|
|
|
|
def __setstate__(self, state):
|
|
object.__setattr__(self, '_data', state['_data'])
|
|
object.__setattr__(self, '_all_columns', state['_all_columns'])
|
|
|
|
def contains_column(self, col):
|
|
return col in set(self._all_columns)
|
|
|
|
def as_immutable(self):
|
|
return ImmutableColumnCollection(self._data, self._all_columns)
|
|
|
|
|
|
class ImmutableColumnCollection(util.ImmutableProperties, ColumnCollection):
|
|
def __init__(self, data, all_columns):
|
|
util.ImmutableProperties.__init__(self, data)
|
|
object.__setattr__(self, '_all_columns', all_columns)
|
|
|
|
extend = remove = util.ImmutableProperties._immutable
|
|
|
|
|
|
class ColumnSet(util.ordered_column_set):
|
|
def contains_column(self, col):
|
|
return col in self
|
|
|
|
def extend(self, cols):
|
|
for col in cols:
|
|
self.add(col)
|
|
|
|
def __add__(self, other):
|
|
return list(self) + list(other)
|
|
|
|
@util.dependencies("sqlalchemy.sql.elements")
|
|
def __eq__(self, elements, other):
|
|
l = []
|
|
for c in other:
|
|
for local in self:
|
|
if c.shares_lineage(local):
|
|
l.append(c == local)
|
|
return elements.and_(*l)
|
|
|
|
def __hash__(self):
|
|
return hash(tuple(x for x in self))
|
|
|
|
|
|
def _bind_or_error(schemaitem, msg=None):
|
|
bind = schemaitem.bind
|
|
if not bind:
|
|
name = schemaitem.__class__.__name__
|
|
label = getattr(schemaitem, 'fullname',
|
|
getattr(schemaitem, 'name', None))
|
|
if label:
|
|
item = '%s object %r' % (name, label)
|
|
else:
|
|
item = '%s object' % name
|
|
if msg is None:
|
|
msg = "%s is not bound to an Engine or Connection. "\
|
|
"Execution can not proceed without a database to execute "\
|
|
"against." % item
|
|
raise exc.UnboundExecutionError(msg)
|
|
return bind
|