1095 lines
37 KiB
Python
1095 lines
37 KiB
Python
# sql/ddl.py
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# Copyright (C) 2009-2016 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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"""
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Provides the hierarchy of DDL-defining schema items as well as routines
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to invoke them for a create/drop call.
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"""
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from .. import util
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from .elements import ClauseElement
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from .base import Executable, _generative, SchemaVisitor, _bind_or_error
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from ..util import topological
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from .. import event
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from .. import exc
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class _DDLCompiles(ClauseElement):
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def _compiler(self, dialect, **kw):
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"""Return a compiler appropriate for this ClauseElement, given a
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Dialect."""
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return dialect.ddl_compiler(dialect, self, **kw)
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class DDLElement(Executable, _DDLCompiles):
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"""Base class for DDL expression constructs.
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This class is the base for the general purpose :class:`.DDL` class,
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as well as the various create/drop clause constructs such as
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:class:`.CreateTable`, :class:`.DropTable`, :class:`.AddConstraint`,
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etc.
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:class:`.DDLElement` integrates closely with SQLAlchemy events,
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introduced in :ref:`event_toplevel`. An instance of one is
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itself an event receiving callable::
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event.listen(
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users,
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'after_create',
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AddConstraint(constraint).execute_if(dialect='postgresql')
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)
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.. seealso::
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:class:`.DDL`
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:class:`.DDLEvents`
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:ref:`event_toplevel`
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:ref:`schema_ddl_sequences`
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"""
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_execution_options = Executable.\
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_execution_options.union({'autocommit': True})
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target = None
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on = None
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dialect = None
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callable_ = None
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def _execute_on_connection(self, connection, multiparams, params):
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return connection._execute_ddl(self, multiparams, params)
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def execute(self, bind=None, target=None):
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"""Execute this DDL immediately.
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Executes the DDL statement in isolation using the supplied
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:class:`.Connectable` or
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:class:`.Connectable` assigned to the ``.bind``
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property, if not supplied. If the DDL has a conditional ``on``
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criteria, it will be invoked with None as the event.
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:param bind:
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Optional, an ``Engine`` or ``Connection``. If not supplied, a valid
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:class:`.Connectable` must be present in the
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``.bind`` property.
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:param target:
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Optional, defaults to None. The target SchemaItem for the
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execute call. Will be passed to the ``on`` callable if any,
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and may also provide string expansion data for the
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statement. See ``execute_at`` for more information.
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"""
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if bind is None:
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bind = _bind_or_error(self)
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if self._should_execute(target, bind):
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return bind.execute(self.against(target))
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else:
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bind.engine.logger.info(
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"DDL execution skipped, criteria not met.")
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@util.deprecated("0.7", "See :class:`.DDLEvents`, as well as "
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":meth:`.DDLElement.execute_if`.")
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def execute_at(self, event_name, target):
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"""Link execution of this DDL to the DDL lifecycle of a SchemaItem.
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Links this ``DDLElement`` to a ``Table`` or ``MetaData`` instance,
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executing it when that schema item is created or dropped. The DDL
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statement will be executed using the same Connection and transactional
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context as the Table create/drop itself. The ``.bind`` property of
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this statement is ignored.
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:param event:
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One of the events defined in the schema item's ``.ddl_events``;
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e.g. 'before-create', 'after-create', 'before-drop' or 'after-drop'
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:param target:
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The Table or MetaData instance for which this DDLElement will
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be associated with.
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A DDLElement instance can be linked to any number of schema items.
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``execute_at`` builds on the ``append_ddl_listener`` interface of
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:class:`.MetaData` and :class:`.Table` objects.
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Caveat: Creating or dropping a Table in isolation will also trigger
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any DDL set to ``execute_at`` that Table's MetaData. This may change
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in a future release.
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"""
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def call_event(target, connection, **kw):
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if self._should_execute_deprecated(event_name,
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target, connection, **kw):
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return connection.execute(self.against(target))
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event.listen(target, "" + event_name.replace('-', '_'), call_event)
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@_generative
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def against(self, target):
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"""Return a copy of this DDL against a specific schema item."""
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self.target = target
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@_generative
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def execute_if(self, dialect=None, callable_=None, state=None):
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"""Return a callable that will execute this
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DDLElement conditionally.
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Used to provide a wrapper for event listening::
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event.listen(
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metadata,
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'before_create',
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DDL("my_ddl").execute_if(dialect='postgresql')
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)
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:param dialect: May be a string, tuple or a callable
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predicate. If a string, it will be compared to the name of the
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executing database dialect::
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DDL('something').execute_if(dialect='postgresql')
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If a tuple, specifies multiple dialect names::
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DDL('something').execute_if(dialect=('postgresql', 'mysql'))
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:param callable_: A callable, which will be invoked with
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four positional arguments as well as optional keyword
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arguments:
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:ddl:
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This DDL element.
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:target:
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The :class:`.Table` or :class:`.MetaData` object which is the
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target of this event. May be None if the DDL is executed
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explicitly.
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:bind:
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The :class:`.Connection` being used for DDL execution
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:tables:
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Optional keyword argument - a list of Table objects which are to
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be created/ dropped within a MetaData.create_all() or drop_all()
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method call.
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:state:
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Optional keyword argument - will be the ``state`` argument
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passed to this function.
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:checkfirst:
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Keyword argument, will be True if the 'checkfirst' flag was
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set during the call to ``create()``, ``create_all()``,
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``drop()``, ``drop_all()``.
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If the callable returns a true value, the DDL statement will be
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executed.
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:param state: any value which will be passed to the callable\_
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as the ``state`` keyword argument.
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.. seealso::
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:class:`.DDLEvents`
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:ref:`event_toplevel`
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"""
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self.dialect = dialect
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self.callable_ = callable_
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self.state = state
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def _should_execute(self, target, bind, **kw):
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if self.on is not None and \
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not self._should_execute_deprecated(None, target, bind, **kw):
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return False
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if isinstance(self.dialect, util.string_types):
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if self.dialect != bind.engine.name:
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return False
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elif isinstance(self.dialect, (tuple, list, set)):
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if bind.engine.name not in self.dialect:
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return False
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if (self.callable_ is not None and
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not self.callable_(self, target, bind,
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state=self.state, **kw)):
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return False
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return True
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def _should_execute_deprecated(self, event, target, bind, **kw):
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if self.on is None:
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return True
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elif isinstance(self.on, util.string_types):
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return self.on == bind.engine.name
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elif isinstance(self.on, (tuple, list, set)):
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return bind.engine.name in self.on
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else:
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return self.on(self, event, target, bind, **kw)
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def __call__(self, target, bind, **kw):
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"""Execute the DDL as a ddl_listener."""
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if self._should_execute(target, bind, **kw):
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return bind.execute(self.against(target))
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def _check_ddl_on(self, on):
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if (on is not None and
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(not isinstance(on, util.string_types + (tuple, list, set)) and
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not util.callable(on))):
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raise exc.ArgumentError(
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"Expected the name of a database dialect, a tuple "
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"of names, or a callable for "
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"'on' criteria, got type '%s'." % type(on).__name__)
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def bind(self):
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if self._bind:
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return self._bind
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def _set_bind(self, bind):
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self._bind = bind
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bind = property(bind, _set_bind)
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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 DDL(DDLElement):
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"""A literal DDL statement.
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Specifies literal SQL DDL to be executed by the database. DDL objects
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function as DDL event listeners, and can be subscribed to those events
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listed in :class:`.DDLEvents`, using either :class:`.Table` or
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:class:`.MetaData` objects as targets. Basic templating support allows
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a single DDL instance to handle repetitive tasks for multiple tables.
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Examples::
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from sqlalchemy import event, DDL
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tbl = Table('users', metadata, Column('uid', Integer))
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event.listen(tbl, 'before_create', DDL('DROP TRIGGER users_trigger'))
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spow = DDL('ALTER TABLE %(table)s SET secretpowers TRUE')
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event.listen(tbl, 'after_create', spow.execute_if(dialect='somedb'))
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drop_spow = DDL('ALTER TABLE users SET secretpowers FALSE')
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connection.execute(drop_spow)
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When operating on Table events, the following ``statement``
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string substitions are available::
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%(table)s - the Table name, with any required quoting applied
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%(schema)s - the schema name, with any required quoting applied
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%(fullname)s - the Table name including schema, quoted if needed
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The DDL's "context", if any, will be combined with the standard
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substitutions noted above. Keys present in the context will override
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the standard substitutions.
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"""
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__visit_name__ = "ddl"
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def __init__(self, statement, on=None, context=None, bind=None):
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"""Create a DDL statement.
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:param statement:
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A string or unicode string to be executed. Statements will be
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processed with Python's string formatting operator. See the
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``context`` argument and the ``execute_at`` method.
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A literal '%' in a statement must be escaped as '%%'.
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SQL bind parameters are not available in DDL statements.
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:param on:
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.. deprecated:: 0.7
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See :meth:`.DDLElement.execute_if`.
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Optional filtering criteria. May be a string, tuple or a callable
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predicate. If a string, it will be compared to the name of the
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executing database dialect::
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DDL('something', on='postgresql')
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If a tuple, specifies multiple dialect names::
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DDL('something', on=('postgresql', 'mysql'))
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If a callable, it will be invoked with four positional arguments
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as well as optional keyword arguments:
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:ddl:
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This DDL element.
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:event:
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The name of the event that has triggered this DDL, such as
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'after-create' Will be None if the DDL is executed explicitly.
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:target:
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The ``Table`` or ``MetaData`` object which is the target of
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this event. May be None if the DDL is executed explicitly.
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:connection:
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The ``Connection`` being used for DDL execution
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:tables:
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Optional keyword argument - a list of Table objects which are to
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be created/ dropped within a MetaData.create_all() or drop_all()
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method call.
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If the callable returns a true value, the DDL statement will be
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executed.
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:param context:
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Optional dictionary, defaults to None. These values will be
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available for use in string substitutions on the DDL statement.
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:param bind:
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Optional. A :class:`.Connectable`, used by
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default when ``execute()`` is invoked without a bind argument.
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.. seealso::
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:class:`.DDLEvents`
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:ref:`event_toplevel`
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"""
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if not isinstance(statement, util.string_types):
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raise exc.ArgumentError(
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"Expected a string or unicode SQL statement, got '%r'" %
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statement)
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self.statement = statement
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self.context = context or {}
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self._check_ddl_on(on)
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self.on = on
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self._bind = bind
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def __repr__(self):
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return '<%s@%s; %s>' % (
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type(self).__name__, id(self),
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', '.join([repr(self.statement)] +
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['%s=%r' % (key, getattr(self, key))
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for key in ('on', 'context')
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if getattr(self, key)]))
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class _CreateDropBase(DDLElement):
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"""Base class for DDL constructs that represent CREATE and DROP or
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equivalents.
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The common theme of _CreateDropBase is a single
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``element`` attribute which refers to the element
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to be created or dropped.
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"""
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def __init__(self, element, on=None, bind=None):
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self.element = element
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self._check_ddl_on(on)
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self.on = on
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self.bind = bind
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def _create_rule_disable(self, compiler):
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"""Allow disable of _create_rule using a callable.
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Pass to _create_rule using
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util.portable_instancemethod(self._create_rule_disable)
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to retain serializability.
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"""
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return False
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class CreateSchema(_CreateDropBase):
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"""Represent a CREATE SCHEMA statement.
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.. versionadded:: 0.7.4
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The argument here is the string name of the schema.
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"""
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__visit_name__ = "create_schema"
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def __init__(self, name, quote=None, **kw):
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"""Create a new :class:`.CreateSchema` construct."""
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self.quote = quote
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super(CreateSchema, self).__init__(name, **kw)
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class DropSchema(_CreateDropBase):
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"""Represent a DROP SCHEMA statement.
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The argument here is the string name of the schema.
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.. versionadded:: 0.7.4
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"""
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__visit_name__ = "drop_schema"
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def __init__(self, name, quote=None, cascade=False, **kw):
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"""Create a new :class:`.DropSchema` construct."""
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self.quote = quote
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self.cascade = cascade
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super(DropSchema, self).__init__(name, **kw)
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class CreateTable(_CreateDropBase):
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"""Represent a CREATE TABLE statement."""
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__visit_name__ = "create_table"
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def __init__(
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self, element, on=None, bind=None,
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include_foreign_key_constraints=None):
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"""Create a :class:`.CreateTable` construct.
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:param element: a :class:`.Table` that's the subject
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of the CREATE
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:param on: See the description for 'on' in :class:`.DDL`.
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:param bind: See the description for 'bind' in :class:`.DDL`.
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:param include_foreign_key_constraints: optional sequence of
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:class:`.ForeignKeyConstraint` objects that will be included
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inline within the CREATE construct; if omitted, all foreign key
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constraints that do not specify use_alter=True are included.
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.. versionadded:: 1.0.0
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"""
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super(CreateTable, self).__init__(element, on=on, bind=bind)
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self.columns = [CreateColumn(column)
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for column in element.columns
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]
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self.include_foreign_key_constraints = include_foreign_key_constraints
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class _DropView(_CreateDropBase):
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"""Semi-public 'DROP VIEW' construct.
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Used by the test suite for dialect-agnostic drops of views.
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This object will eventually be part of a public "view" API.
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"""
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__visit_name__ = "drop_view"
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class CreateColumn(_DDLCompiles):
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"""Represent a :class:`.Column` as rendered in a CREATE TABLE statement,
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via the :class:`.CreateTable` construct.
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This is provided to support custom column DDL within the generation
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of CREATE TABLE statements, by using the
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compiler extension documented in :ref:`sqlalchemy.ext.compiler_toplevel`
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to extend :class:`.CreateColumn`.
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Typical integration is to examine the incoming :class:`.Column`
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object, and to redirect compilation if a particular flag or condition
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is found::
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from sqlalchemy import schema
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from sqlalchemy.ext.compiler import compiles
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@compiles(schema.CreateColumn)
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def compile(element, compiler, **kw):
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column = element.element
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if "special" not in column.info:
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return compiler.visit_create_column(element, **kw)
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text = "%s SPECIAL DIRECTIVE %s" % (
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column.name,
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compiler.type_compiler.process(column.type)
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)
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default = compiler.get_column_default_string(column)
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if default is not None:
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text += " DEFAULT " + default
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if not column.nullable:
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text += " NOT NULL"
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if column.constraints:
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text += " ".join(
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compiler.process(const)
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for const in column.constraints)
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return text
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|
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The above construct can be applied to a :class:`.Table` as follows::
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from sqlalchemy import Table, Metadata, Column, Integer, String
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from sqlalchemy import schema
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metadata = MetaData()
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table = Table('mytable', MetaData(),
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Column('x', Integer, info={"special":True}, primary_key=True),
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Column('y', String(50)),
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Column('z', String(20), info={"special":True})
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)
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metadata.create_all(conn)
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Above, the directives we've added to the :attr:`.Column.info` collection
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will be detected by our custom compilation scheme::
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CREATE TABLE mytable (
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x SPECIAL DIRECTIVE INTEGER NOT NULL,
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y VARCHAR(50),
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z SPECIAL DIRECTIVE VARCHAR(20),
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PRIMARY KEY (x)
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)
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The :class:`.CreateColumn` construct can also be used to skip certain
|
|
columns when producing a ``CREATE TABLE``. This is accomplished by
|
|
creating a compilation rule that conditionally returns ``None``.
|
|
This is essentially how to produce the same effect as using the
|
|
``system=True`` argument on :class:`.Column`, which marks a column
|
|
as an implicitly-present "system" column.
|
|
|
|
For example, suppose we wish to produce a :class:`.Table` which skips
|
|
rendering of the Postgresql ``xmin`` column against the Postgresql
|
|
backend, but on other backends does render it, in anticipation of a
|
|
triggered rule. A conditional compilation rule could skip this name only
|
|
on Postgresql::
|
|
|
|
from sqlalchemy.schema import CreateColumn
|
|
|
|
@compiles(CreateColumn, "postgresql")
|
|
def skip_xmin(element, compiler, **kw):
|
|
if element.element.name == 'xmin':
|
|
return None
|
|
else:
|
|
return compiler.visit_create_column(element, **kw)
|
|
|
|
|
|
my_table = Table('mytable', metadata,
|
|
Column('id', Integer, primary_key=True),
|
|
Column('xmin', Integer)
|
|
)
|
|
|
|
Above, a :class:`.CreateTable` construct will generate a ``CREATE TABLE``
|
|
which only includes the ``id`` column in the string; the ``xmin`` column
|
|
will be omitted, but only against the Postgresql backend.
|
|
|
|
.. versionadded:: 0.8.3 The :class:`.CreateColumn` construct supports
|
|
skipping of columns by returning ``None`` from a custom compilation
|
|
rule.
|
|
|
|
.. versionadded:: 0.8 The :class:`.CreateColumn` construct was added
|
|
to support custom column creation styles.
|
|
|
|
"""
|
|
__visit_name__ = 'create_column'
|
|
|
|
def __init__(self, element):
|
|
self.element = element
|
|
|
|
|
|
class DropTable(_CreateDropBase):
|
|
"""Represent a DROP TABLE statement."""
|
|
|
|
__visit_name__ = "drop_table"
|
|
|
|
|
|
class CreateSequence(_CreateDropBase):
|
|
"""Represent a CREATE SEQUENCE statement."""
|
|
|
|
__visit_name__ = "create_sequence"
|
|
|
|
|
|
class DropSequence(_CreateDropBase):
|
|
"""Represent a DROP SEQUENCE statement."""
|
|
|
|
__visit_name__ = "drop_sequence"
|
|
|
|
|
|
class CreateIndex(_CreateDropBase):
|
|
"""Represent a CREATE INDEX statement."""
|
|
|
|
__visit_name__ = "create_index"
|
|
|
|
|
|
class DropIndex(_CreateDropBase):
|
|
"""Represent a DROP INDEX statement."""
|
|
|
|
__visit_name__ = "drop_index"
|
|
|
|
|
|
class AddConstraint(_CreateDropBase):
|
|
"""Represent an ALTER TABLE ADD CONSTRAINT statement."""
|
|
|
|
__visit_name__ = "add_constraint"
|
|
|
|
def __init__(self, element, *args, **kw):
|
|
super(AddConstraint, self).__init__(element, *args, **kw)
|
|
element._create_rule = util.portable_instancemethod(
|
|
self._create_rule_disable)
|
|
|
|
|
|
class DropConstraint(_CreateDropBase):
|
|
"""Represent an ALTER TABLE DROP CONSTRAINT statement."""
|
|
|
|
__visit_name__ = "drop_constraint"
|
|
|
|
def __init__(self, element, cascade=False, **kw):
|
|
self.cascade = cascade
|
|
super(DropConstraint, self).__init__(element, **kw)
|
|
element._create_rule = util.portable_instancemethod(
|
|
self._create_rule_disable)
|
|
|
|
|
|
class DDLBase(SchemaVisitor):
|
|
def __init__(self, connection):
|
|
self.connection = connection
|
|
|
|
|
|
class SchemaGenerator(DDLBase):
|
|
|
|
def __init__(self, dialect, connection, checkfirst=False,
|
|
tables=None, **kwargs):
|
|
super(SchemaGenerator, self).__init__(connection, **kwargs)
|
|
self.checkfirst = checkfirst
|
|
self.tables = tables
|
|
self.preparer = dialect.identifier_preparer
|
|
self.dialect = dialect
|
|
self.memo = {}
|
|
|
|
def _can_create_table(self, table):
|
|
self.dialect.validate_identifier(table.name)
|
|
if table.schema:
|
|
self.dialect.validate_identifier(table.schema)
|
|
return not self.checkfirst or \
|
|
not self.dialect.has_table(self.connection,
|
|
table.name, schema=table.schema)
|
|
|
|
def _can_create_sequence(self, sequence):
|
|
return self.dialect.supports_sequences and \
|
|
(
|
|
(not self.dialect.sequences_optional or
|
|
not sequence.optional) and
|
|
(
|
|
not self.checkfirst or
|
|
not self.dialect.has_sequence(
|
|
self.connection,
|
|
sequence.name,
|
|
schema=sequence.schema)
|
|
)
|
|
)
|
|
|
|
def visit_metadata(self, metadata):
|
|
if self.tables is not None:
|
|
tables = self.tables
|
|
else:
|
|
tables = list(metadata.tables.values())
|
|
|
|
collection = sort_tables_and_constraints(
|
|
[t for t in tables if self._can_create_table(t)])
|
|
|
|
seq_coll = [s for s in metadata._sequences.values()
|
|
if s.column is None and self._can_create_sequence(s)]
|
|
|
|
event_collection = [
|
|
t for (t, fks) in collection if t is not None
|
|
]
|
|
metadata.dispatch.before_create(metadata, self.connection,
|
|
tables=event_collection,
|
|
checkfirst=self.checkfirst,
|
|
_ddl_runner=self)
|
|
|
|
for seq in seq_coll:
|
|
self.traverse_single(seq, create_ok=True)
|
|
|
|
for table, fkcs in collection:
|
|
if table is not None:
|
|
self.traverse_single(
|
|
table, create_ok=True,
|
|
include_foreign_key_constraints=fkcs,
|
|
_is_metadata_operation=True)
|
|
else:
|
|
for fkc in fkcs:
|
|
self.traverse_single(fkc)
|
|
|
|
metadata.dispatch.after_create(metadata, self.connection,
|
|
tables=event_collection,
|
|
checkfirst=self.checkfirst,
|
|
_ddl_runner=self)
|
|
|
|
def visit_table(
|
|
self, table, create_ok=False,
|
|
include_foreign_key_constraints=None,
|
|
_is_metadata_operation=False):
|
|
if not create_ok and not self._can_create_table(table):
|
|
return
|
|
|
|
table.dispatch.before_create(
|
|
table, self.connection,
|
|
checkfirst=self.checkfirst,
|
|
_ddl_runner=self,
|
|
_is_metadata_operation=_is_metadata_operation)
|
|
|
|
for column in table.columns:
|
|
if column.default is not None:
|
|
self.traverse_single(column.default)
|
|
|
|
if not self.dialect.supports_alter:
|
|
# e.g., don't omit any foreign key constraints
|
|
include_foreign_key_constraints = None
|
|
|
|
self.connection.execute(
|
|
CreateTable(
|
|
table,
|
|
include_foreign_key_constraints=include_foreign_key_constraints
|
|
))
|
|
|
|
if hasattr(table, 'indexes'):
|
|
for index in table.indexes:
|
|
self.traverse_single(index)
|
|
|
|
table.dispatch.after_create(
|
|
table, self.connection,
|
|
checkfirst=self.checkfirst,
|
|
_ddl_runner=self,
|
|
_is_metadata_operation=_is_metadata_operation)
|
|
|
|
def visit_foreign_key_constraint(self, constraint):
|
|
if not self.dialect.supports_alter:
|
|
return
|
|
self.connection.execute(AddConstraint(constraint))
|
|
|
|
def visit_sequence(self, sequence, create_ok=False):
|
|
if not create_ok and not self._can_create_sequence(sequence):
|
|
return
|
|
self.connection.execute(CreateSequence(sequence))
|
|
|
|
def visit_index(self, index):
|
|
self.connection.execute(CreateIndex(index))
|
|
|
|
|
|
class SchemaDropper(DDLBase):
|
|
|
|
def __init__(self, dialect, connection, checkfirst=False,
|
|
tables=None, **kwargs):
|
|
super(SchemaDropper, self).__init__(connection, **kwargs)
|
|
self.checkfirst = checkfirst
|
|
self.tables = tables
|
|
self.preparer = dialect.identifier_preparer
|
|
self.dialect = dialect
|
|
self.memo = {}
|
|
|
|
def visit_metadata(self, metadata):
|
|
if self.tables is not None:
|
|
tables = self.tables
|
|
else:
|
|
tables = list(metadata.tables.values())
|
|
|
|
try:
|
|
unsorted_tables = [t for t in tables if self._can_drop_table(t)]
|
|
collection = list(reversed(
|
|
sort_tables_and_constraints(
|
|
unsorted_tables,
|
|
filter_fn=lambda constraint: False
|
|
if not self.dialect.supports_alter
|
|
or constraint.name is None
|
|
else None
|
|
)
|
|
))
|
|
except exc.CircularDependencyError as err2:
|
|
if not self.dialect.supports_alter:
|
|
util.warn(
|
|
"Can't sort tables for DROP; an "
|
|
"unresolvable foreign key "
|
|
"dependency exists between tables: %s, and backend does "
|
|
"not support ALTER. To restore at least a partial sort, "
|
|
"apply use_alter=True to ForeignKey and "
|
|
"ForeignKeyConstraint "
|
|
"objects involved in the cycle to mark these as known "
|
|
"cycles that will be ignored."
|
|
% (
|
|
", ".join(sorted([t.fullname for t in err2.cycles]))
|
|
)
|
|
)
|
|
collection = [(t, ()) for t in unsorted_tables]
|
|
else:
|
|
util.raise_from_cause(
|
|
exc.CircularDependencyError(
|
|
err2.args[0],
|
|
err2.cycles, err2.edges,
|
|
msg="Can't sort tables for DROP; an "
|
|
"unresolvable foreign key "
|
|
"dependency exists between tables: %s. Please ensure "
|
|
"that the ForeignKey and ForeignKeyConstraint objects "
|
|
"involved in the cycle have "
|
|
"names so that they can be dropped using "
|
|
"DROP CONSTRAINT."
|
|
% (
|
|
", ".join(sorted([t.fullname for t in err2.cycles]))
|
|
)
|
|
|
|
)
|
|
)
|
|
|
|
seq_coll = [
|
|
s
|
|
for s in metadata._sequences.values()
|
|
if s.column is None and self._can_drop_sequence(s)
|
|
]
|
|
|
|
event_collection = [
|
|
t for (t, fks) in collection if t is not None
|
|
]
|
|
|
|
metadata.dispatch.before_drop(
|
|
metadata, self.connection, tables=event_collection,
|
|
checkfirst=self.checkfirst, _ddl_runner=self)
|
|
|
|
for table, fkcs in collection:
|
|
if table is not None:
|
|
self.traverse_single(
|
|
table, drop_ok=True, _is_metadata_operation=True)
|
|
else:
|
|
for fkc in fkcs:
|
|
self.traverse_single(fkc)
|
|
|
|
for seq in seq_coll:
|
|
self.traverse_single(seq, drop_ok=True)
|
|
|
|
metadata.dispatch.after_drop(
|
|
metadata, self.connection, tables=event_collection,
|
|
checkfirst=self.checkfirst, _ddl_runner=self)
|
|
|
|
def _can_drop_table(self, table):
|
|
self.dialect.validate_identifier(table.name)
|
|
if table.schema:
|
|
self.dialect.validate_identifier(table.schema)
|
|
return not self.checkfirst or self.dialect.has_table(
|
|
self.connection, table.name, schema=table.schema)
|
|
|
|
def _can_drop_sequence(self, sequence):
|
|
return self.dialect.supports_sequences and \
|
|
((not self.dialect.sequences_optional or
|
|
not sequence.optional) and
|
|
(not self.checkfirst or
|
|
self.dialect.has_sequence(
|
|
self.connection,
|
|
sequence.name,
|
|
schema=sequence.schema))
|
|
)
|
|
|
|
def visit_index(self, index):
|
|
self.connection.execute(DropIndex(index))
|
|
|
|
def visit_table(self, table, drop_ok=False, _is_metadata_operation=False):
|
|
if not drop_ok and not self._can_drop_table(table):
|
|
return
|
|
|
|
table.dispatch.before_drop(
|
|
table, self.connection,
|
|
checkfirst=self.checkfirst,
|
|
_ddl_runner=self,
|
|
_is_metadata_operation=_is_metadata_operation)
|
|
|
|
for column in table.columns:
|
|
if column.default is not None:
|
|
self.traverse_single(column.default)
|
|
|
|
self.connection.execute(DropTable(table))
|
|
|
|
table.dispatch.after_drop(
|
|
table, self.connection,
|
|
checkfirst=self.checkfirst,
|
|
_ddl_runner=self,
|
|
_is_metadata_operation=_is_metadata_operation)
|
|
|
|
def visit_foreign_key_constraint(self, constraint):
|
|
if not self.dialect.supports_alter:
|
|
return
|
|
self.connection.execute(DropConstraint(constraint))
|
|
|
|
def visit_sequence(self, sequence, drop_ok=False):
|
|
if not drop_ok and not self._can_drop_sequence(sequence):
|
|
return
|
|
self.connection.execute(DropSequence(sequence))
|
|
|
|
|
|
def sort_tables(tables, skip_fn=None, extra_dependencies=None):
|
|
"""sort a collection of :class:`.Table` objects based on dependency.
|
|
|
|
This is a dependency-ordered sort which will emit :class:`.Table`
|
|
objects such that they will follow their dependent :class:`.Table` objects.
|
|
Tables are dependent on another based on the presence of
|
|
:class:`.ForeignKeyConstraint` objects as well as explicit dependencies
|
|
added by :meth:`.Table.add_is_dependent_on`.
|
|
|
|
.. warning::
|
|
|
|
The :func:`.sort_tables` function cannot by itself accommodate
|
|
automatic resolution of dependency cycles between tables, which
|
|
are usually caused by mutually dependent foreign key constraints.
|
|
To resolve these cycles, either the
|
|
:paramref:`.ForeignKeyConstraint.use_alter` parameter may be appled
|
|
to those constraints, or use the
|
|
:func:`.sql.sort_tables_and_constraints` function which will break
|
|
out foreign key constraints involved in cycles separately.
|
|
|
|
:param tables: a sequence of :class:`.Table` objects.
|
|
|
|
:param skip_fn: optional callable which will be passed a
|
|
:class:`.ForeignKey` object; if it returns True, this
|
|
constraint will not be considered as a dependency. Note this is
|
|
**different** from the same parameter in
|
|
:func:`.sort_tables_and_constraints`, which is
|
|
instead passed the owning :class:`.ForeignKeyConstraint` object.
|
|
|
|
:param extra_dependencies: a sequence of 2-tuples of tables which will
|
|
also be considered as dependent on each other.
|
|
|
|
.. seealso::
|
|
|
|
:func:`.sort_tables_and_constraints`
|
|
|
|
:meth:`.MetaData.sorted_tables` - uses this function to sort
|
|
|
|
|
|
"""
|
|
|
|
if skip_fn is not None:
|
|
def _skip_fn(fkc):
|
|
for fk in fkc.elements:
|
|
if skip_fn(fk):
|
|
return True
|
|
else:
|
|
return None
|
|
else:
|
|
_skip_fn = None
|
|
|
|
return [
|
|
t for (t, fkcs) in
|
|
sort_tables_and_constraints(
|
|
tables, filter_fn=_skip_fn, extra_dependencies=extra_dependencies)
|
|
if t is not None
|
|
]
|
|
|
|
|
|
def sort_tables_and_constraints(
|
|
tables, filter_fn=None, extra_dependencies=None):
|
|
"""sort a collection of :class:`.Table` / :class:`.ForeignKeyConstraint`
|
|
objects.
|
|
|
|
This is a dependency-ordered sort which will emit tuples of
|
|
``(Table, [ForeignKeyConstraint, ...])`` such that each
|
|
:class:`.Table` follows its dependent :class:`.Table` objects.
|
|
Remaining :class:`.ForeignKeyConstraint` objects that are separate due to
|
|
dependency rules not satisifed by the sort are emitted afterwards
|
|
as ``(None, [ForeignKeyConstraint ...])``.
|
|
|
|
Tables are dependent on another based on the presence of
|
|
:class:`.ForeignKeyConstraint` objects, explicit dependencies
|
|
added by :meth:`.Table.add_is_dependent_on`, as well as dependencies
|
|
stated here using the :paramref:`~.sort_tables_and_constraints.skip_fn`
|
|
and/or :paramref:`~.sort_tables_and_constraints.extra_dependencies`
|
|
parameters.
|
|
|
|
:param tables: a sequence of :class:`.Table` objects.
|
|
|
|
:param filter_fn: optional callable which will be passed a
|
|
:class:`.ForeignKeyConstraint` object, and returns a value based on
|
|
whether this constraint should definitely be included or excluded as
|
|
an inline constraint, or neither. If it returns False, the constraint
|
|
will definitely be included as a dependency that cannot be subject
|
|
to ALTER; if True, it will **only** be included as an ALTER result at
|
|
the end. Returning None means the constraint is included in the
|
|
table-based result unless it is detected as part of a dependency cycle.
|
|
|
|
:param extra_dependencies: a sequence of 2-tuples of tables which will
|
|
also be considered as dependent on each other.
|
|
|
|
.. versionadded:: 1.0.0
|
|
|
|
.. seealso::
|
|
|
|
:func:`.sort_tables`
|
|
|
|
|
|
"""
|
|
|
|
fixed_dependencies = set()
|
|
mutable_dependencies = set()
|
|
|
|
if extra_dependencies is not None:
|
|
fixed_dependencies.update(extra_dependencies)
|
|
|
|
remaining_fkcs = set()
|
|
for table in tables:
|
|
for fkc in table.foreign_key_constraints:
|
|
if fkc.use_alter is True:
|
|
remaining_fkcs.add(fkc)
|
|
continue
|
|
|
|
if filter_fn:
|
|
filtered = filter_fn(fkc)
|
|
|
|
if filtered is True:
|
|
remaining_fkcs.add(fkc)
|
|
continue
|
|
|
|
dependent_on = fkc.referred_table
|
|
if dependent_on is not table:
|
|
mutable_dependencies.add((dependent_on, table))
|
|
|
|
fixed_dependencies.update(
|
|
(parent, table) for parent in table._extra_dependencies
|
|
)
|
|
|
|
try:
|
|
candidate_sort = list(
|
|
topological.sort(
|
|
fixed_dependencies.union(mutable_dependencies), tables,
|
|
deterministic_order=True
|
|
)
|
|
)
|
|
except exc.CircularDependencyError as err:
|
|
for edge in err.edges:
|
|
if edge in mutable_dependencies:
|
|
table = edge[1]
|
|
can_remove = [
|
|
fkc for fkc in table.foreign_key_constraints
|
|
if filter_fn is None or filter_fn(fkc) is not False]
|
|
remaining_fkcs.update(can_remove)
|
|
for fkc in can_remove:
|
|
dependent_on = fkc.referred_table
|
|
if dependent_on is not table:
|
|
mutable_dependencies.discard((dependent_on, table))
|
|
candidate_sort = list(
|
|
topological.sort(
|
|
fixed_dependencies.union(mutable_dependencies), tables,
|
|
deterministic_order=True
|
|
)
|
|
)
|
|
|
|
return [
|
|
(table, table.foreign_key_constraints.difference(remaining_fkcs))
|
|
for table in candidate_sort
|
|
] + [(None, list(remaining_fkcs))]
|