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# sql/selectable.py
# Copyright (C) 2005-2020 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""The :class:`_expression.FromClause` class of SQL expression elements,
representing
SQL tables and derived rowsets.
"""
import collections
import itertools
from operator import attrgetter
from . import coercions
from . import operators
from . import roles
from . import type_api
from .annotation import Annotated
from .annotation import SupportsCloneAnnotations
from .base import _clone
from .base import _cloned_difference
from .base import _cloned_intersection
from .base import _entity_namespace_key
from .base import _expand_cloned
from .base import _from_objects
from .base import _generative
from .base import _select_iterables
from .base import CacheableOptions
from .base import ColumnCollection
from .base import ColumnSet
from .base import CompileState
from .base import DedupeColumnCollection
from .base import Executable
from .base import Generative
from .base import HasCompileState
from .base import HasMemoized
from .base import Immutable
from .base import prefix_anon_map
from .coercions import _document_text_coercion
from .elements import _anonymous_label
from .elements import and_
from .elements import BindParameter
from .elements import BooleanClauseList
from .elements import ClauseElement
from .elements import ClauseList
from .elements import ColumnClause
from .elements import GroupedElement
from .elements import Grouping
from .elements import literal_column
from .elements import UnaryExpression
from .visitors import InternalTraversal
from .. import exc
from .. import util
if util.TYPE_CHECKING:
from typing import Any
from typing import Optional
class _OffsetLimitParam(BindParameter):
inherit_cache = True
@property
def _limit_offset_value(self):
return self.effective_value
@util.deprecated(
"1.4",
"The standalone :func:`.subquery` function is deprecated "
"and will be removed in a future release. Use select().subquery().",
)
def subquery(alias, *args, **kwargs):
r"""Return an :class:`.Subquery` object derived
from a :class:`_expression.Select`.
:param alias: the alias name for the subquery
:param \*args, \**kwargs: all other arguments are passed through to the
:func:`_expression.select` function.
"""
return Select.create_legacy_select(*args, **kwargs).subquery(alias)
class ReturnsRows(roles.ReturnsRowsRole, ClauseElement):
"""The basemost class for Core constructs that have some concept of
columns that can represent rows.
While the SELECT statement and TABLE are the primary things we think
of in this category, DML like INSERT, UPDATE and DELETE can also specify
RETURNING which means they can be used in CTEs and other forms, and
PostgreSQL has functions that return rows also.
.. versionadded:: 1.4
"""
_is_returns_rows = True
# sub-elements of returns_rows
_is_from_clause = False
_is_select_statement = False
_is_lateral = False
@property
def selectable(self):
raise NotImplementedError()
def _exported_columns_iterator(self):
"""An iterator of column objects that represents the "exported"
columns of this :class:`_expression.ReturnsRows`.
This is the same set of columns as are returned by
:meth:`_expression.ReturnsRows.exported_columns`
except they are returned
as a simple iterator or sequence, rather than as a
:class:`_expression.ColumnCollection` namespace.
Subclasses should re-implement this method to bypass the interim
creation of the :class:`_expression.ColumnCollection` if appropriate.
"""
return iter(self.exported_columns)
@property
def exported_columns(self):
"""A :class:`_expression.ColumnCollection`
that represents the "exported"
columns of this :class:`_expression.ReturnsRows`.
The "exported" columns represent the collection of
:class:`_expression.ColumnElement`
expressions that are rendered by this SQL
construct. There are primary varieties which are the
"FROM clause columns" of a FROM clause, such as a table, join,
or subquery, the "SELECTed columns", which are the columns in
the "columns clause" of a SELECT statement, and the RETURNING
columns in a DML statement..
.. versionadded:: 1.4
.. seealso::
:attr:`_expression.FromClause.exported_columns`
:attr:`_expression.SelectBase.exported_columns`
"""
raise NotImplementedError()
class Selectable(ReturnsRows):
"""Mark a class as being selectable.
"""
__visit_name__ = "selectable"
is_selectable = True
@property
def selectable(self):
return self
def _refresh_for_new_column(self, column):
raise NotImplementedError()
def lateral(self, name=None):
"""Return a LATERAL alias of this :class:`_expression.Selectable`.
The return value is the :class:`_expression.Lateral` construct also
provided by the top-level :func:`_expression.lateral` function.
.. versionadded:: 1.1
.. seealso::
:ref:`lateral_selects` - overview of usage.
"""
return Lateral._construct(self, name)
@util.deprecated(
"1.4",
message="The :meth:`.Selectable.replace_selectable` method is "
"deprecated, and will be removed in a future release. Similar "
"functionality is available via the sqlalchemy.sql.visitors module.",
)
@util.preload_module("sqlalchemy.sql.util")
def replace_selectable(self, old, alias):
"""Replace all occurrences of :class:`_expression.FromClause`
'old' with the given :class:`_expression.Alias`
object, returning a copy of this :class:`_expression.FromClause`.
"""
return util.preloaded.sql_util.ClauseAdapter(alias).traverse(self)
def corresponding_column(self, column, require_embedded=False):
"""Given a :class:`_expression.ColumnElement`, return the exported
:class:`_expression.ColumnElement` object from the
:attr:`_expression.Selectable.exported_columns`
collection of this :class:`_expression.Selectable`
which corresponds to that
original :class:`_expression.ColumnElement` via a common ancestor
column.
:param column: the target :class:`_expression.ColumnElement`
to be matched.
:param require_embedded: only return corresponding columns for
the given :class:`_expression.ColumnElement`, if the given
:class:`_expression.ColumnElement`
is actually present within a sub-element
of this :class:`_expression.Selectable`.
Normally the column will match if
it merely shares a common ancestor with one of the exported
columns of this :class:`_expression.Selectable`.
.. seealso::
:attr:`_expression.Selectable.exported_columns` - the
:class:`_expression.ColumnCollection`
that is used for the operation.
:meth:`_expression.ColumnCollection.corresponding_column`
- implementation
method.
"""
return self.exported_columns.corresponding_column(
column, require_embedded
)
class HasPrefixes(object):
_prefixes = ()
_has_prefixes_traverse_internals = [
("_prefixes", InternalTraversal.dp_prefix_sequence)
]
@_generative
@_document_text_coercion(
"expr",
":meth:`_expression.HasPrefixes.prefix_with`",
":paramref:`.HasPrefixes.prefix_with.*expr`",
)
def prefix_with(self, *expr, **kw):
r"""Add one or more expressions following the statement keyword, i.e.
SELECT, INSERT, UPDATE, or DELETE. Generative.
This is used to support backend-specific prefix keywords such as those
provided by MySQL.
E.g.::
stmt = table.insert().prefix_with("LOW_PRIORITY", dialect="mysql")
# MySQL 5.7 optimizer hints
stmt = select([table]).prefix_with(
"/*+ BKA(t1) */", dialect="mysql")
Multiple prefixes can be specified by multiple calls
to :meth:`_expression.HasPrefixes.prefix_with`.
:param \*expr: textual or :class:`_expression.ClauseElement`
construct which
will be rendered following the INSERT, UPDATE, or DELETE
keyword.
:param \**kw: A single keyword 'dialect' is accepted. This is an
optional string dialect name which will
limit rendering of this prefix to only that dialect.
"""
dialect = kw.pop("dialect", None)
if kw:
raise exc.ArgumentError(
"Unsupported argument(s): %s" % ",".join(kw)
)
self._setup_prefixes(expr, dialect)
def _setup_prefixes(self, prefixes, dialect=None):
self._prefixes = self._prefixes + tuple(
[
(coercions.expect(roles.StatementOptionRole, p), dialect)
for p in prefixes
]
)
class HasSuffixes(object):
_suffixes = ()
_has_suffixes_traverse_internals = [
("_suffixes", InternalTraversal.dp_prefix_sequence)
]
@_generative
@_document_text_coercion(
"expr",
":meth:`_expression.HasSuffixes.suffix_with`",
":paramref:`.HasSuffixes.suffix_with.*expr`",
)
def suffix_with(self, *expr, **kw):
r"""Add one or more expressions following the statement as a whole.
This is used to support backend-specific suffix keywords on
certain constructs.
E.g.::
stmt = select([col1, col2]).cte().suffix_with(
"cycle empno set y_cycle to 1 default 0", dialect="oracle")
Multiple suffixes can be specified by multiple calls
to :meth:`_expression.HasSuffixes.suffix_with`.
:param \*expr: textual or :class:`_expression.ClauseElement`
construct which
will be rendered following the target clause.
:param \**kw: A single keyword 'dialect' is accepted. This is an
optional string dialect name which will
limit rendering of this suffix to only that dialect.
"""
dialect = kw.pop("dialect", None)
if kw:
raise exc.ArgumentError(
"Unsupported argument(s): %s" % ",".join(kw)
)
self._setup_suffixes(expr, dialect)
def _setup_suffixes(self, suffixes, dialect=None):
self._suffixes = self._suffixes + tuple(
[
(coercions.expect(roles.StatementOptionRole, p), dialect)
for p in suffixes
]
)
class HasHints(object):
_hints = util.immutabledict()
_statement_hints = ()
_has_hints_traverse_internals = [
("_statement_hints", InternalTraversal.dp_statement_hint_list),
("_hints", InternalTraversal.dp_table_hint_list),
]
def with_statement_hint(self, text, dialect_name="*"):
"""Add a statement hint to this :class:`_expression.Select` or
other selectable object.
This method is similar to :meth:`_expression.Select.with_hint`
except that
it does not require an individual table, and instead applies to the
statement as a whole.
Hints here are specific to the backend database and may include
directives such as isolation levels, file directives, fetch directives,
etc.
.. versionadded:: 1.0.0
.. seealso::
:meth:`_expression.Select.with_hint`
:meth:`_expression.Select.prefix_with` - generic SELECT prefixing
which also can suit some database-specific HINT syntaxes such as
MySQL optimizer hints
"""
return self.with_hint(None, text, dialect_name)
@_generative
def with_hint(self, selectable, text, dialect_name="*"):
r"""Add an indexing or other executional context hint for the given
selectable to this :class:`_expression.Select` or other selectable
object.
The text of the hint is rendered in the appropriate
location for the database backend in use, relative
to the given :class:`_schema.Table` or :class:`_expression.Alias`
passed as the
``selectable`` argument. The dialect implementation
typically uses Python string substitution syntax
with the token ``%(name)s`` to render the name of
the table or alias. E.g. when using Oracle, the
following::
select([mytable]).\
with_hint(mytable, "index(%(name)s ix_mytable)")
Would render SQL as::
select /*+ index(mytable ix_mytable) */ ... from mytable
The ``dialect_name`` option will limit the rendering of a particular
hint to a particular backend. Such as, to add hints for both Oracle
and Sybase simultaneously::
select([mytable]).\
with_hint(mytable, "index(%(name)s ix_mytable)", 'oracle').\
with_hint(mytable, "WITH INDEX ix_mytable", 'sybase')
.. seealso::
:meth:`_expression.Select.with_statement_hint`
"""
if selectable is None:
self._statement_hints += ((dialect_name, text),)
else:
self._hints = self._hints.union(
{
(
coercions.expect(roles.FromClauseRole, selectable),
dialect_name,
): text
}
)
class FromClause(roles.AnonymizedFromClauseRole, Selectable):
"""Represent an element that can be used within the ``FROM``
clause of a ``SELECT`` statement.
The most common forms of :class:`_expression.FromClause` are the
:class:`_schema.Table` and the :func:`_expression.select` constructs. Key
features common to all :class:`_expression.FromClause` objects include:
* a :attr:`.c` collection, which provides per-name access to a collection
of :class:`_expression.ColumnElement` objects.
* a :attr:`.primary_key` attribute, which is a collection of all those
:class:`_expression.ColumnElement`
objects that indicate the ``primary_key`` flag.
* Methods to generate various derivations of a "from" clause, including
:meth:`_expression.FromClause.alias`,
:meth:`_expression.FromClause.join`,
:meth:`_expression.FromClause.select`.
"""
__visit_name__ = "fromclause"
named_with_column = False
_hide_froms = []
schema = None
"""Define the 'schema' attribute for this :class:`_expression.FromClause`.
This is typically ``None`` for most objects except that of
:class:`_schema.Table`, where it is taken as the value of the
:paramref:`_schema.Table.schema` argument.
"""
is_selectable = True
_is_from_clause = True
_is_join = False
_use_schema_map = False
@util.deprecated_params(
whereclause=(
"2.0",
"The :paramref:`_sql.FromClause.select().whereclause` parameter "
"is deprecated and will be removed in version 2.0. "
"Please make use of "
"the :meth:`.Select.where` "
"method to add WHERE criteria to the SELECT statement.",
),
kwargs=(
"2.0",
"The :meth:`_sql.FromClause.select` method will no longer accept "
"keyword arguments in version 2.0. Please use generative methods "
"from the "
":class:`_sql.Select` construct in order to apply additional "
"modifications.",
),
)
def select(self, whereclause=None, **kwargs):
r"""Return a SELECT of this :class:`_expression.FromClause`.
e.g.::
stmt = some_table.select().where(some_table.c.id == 5)
:param whereclause: a WHERE clause, equivalent to calling the
:meth:`_sql.Select.where` method.
:param \**kwargs: additional keyword arguments are passed to the
legacy constructor for :class:`_sql.Select` described at
:meth:`_sql.Select.create_legacy_select`.
.. seealso::
:func:`_expression.select` - general purpose
method which allows for arbitrary column lists.
"""
if whereclause is not None:
kwargs["whereclause"] = whereclause
return Select._create_select_from_fromclause(self, [self], **kwargs)
def join(self, right, onclause=None, isouter=False, full=False):
"""Return a :class:`_expression.Join` from this
:class:`_expression.FromClause`
to another :class:`FromClause`.
E.g.::
from sqlalchemy import join
j = user_table.join(address_table,
user_table.c.id == address_table.c.user_id)
stmt = select([user_table]).select_from(j)
would emit SQL along the lines of::
SELECT user.id, user.name FROM user
JOIN address ON user.id = address.user_id
:param right: the right side of the join; this is any
:class:`_expression.FromClause` object such as a
:class:`_schema.Table` object, and
may also be a selectable-compatible object such as an ORM-mapped
class.
:param onclause: a SQL expression representing the ON clause of the
join. If left at ``None``, :meth:`_expression.FromClause.join`
will attempt to
join the two tables based on a foreign key relationship.
:param isouter: if True, render a LEFT OUTER JOIN, instead of JOIN.
:param full: if True, render a FULL OUTER JOIN, instead of LEFT OUTER
JOIN. Implies :paramref:`.FromClause.join.isouter`.
.. versionadded:: 1.1
.. seealso::
:func:`_expression.join` - standalone function
:class:`_expression.Join` - the type of object produced
"""
return Join(self, right, onclause, isouter, full)
def outerjoin(self, right, onclause=None, full=False):
"""Return a :class:`_expression.Join` from this
:class:`_expression.FromClause`
to another :class:`FromClause`, with the "isouter" flag set to
True.
E.g.::
from sqlalchemy import outerjoin
j = user_table.outerjoin(address_table,
user_table.c.id == address_table.c.user_id)
The above is equivalent to::
j = user_table.join(
address_table,
user_table.c.id == address_table.c.user_id,
isouter=True)
:param right: the right side of the join; this is any
:class:`_expression.FromClause` object such as a
:class:`_schema.Table` object, and
may also be a selectable-compatible object such as an ORM-mapped
class.
:param onclause: a SQL expression representing the ON clause of the
join. If left at ``None``, :meth:`_expression.FromClause.join`
will attempt to
join the two tables based on a foreign key relationship.
:param full: if True, render a FULL OUTER JOIN, instead of
LEFT OUTER JOIN.
.. versionadded:: 1.1
.. seealso::
:meth:`_expression.FromClause.join`
:class:`_expression.Join`
"""
return Join(self, right, onclause, True, full)
def alias(self, name=None, flat=False):
"""Return an alias of this :class:`_expression.FromClause`.
E.g.::
a2 = some_table.alias('a2')
The above code creates an :class:`_expression.Alias`
object which can be used
as a FROM clause in any SELECT statement.
.. seealso::
:ref:`core_tutorial_aliases`
:func:`_expression.alias`
"""
return Alias._construct(self, name)
def tablesample(self, sampling, name=None, seed=None):
"""Return a TABLESAMPLE alias of this :class:`_expression.FromClause`.
The return value is the :class:`_expression.TableSample`
construct also
provided by the top-level :func:`_expression.tablesample` function.
.. versionadded:: 1.1
.. seealso::
:func:`_expression.tablesample` - usage guidelines and parameters
"""
return TableSample._construct(self, sampling, name, seed)
def is_derived_from(self, fromclause):
"""Return ``True`` if this :class:`_expression.FromClause` is
'derived' from the given ``FromClause``.
An example would be an Alias of a Table is derived from that Table.
"""
# this is essentially an "identity" check in the base class.
# Other constructs override this to traverse through
# contained elements.
return fromclause in self._cloned_set
def _is_lexical_equivalent(self, other):
"""Return ``True`` if this :class:`_expression.FromClause` and
the other represent the same lexical identity.
This tests if either one is a copy of the other, or
if they are the same via annotation identity.
"""
return self._cloned_set.intersection(other._cloned_set)
@property
def description(self):
"""A brief description of this :class:`_expression.FromClause`.
Used primarily for error message formatting.
"""
return getattr(self, "name", self.__class__.__name__ + " object")
def _generate_fromclause_column_proxies(self, fromclause):
fromclause._columns._populate_separate_keys(
col._make_proxy(fromclause) for col in self.c
)
@property
def exported_columns(self):
"""A :class:`_expression.ColumnCollection`
that represents the "exported"
columns of this :class:`_expression.Selectable`.
The "exported" columns for a :class:`_expression.FromClause`
object are synonymous
with the :attr:`_expression.FromClause.columns` collection.
.. versionadded:: 1.4
.. seealso::
:attr:`_expression.Selectable.exported_columns`
:attr:`_expression.SelectBase.exported_columns`
"""
return self.columns
@util.memoized_property
def columns(self):
"""A named-based collection of :class:`_expression.ColumnElement`
objects
maintained by this :class:`_expression.FromClause`.
The :attr:`.columns`, or :attr:`.c` collection, is the gateway
to the construction of SQL expressions using table-bound or
other selectable-bound columns::
select([mytable]).where(mytable.c.somecolumn == 5)
"""
if "_columns" not in self.__dict__:
self._init_collections()
self._populate_column_collection()
return self._columns.as_immutable()
@property
def entity_namespace(self):
"""Return a namespace used for name-based access in SQL expressions.
This is the namespace that is used to resolve "filter_by()" type
expressions, such as::
stmt.filter_by(address='some address')
It defaults to the ``.c`` collection, however internally it can
be overridden using the "entity_namespace" annotation to deliver
alternative results.
"""
return self.columns
@util.memoized_property
def primary_key(self):
"""Return the collection of :class:`_schema.Column` objects
which comprise the primary key of this FromClause.
"""
self._init_collections()
self._populate_column_collection()
return self.primary_key
@util.memoized_property
def foreign_keys(self):
"""Return the collection of :class:`_schema.ForeignKey` objects
which this FromClause references.
"""
self._init_collections()
self._populate_column_collection()
return self.foreign_keys
def _reset_column_collection(self):
"""Reset the attributes linked to the ``FromClause.c`` attribute.
This collection is separate from all the other memoized things
as it has shown to be sensitive to being cleared out in situations
where enclosing code, typically in a replacement traversal scenario,
has already established strong relationships
with the exported columns.
The collection is cleared for the case where a table is having a
column added to it as well as within a Join during copy internals.
"""
for key in ["_columns", "columns", "primary_key", "foreign_keys"]:
self.__dict__.pop(key, None)
c = property(
attrgetter("columns"),
doc="An alias for the :attr:`.columns` attribute.",
)
_select_iterable = property(attrgetter("columns"))
def _init_collections(self):
assert "_columns" not in self.__dict__
assert "primary_key" not in self.__dict__
assert "foreign_keys" not in self.__dict__
self._columns = ColumnCollection()
self.primary_key = ColumnSet()
self.foreign_keys = set()
@property
def _cols_populated(self):
return "_columns" in self.__dict__
def _populate_column_collection(self):
"""Called on subclasses to establish the .c collection.
Each implementation has a different way of establishing
this collection.
"""
def _refresh_for_new_column(self, column):
"""Given a column added to the .c collection of an underlying
selectable, produce the local version of that column, assuming this
selectable ultimately should proxy this column.
this is used to "ping" a derived selectable to add a new column
to its .c. collection when a Column has been added to one of the
Table objects it ultimtely derives from.
If the given selectable hasn't populated its .c. collection yet,
it should at least pass on the message to the contained selectables,
but it will return None.
This method is currently used by Declarative to allow Table
columns to be added to a partially constructed inheritance
mapping that may have already produced joins. The method
isn't public right now, as the full span of implications
and/or caveats aren't yet clear.
It's also possible that this functionality could be invoked by
default via an event, which would require that
selectables maintain a weak referencing collection of all
derivations.
"""
self._reset_column_collection()
class Join(roles.DMLTableRole, FromClause):
"""Represent a ``JOIN`` construct between two
:class:`_expression.FromClause`
elements.
The public constructor function for :class:`_expression.Join`
is the module-level
:func:`_expression.join()` function, as well as the
:meth:`_expression.FromClause.join` method
of any :class:`_expression.FromClause` (e.g. such as
:class:`_schema.Table`).
.. seealso::
:func:`_expression.join`
:meth:`_expression.FromClause.join`
"""
__visit_name__ = "join"
_traverse_internals = [
("left", InternalTraversal.dp_clauseelement),
("right", InternalTraversal.dp_clauseelement),
("onclause", InternalTraversal.dp_clauseelement),
("isouter", InternalTraversal.dp_boolean),
("full", InternalTraversal.dp_boolean),
]
_is_join = True
def __init__(self, left, right, onclause=None, isouter=False, full=False):
"""Construct a new :class:`_expression.Join`.
The usual entrypoint here is the :func:`_expression.join`
function or the :meth:`_expression.FromClause.join` method of any
:class:`_expression.FromClause` object.
"""
self.left = coercions.expect(
roles.FromClauseRole, left, deannotate=True
)
self.right = coercions.expect(
roles.FromClauseRole, right, deannotate=True
).self_group()
if onclause is None:
self.onclause = self._match_primaries(self.left, self.right)
else:
# note: taken from If91f61527236fd4d7ae3cad1f24c38be921c90ba
# not merged yet
self.onclause = coercions.expect(
roles.OnClauseRole, onclause
).self_group(against=operators._asbool)
self.isouter = isouter
self.full = full
@classmethod
def _create_outerjoin(cls, left, right, onclause=None, full=False):
"""Return an ``OUTER JOIN`` clause element.
The returned object is an instance of :class:`_expression.Join`.
Similar functionality is also available via the
:meth:`_expression.FromClause.outerjoin` method on any
:class:`_expression.FromClause`.
:param left: The left side of the join.
:param right: The right side of the join.
:param onclause: Optional criterion for the ``ON`` clause, is
derived from foreign key relationships established between
left and right otherwise.
To chain joins together, use the :meth:`_expression.FromClause.join`
or
:meth:`_expression.FromClause.outerjoin` methods on the resulting
:class:`_expression.Join` object.
"""
return cls(left, right, onclause, isouter=True, full=full)
@classmethod
def _create_join(
cls, left, right, onclause=None, isouter=False, full=False
):
"""Produce a :class:`_expression.Join` object, given two
:class:`_expression.FromClause`
expressions.
E.g.::
j = join(user_table, address_table,
user_table.c.id == address_table.c.user_id)
stmt = select([user_table]).select_from(j)
would emit SQL along the lines of::
SELECT user.id, user.name FROM user
JOIN address ON user.id = address.user_id
Similar functionality is available given any
:class:`_expression.FromClause` object (e.g. such as a
:class:`_schema.Table`) using
the :meth:`_expression.FromClause.join` method.
:param left: The left side of the join.
:param right: the right side of the join; this is any
:class:`_expression.FromClause` object such as a
:class:`_schema.Table` object, and
may also be a selectable-compatible object such as an ORM-mapped
class.
:param onclause: a SQL expression representing the ON clause of the
join. If left at ``None``, :meth:`_expression.FromClause.join`
will attempt to
join the two tables based on a foreign key relationship.
:param isouter: if True, render a LEFT OUTER JOIN, instead of JOIN.
:param full: if True, render a FULL OUTER JOIN, instead of JOIN.
.. versionadded:: 1.1
.. seealso::
:meth:`_expression.FromClause.join` - method form,
based on a given left side.
:class:`_expression.Join` - the type of object produced.
"""
return cls(left, right, onclause, isouter, full)
@property
def description(self):
return "Join object on %s(%d) and %s(%d)" % (
self.left.description,
id(self.left),
self.right.description,
id(self.right),
)
def is_derived_from(self, fromclause):
return (
fromclause is self
or self.left.is_derived_from(fromclause)
or self.right.is_derived_from(fromclause)
)
def self_group(self, against=None):
return FromGrouping(self)
@util.preload_module("sqlalchemy.sql.util")
def _populate_column_collection(self):
sqlutil = util.preloaded.sql_util
columns = [c for c in self.left.columns] + [
c for c in self.right.columns
]
self.primary_key.extend(
sqlutil.reduce_columns(
(c for c in columns if c.primary_key), self.onclause
)
)
self._columns._populate_separate_keys(
(col._key_label, col) for col in columns