You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
649 lines
20 KiB
649 lines
20 KiB
# sqlalchemy/ext/baked.py
|
|
# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors
|
|
# <see AUTHORS file>
|
|
#
|
|
# This module is part of SQLAlchemy and is released under
|
|
# the MIT License: https://www.opensource.org/licenses/mit-license.php
|
|
"""Baked query extension.
|
|
|
|
Provides a creational pattern for the :class:`.query.Query` object which
|
|
allows the fully constructed object, Core select statement, and string
|
|
compiled result to be fully cached.
|
|
|
|
|
|
"""
|
|
|
|
import logging
|
|
|
|
from .. import exc as sa_exc
|
|
from .. import util
|
|
from ..orm import exc as orm_exc
|
|
from ..orm import strategy_options
|
|
from ..orm.query import Query
|
|
from ..orm.session import Session
|
|
from ..sql import func
|
|
from ..sql import literal_column
|
|
from ..sql import util as sql_util
|
|
from ..util import collections_abc
|
|
|
|
|
|
log = logging.getLogger(__name__)
|
|
|
|
|
|
class Bakery(object):
|
|
"""Callable which returns a :class:`.BakedQuery`.
|
|
|
|
This object is returned by the class method
|
|
:meth:`.BakedQuery.bakery`. It exists as an object
|
|
so that the "cache" can be easily inspected.
|
|
|
|
.. versionadded:: 1.2
|
|
|
|
|
|
"""
|
|
|
|
__slots__ = "cls", "cache"
|
|
|
|
def __init__(self, cls_, cache):
|
|
self.cls = cls_
|
|
self.cache = cache
|
|
|
|
def __call__(self, initial_fn, *args):
|
|
return self.cls(self.cache, initial_fn, args)
|
|
|
|
|
|
class BakedQuery(object):
|
|
"""A builder object for :class:`.query.Query` objects."""
|
|
|
|
__slots__ = "steps", "_bakery", "_cache_key", "_spoiled"
|
|
|
|
def __init__(self, bakery, initial_fn, args=()):
|
|
self._cache_key = ()
|
|
self._update_cache_key(initial_fn, args)
|
|
self.steps = [initial_fn]
|
|
self._spoiled = False
|
|
self._bakery = bakery
|
|
|
|
@classmethod
|
|
def bakery(cls, size=200, _size_alert=None):
|
|
"""Construct a new bakery.
|
|
|
|
:return: an instance of :class:`.Bakery`
|
|
|
|
"""
|
|
|
|
return Bakery(cls, util.LRUCache(size, size_alert=_size_alert))
|
|
|
|
def _clone(self):
|
|
b1 = BakedQuery.__new__(BakedQuery)
|
|
b1._cache_key = self._cache_key
|
|
b1.steps = list(self.steps)
|
|
b1._bakery = self._bakery
|
|
b1._spoiled = self._spoiled
|
|
return b1
|
|
|
|
def _update_cache_key(self, fn, args=()):
|
|
self._cache_key += (fn.__code__,) + args
|
|
|
|
def __iadd__(self, other):
|
|
if isinstance(other, tuple):
|
|
self.add_criteria(*other)
|
|
else:
|
|
self.add_criteria(other)
|
|
return self
|
|
|
|
def __add__(self, other):
|
|
if isinstance(other, tuple):
|
|
return self.with_criteria(*other)
|
|
else:
|
|
return self.with_criteria(other)
|
|
|
|
def add_criteria(self, fn, *args):
|
|
"""Add a criteria function to this :class:`.BakedQuery`.
|
|
|
|
This is equivalent to using the ``+=`` operator to
|
|
modify a :class:`.BakedQuery` in-place.
|
|
|
|
"""
|
|
self._update_cache_key(fn, args)
|
|
self.steps.append(fn)
|
|
return self
|
|
|
|
def with_criteria(self, fn, *args):
|
|
"""Add a criteria function to a :class:`.BakedQuery` cloned from this
|
|
one.
|
|
|
|
This is equivalent to using the ``+`` operator to
|
|
produce a new :class:`.BakedQuery` with modifications.
|
|
|
|
"""
|
|
return self._clone().add_criteria(fn, *args)
|
|
|
|
def for_session(self, session):
|
|
"""Return a :class:`_baked.Result` object for this
|
|
:class:`.BakedQuery`.
|
|
|
|
This is equivalent to calling the :class:`.BakedQuery` as a
|
|
Python callable, e.g. ``result = my_baked_query(session)``.
|
|
|
|
"""
|
|
return Result(self, session)
|
|
|
|
def __call__(self, session):
|
|
return self.for_session(session)
|
|
|
|
def spoil(self, full=False):
|
|
"""Cancel any query caching that will occur on this BakedQuery object.
|
|
|
|
The BakedQuery can continue to be used normally, however additional
|
|
creational functions will not be cached; they will be called
|
|
on every invocation.
|
|
|
|
This is to support the case where a particular step in constructing
|
|
a baked query disqualifies the query from being cacheable, such
|
|
as a variant that relies upon some uncacheable value.
|
|
|
|
:param full: if False, only functions added to this
|
|
:class:`.BakedQuery` object subsequent to the spoil step will be
|
|
non-cached; the state of the :class:`.BakedQuery` up until
|
|
this point will be pulled from the cache. If True, then the
|
|
entire :class:`_query.Query` object is built from scratch each
|
|
time, with all creational functions being called on each
|
|
invocation.
|
|
|
|
"""
|
|
if not full and not self._spoiled:
|
|
_spoil_point = self._clone()
|
|
_spoil_point._cache_key += ("_query_only",)
|
|
self.steps = [_spoil_point._retrieve_baked_query]
|
|
self._spoiled = True
|
|
return self
|
|
|
|
def _effective_key(self, session):
|
|
"""Return the key that actually goes into the cache dictionary for
|
|
this :class:`.BakedQuery`, taking into account the given
|
|
:class:`.Session`.
|
|
|
|
This basically means we also will include the session's query_class,
|
|
as the actual :class:`_query.Query` object is part of what's cached
|
|
and needs to match the type of :class:`_query.Query` that a later
|
|
session will want to use.
|
|
|
|
"""
|
|
return self._cache_key + (session._query_cls,)
|
|
|
|
def _with_lazyload_options(self, options, effective_path, cache_path=None):
|
|
"""Cloning version of _add_lazyload_options."""
|
|
q = self._clone()
|
|
q._add_lazyload_options(options, effective_path, cache_path=cache_path)
|
|
return q
|
|
|
|
def _add_lazyload_options(self, options, effective_path, cache_path=None):
|
|
"""Used by per-state lazy loaders to add options to the
|
|
"lazy load" query from a parent query.
|
|
|
|
Creates a cache key based on given load path and query options;
|
|
if a repeatable cache key cannot be generated, the query is
|
|
"spoiled" so that it won't use caching.
|
|
|
|
"""
|
|
|
|
key = ()
|
|
|
|
if not cache_path:
|
|
cache_path = effective_path
|
|
|
|
for opt in options:
|
|
if opt._is_legacy_option or opt._is_compile_state:
|
|
ck = opt._generate_cache_key()
|
|
if ck is None:
|
|
self.spoil(full=True)
|
|
else:
|
|
assert not ck[1], (
|
|
"loader options with variable bound parameters "
|
|
"not supported with baked queries. Please "
|
|
"use new-style select() statements for cached "
|
|
"ORM queries."
|
|
)
|
|
key += ck[0]
|
|
|
|
self.add_criteria(
|
|
lambda q: q._with_current_path(effective_path).options(*options),
|
|
cache_path.path,
|
|
key,
|
|
)
|
|
|
|
def _retrieve_baked_query(self, session):
|
|
query = self._bakery.get(self._effective_key(session), None)
|
|
if query is None:
|
|
query = self._as_query(session)
|
|
self._bakery[self._effective_key(session)] = query.with_session(
|
|
None
|
|
)
|
|
return query.with_session(session)
|
|
|
|
def _bake(self, session):
|
|
query = self._as_query(session)
|
|
query.session = None
|
|
|
|
# in 1.4, this is where before_compile() event is
|
|
# invoked
|
|
statement = query._statement_20()
|
|
|
|
# if the query is not safe to cache, we still do everything as though
|
|
# we did cache it, since the receiver of _bake() assumes subqueryload
|
|
# context was set up, etc.
|
|
#
|
|
# note also we want to cache the statement itself because this
|
|
# allows the statement itself to hold onto its cache key that is
|
|
# used by the Connection, which in itself is more expensive to
|
|
# generate than what BakedQuery was able to provide in 1.3 and prior
|
|
|
|
if statement._compile_options._bake_ok:
|
|
self._bakery[self._effective_key(session)] = (
|
|
query,
|
|
statement,
|
|
)
|
|
|
|
return query, statement
|
|
|
|
def to_query(self, query_or_session):
|
|
"""Return the :class:`_query.Query` object for use as a subquery.
|
|
|
|
This method should be used within the lambda callable being used
|
|
to generate a step of an enclosing :class:`.BakedQuery`. The
|
|
parameter should normally be the :class:`_query.Query` object that
|
|
is passed to the lambda::
|
|
|
|
sub_bq = self.bakery(lambda s: s.query(User.name))
|
|
sub_bq += lambda q: q.filter(
|
|
User.id == Address.user_id).correlate(Address)
|
|
|
|
main_bq = self.bakery(lambda s: s.query(Address))
|
|
main_bq += lambda q: q.filter(
|
|
sub_bq.to_query(q).exists())
|
|
|
|
In the case where the subquery is used in the first callable against
|
|
a :class:`.Session`, the :class:`.Session` is also accepted::
|
|
|
|
sub_bq = self.bakery(lambda s: s.query(User.name))
|
|
sub_bq += lambda q: q.filter(
|
|
User.id == Address.user_id).correlate(Address)
|
|
|
|
main_bq = self.bakery(
|
|
lambda s: s.query(
|
|
Address.id, sub_bq.to_query(q).scalar_subquery())
|
|
)
|
|
|
|
:param query_or_session: a :class:`_query.Query` object or a class
|
|
:class:`.Session` object, that is assumed to be within the context
|
|
of an enclosing :class:`.BakedQuery` callable.
|
|
|
|
|
|
.. versionadded:: 1.3
|
|
|
|
|
|
"""
|
|
|
|
if isinstance(query_or_session, Session):
|
|
session = query_or_session
|
|
elif isinstance(query_or_session, Query):
|
|
session = query_or_session.session
|
|
if session is None:
|
|
raise sa_exc.ArgumentError(
|
|
"Given Query needs to be associated with a Session"
|
|
)
|
|
else:
|
|
raise TypeError(
|
|
"Query or Session object expected, got %r."
|
|
% type(query_or_session)
|
|
)
|
|
return self._as_query(session)
|
|
|
|
def _as_query(self, session):
|
|
query = self.steps[0](session)
|
|
|
|
for step in self.steps[1:]:
|
|
query = step(query)
|
|
|
|
return query
|
|
|
|
|
|
class Result(object):
|
|
"""Invokes a :class:`.BakedQuery` against a :class:`.Session`.
|
|
|
|
The :class:`_baked.Result` object is where the actual :class:`.query.Query`
|
|
object gets created, or retrieved from the cache,
|
|
against a target :class:`.Session`, and is then invoked for results.
|
|
|
|
"""
|
|
|
|
__slots__ = "bq", "session", "_params", "_post_criteria"
|
|
|
|
def __init__(self, bq, session):
|
|
self.bq = bq
|
|
self.session = session
|
|
self._params = {}
|
|
self._post_criteria = []
|
|
|
|
def params(self, *args, **kw):
|
|
"""Specify parameters to be replaced into the string SQL statement."""
|
|
|
|
if len(args) == 1:
|
|
kw.update(args[0])
|
|
elif len(args) > 0:
|
|
raise sa_exc.ArgumentError(
|
|
"params() takes zero or one positional argument, "
|
|
"which is a dictionary."
|
|
)
|
|
self._params.update(kw)
|
|
return self
|
|
|
|
def _using_post_criteria(self, fns):
|
|
if fns:
|
|
self._post_criteria.extend(fns)
|
|
return self
|
|
|
|
def with_post_criteria(self, fn):
|
|
"""Add a criteria function that will be applied post-cache.
|
|
|
|
This adds a function that will be run against the
|
|
:class:`_query.Query` object after it is retrieved from the
|
|
cache. This currently includes **only** the
|
|
:meth:`_query.Query.params` and :meth:`_query.Query.execution_options`
|
|
methods.
|
|
|
|
.. warning:: :meth:`_baked.Result.with_post_criteria`
|
|
functions are applied
|
|
to the :class:`_query.Query`
|
|
object **after** the query's SQL statement
|
|
object has been retrieved from the cache. Only
|
|
:meth:`_query.Query.params` and
|
|
:meth:`_query.Query.execution_options`
|
|
methods should be used.
|
|
|
|
|
|
.. versionadded:: 1.2
|
|
|
|
|
|
"""
|
|
return self._using_post_criteria([fn])
|
|
|
|
def _as_query(self):
|
|
q = self.bq._as_query(self.session).params(self._params)
|
|
for fn in self._post_criteria:
|
|
q = fn(q)
|
|
return q
|
|
|
|
def __str__(self):
|
|
return str(self._as_query())
|
|
|
|
def __iter__(self):
|
|
return self._iter().__iter__()
|
|
|
|
def _iter(self):
|
|
bq = self.bq
|
|
|
|
if not self.session.enable_baked_queries or bq._spoiled:
|
|
return self._as_query()._iter()
|
|
|
|
query, statement = bq._bakery.get(
|
|
bq._effective_key(self.session), (None, None)
|
|
)
|
|
if query is None:
|
|
query, statement = bq._bake(self.session)
|
|
|
|
if self._params:
|
|
q = query.params(self._params)
|
|
else:
|
|
q = query
|
|
for fn in self._post_criteria:
|
|
q = fn(q)
|
|
|
|
params = q._params
|
|
execution_options = dict(q._execution_options)
|
|
execution_options.update(
|
|
{
|
|
"_sa_orm_load_options": q.load_options,
|
|
"compiled_cache": bq._bakery,
|
|
}
|
|
)
|
|
|
|
result = self.session.execute(
|
|
statement, params, execution_options=execution_options
|
|
)
|
|
if result._attributes.get("is_single_entity", False):
|
|
result = result.scalars()
|
|
|
|
if result._attributes.get("filtered", False):
|
|
result = result.unique()
|
|
|
|
return result
|
|
|
|
def count(self):
|
|
"""return the 'count'.
|
|
|
|
Equivalent to :meth:`_query.Query.count`.
|
|
|
|
Note this uses a subquery to ensure an accurate count regardless
|
|
of the structure of the original statement.
|
|
|
|
.. versionadded:: 1.1.6
|
|
|
|
"""
|
|
|
|
col = func.count(literal_column("*"))
|
|
bq = self.bq.with_criteria(lambda q: q._from_self(col))
|
|
return bq.for_session(self.session).params(self._params).scalar()
|
|
|
|
def scalar(self):
|
|
"""Return the first element of the first result or None
|
|
if no rows present. If multiple rows are returned,
|
|
raises MultipleResultsFound.
|
|
|
|
Equivalent to :meth:`_query.Query.scalar`.
|
|
|
|
.. versionadded:: 1.1.6
|
|
|
|
"""
|
|
try:
|
|
ret = self.one()
|
|
if not isinstance(ret, collections_abc.Sequence):
|
|
return ret
|
|
return ret[0]
|
|
except orm_exc.NoResultFound:
|
|
return None
|
|
|
|
def first(self):
|
|
"""Return the first row.
|
|
|
|
Equivalent to :meth:`_query.Query.first`.
|
|
|
|
"""
|
|
|
|
bq = self.bq.with_criteria(lambda q: q.slice(0, 1))
|
|
return (
|
|
bq.for_session(self.session)
|
|
.params(self._params)
|
|
._using_post_criteria(self._post_criteria)
|
|
._iter()
|
|
.first()
|
|
)
|
|
|
|
def one(self):
|
|
"""Return exactly one result or raise an exception.
|
|
|
|
Equivalent to :meth:`_query.Query.one`.
|
|
|
|
"""
|
|
return self._iter().one()
|
|
|
|
def one_or_none(self):
|
|
"""Return one or zero results, or raise an exception for multiple
|
|
rows.
|
|
|
|
Equivalent to :meth:`_query.Query.one_or_none`.
|
|
|
|
.. versionadded:: 1.0.9
|
|
|
|
"""
|
|
return self._iter().one_or_none()
|
|
|
|
def all(self):
|
|
"""Return all rows.
|
|
|
|
Equivalent to :meth:`_query.Query.all`.
|
|
|
|
"""
|
|
return self._iter().all()
|
|
|
|
def get(self, ident):
|
|
"""Retrieve an object based on identity.
|
|
|
|
Equivalent to :meth:`_query.Query.get`.
|
|
|
|
"""
|
|
|
|
query = self.bq.steps[0](self.session)
|
|
return query._get_impl(ident, self._load_on_pk_identity)
|
|
|
|
def _load_on_pk_identity(self, session, query, primary_key_identity, **kw):
|
|
"""Load the given primary key identity from the database."""
|
|
|
|
mapper = query._raw_columns[0]._annotations["parententity"]
|
|
|
|
_get_clause, _get_params = mapper._get_clause
|
|
|
|
def setup(query):
|
|
_lcl_get_clause = _get_clause
|
|
q = query._clone()
|
|
q._get_condition()
|
|
q._order_by = None
|
|
|
|
# None present in ident - turn those comparisons
|
|
# into "IS NULL"
|
|
if None in primary_key_identity:
|
|
nones = set(
|
|
[
|
|
_get_params[col].key
|
|
for col, value in zip(
|
|
mapper.primary_key, primary_key_identity
|
|
)
|
|
if value is None
|
|
]
|
|
)
|
|
_lcl_get_clause = sql_util.adapt_criterion_to_null(
|
|
_lcl_get_clause, nones
|
|
)
|
|
|
|
# TODO: can mapper._get_clause be pre-adapted?
|
|
q._where_criteria = (
|
|
sql_util._deep_annotate(_lcl_get_clause, {"_orm_adapt": True}),
|
|
)
|
|
|
|
for fn in self._post_criteria:
|
|
q = fn(q)
|
|
return q
|
|
|
|
# cache the query against a key that includes
|
|
# which positions in the primary key are NULL
|
|
# (remember, we can map to an OUTER JOIN)
|
|
bq = self.bq
|
|
|
|
# add the clause we got from mapper._get_clause to the cache
|
|
# key so that if a race causes multiple calls to _get_clause,
|
|
# we've cached on ours
|
|
bq = bq._clone()
|
|
bq._cache_key += (_get_clause,)
|
|
|
|
bq = bq.with_criteria(
|
|
setup, tuple(elem is None for elem in primary_key_identity)
|
|
)
|
|
|
|
params = dict(
|
|
[
|
|
(_get_params[primary_key].key, id_val)
|
|
for id_val, primary_key in zip(
|
|
primary_key_identity, mapper.primary_key
|
|
)
|
|
]
|
|
)
|
|
|
|
result = list(bq.for_session(self.session).params(**params))
|
|
l = len(result)
|
|
if l > 1:
|
|
raise orm_exc.MultipleResultsFound()
|
|
elif l:
|
|
return result[0]
|
|
else:
|
|
return None
|
|
|
|
|
|
@util.deprecated(
|
|
"1.2", "Baked lazy loading is now the default implementation."
|
|
)
|
|
def bake_lazy_loaders():
|
|
"""Enable the use of baked queries for all lazyloaders systemwide.
|
|
|
|
The "baked" implementation of lazy loading is now the sole implementation
|
|
for the base lazy loader; this method has no effect except for a warning.
|
|
|
|
"""
|
|
pass
|
|
|
|
|
|
@util.deprecated(
|
|
"1.2", "Baked lazy loading is now the default implementation."
|
|
)
|
|
def unbake_lazy_loaders():
|
|
"""Disable the use of baked queries for all lazyloaders systemwide.
|
|
|
|
This method now raises NotImplementedError() as the "baked" implementation
|
|
is the only lazy load implementation. The
|
|
:paramref:`_orm.relationship.bake_queries` flag may be used to disable
|
|
the caching of queries on a per-relationship basis.
|
|
|
|
"""
|
|
raise NotImplementedError(
|
|
"Baked lazy loading is now the default implementation"
|
|
)
|
|
|
|
|
|
@strategy_options.loader_option()
|
|
def baked_lazyload(loadopt, attr):
|
|
"""Indicate that the given attribute should be loaded using "lazy"
|
|
loading with a "baked" query used in the load.
|
|
|
|
"""
|
|
return loadopt.set_relationship_strategy(attr, {"lazy": "baked_select"})
|
|
|
|
|
|
@baked_lazyload._add_unbound_fn
|
|
@util.deprecated(
|
|
"1.2",
|
|
"Baked lazy loading is now the default "
|
|
"implementation for lazy loading.",
|
|
)
|
|
def baked_lazyload(*keys):
|
|
return strategy_options._UnboundLoad._from_keys(
|
|
strategy_options._UnboundLoad.baked_lazyload, keys, False, {}
|
|
)
|
|
|
|
|
|
@baked_lazyload._add_unbound_all_fn
|
|
@util.deprecated(
|
|
"1.2",
|
|
"Baked lazy loading is now the default "
|
|
"implementation for lazy loading.",
|
|
)
|
|
def baked_lazyload_all(*keys):
|
|
return strategy_options._UnboundLoad._from_keys(
|
|
strategy_options._UnboundLoad.baked_lazyload, keys, True, {}
|
|
)
|
|
|
|
|
|
baked_lazyload = baked_lazyload._unbound_fn
|
|
baked_lazyload_all = baked_lazyload_all._unbound_all_fn
|
|
|
|
bakery = BakedQuery.bakery
|