chris/OpenHome
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity
master
OpenHome/venv/Lib/site-packages/sqlalchemy/sql/dml.py

1428 lines
50 KiB
Python
Raw Permalink Normal View History

Initial commit
2021-07-21 21:33:05 +02:00
# sql/dml.py
# Copyright (C) 2009-2021 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
"""
Provide :class:`_expression.Insert`, :class:`_expression.Update` and
:class:`_expression.Delete`.
"""
from sqlalchemy.types import NullType
from . import coercions
from . import roles
from . import util as sql_util
from .base import _entity_namespace_key
from .base import _exclusive_against
from .base import _from_objects
from .base import _generative
from .base import ColumnCollection
from .base import CompileState
from .base import DialectKWArgs
from .base import Executable
from .base import HasCompileState
from .elements import BooleanClauseList
from .elements import ClauseElement
from .elements import Null
from .selectable import HasCTE
from .selectable import HasPrefixes
from .selectable import ReturnsRows
from .visitors import InternalTraversal
from .. import exc
from .. import util
from ..util import collections_abc
class DMLState(CompileState):
_no_parameters = True
_dict_parameters = None
_multi_parameters = None
_ordered_values = None
_parameter_ordering = None
_has_multi_parameters = False
isupdate = False
isdelete = False
isinsert = False
def __init__(self, statement, compiler, **kw):
raise NotImplementedError()
@property
def dml_table(self):
return self.statement.table
def _make_extra_froms(self, statement):
froms = []
all_tables = list(sql_util.tables_from_leftmost(statement.table))
seen = {all_tables[0]}
for crit in statement._where_criteria:
for item in _from_objects(crit):
if not seen.intersection(item._cloned_set):
froms.append(item)
seen.update(item._cloned_set)
froms.extend(all_tables[1:])
return froms
def _process_multi_values(self, statement):
if not statement._supports_multi_parameters:
raise exc.InvalidRequestError(
"%s construct does not support "
"multiple parameter sets." % statement.__visit_name__.upper()
)
for parameters in statement._multi_values:
multi_parameters = [
{
c.key: value
for c, value in zip(statement.table.c, parameter_set)
}
if isinstance(parameter_set, collections_abc.Sequence)
else parameter_set
for parameter_set in parameters
]
if self._no_parameters:
self._no_parameters = False
self._has_multi_parameters = True
self._multi_parameters = multi_parameters
self._dict_parameters = self._multi_parameters[0]
elif not self._has_multi_parameters:
self._cant_mix_formats_error()
else:
self._multi_parameters.extend(multi_parameters)
def _process_values(self, statement):
if self._no_parameters:
self._has_multi_parameters = False
self._dict_parameters = statement._values
self._no_parameters = False
elif self._has_multi_parameters:
self._cant_mix_formats_error()
def _process_ordered_values(self, statement):
parameters = statement._ordered_values
if self._no_parameters:
self._no_parameters = False
self._dict_parameters = dict(parameters)
self._ordered_values = parameters
self._parameter_ordering = [key for key, value in parameters]
elif self._has_multi_parameters:
self._cant_mix_formats_error()
else:
raise exc.InvalidRequestError(
"Can only invoke ordered_values() once, and not mixed "
"with any other values() call"
)
def _process_select_values(self, statement):
parameters = {
coercions.expect(roles.DMLColumnRole, name, as_key=True): Null()
for name in statement._select_names
}
if self._no_parameters:
self._no_parameters = False
self._dict_parameters = parameters
else:
# this condition normally not reachable as the Insert
# does not allow this construction to occur
assert False, "This statement already has parameters"
def _cant_mix_formats_error(self):
raise exc.InvalidRequestError(
"Can't mix single and multiple VALUES "
"formats in one INSERT statement; one style appends to a "
"list while the other replaces values, so the intent is "
"ambiguous."
)
@CompileState.plugin_for("default", "insert")
class InsertDMLState(DMLState):
isinsert = True
include_table_with_column_exprs = False
def __init__(self, statement, compiler, **kw):
self.statement = statement
self.isinsert = True
if statement._select_names:
self._process_select_values(statement)
if statement._values is not None:
self._process_values(statement)
if statement._multi_values:
self._process_multi_values(statement)
@CompileState.plugin_for("default", "update")
class UpdateDMLState(DMLState):
isupdate = True
include_table_with_column_exprs = False
def __init__(self, statement, compiler, **kw):
self.statement = statement
self.isupdate = True
self._preserve_parameter_order = statement._preserve_parameter_order
if statement._ordered_values is not None:
self._process_ordered_values(statement)
elif statement._values is not None:
self._process_values(statement)
elif statement._multi_values:
self._process_multi_values(statement)
self._extra_froms = ef = self._make_extra_froms(statement)
self.is_multitable = mt = ef and self._dict_parameters
self.include_table_with_column_exprs = (
mt and compiler.render_table_with_column_in_update_from
)
@CompileState.plugin_for("default", "delete")
class DeleteDMLState(DMLState):
isdelete = True
def __init__(self, statement, compiler, **kw):
self.statement = statement
self.isdelete = True
self._extra_froms = self._make_extra_froms(statement)
class UpdateBase(
roles.DMLRole,
HasCTE,
HasCompileState,
DialectKWArgs,
HasPrefixes,
ReturnsRows,
Executable,
ClauseElement,
):
"""Form the base for ``INSERT``, ``UPDATE``, and ``DELETE`` statements."""
__visit_name__ = "update_base"
_execution_options = Executable._execution_options.union(
{"autocommit": True}
)
_hints = util.immutabledict()
named_with_column = False
_return_defaults = None
_returning = ()
is_dml = True
@classmethod
def _constructor_20_deprecations(cls, fn_name, clsname, names):
param_to_method_lookup = dict(
whereclause=(
"The :paramref:`%(func)s.whereclause` parameter "
"will be removed "
"in SQLAlchemy 2.0. Please refer to the "
":meth:`%(classname)s.where` method."
),
values=(
"The :paramref:`%(func)s.values` parameter will be removed "
"in SQLAlchemy 2.0. Please refer to the "
":meth:`%(classname)s.values` method."
),
bind=(
"The :paramref:`%(func)s.bind` parameter will be removed in "
"SQLAlchemy 2.0. Please use explicit connection execution."
),
inline=(
"The :paramref:`%(func)s.inline` parameter will be "
"removed in "
"SQLAlchemy 2.0. Please use the "
":meth:`%(classname)s.inline` method."
),
prefixes=(
"The :paramref:`%(func)s.prefixes parameter will be "
"removed in "
"SQLAlchemy 2.0. Please use the "
":meth:`%(classname)s.prefix_with` "
"method."
),
return_defaults=(
"The :paramref:`%(func)s.return_defaults` parameter will be "
"removed in SQLAlchemy 2.0. Please use the "
":meth:`%(classname)s.return_defaults` method."
),
returning=(
"The :paramref:`%(func)s.returning` parameter will be "
"removed in SQLAlchemy 2.0. Please use the "
":meth:`%(classname)s.returning`` method."
),
preserve_parameter_order=(
"The :paramref:`%(func)s.preserve_parameter_order` parameter "
"will be removed in SQLAlchemy 2.0. Use the "
":meth:`%(classname)s.ordered_values` method with a list "
"of tuples. "
),
)
return util.deprecated_params(
**{
name: (
"2.0",
param_to_method_lookup[name]
% {
"func": "_expression.%s" % fn_name,
"classname": "_expression.%s" % clsname,
},
)
for name in names
}
)
def _generate_fromclause_column_proxies(self, fromclause):
fromclause._columns._populate_separate_keys(
col._make_proxy(fromclause) for col in self._returning
)
def params(self, *arg, **kw):
"""Set the parameters for the statement.
This method raises ``NotImplementedError`` on the base class,
and is overridden by :class:`.ValuesBase` to provide the
SET/VALUES clause of UPDATE and INSERT.
"""
raise NotImplementedError(
"params() is not supported for INSERT/UPDATE/DELETE statements."
" To set the values for an INSERT or UPDATE statement, use"
" stmt.values(**parameters)."
)
@_generative
def with_dialect_options(self, **opt):
"""Add dialect options to this INSERT/UPDATE/DELETE object.
e.g.::
upd = table.update().dialect_options(mysql_limit=10)
.. versionadded: 1.4 - this method supersedes the dialect options
associated with the constructor.
"""
self._validate_dialect_kwargs(opt)
def _validate_dialect_kwargs_deprecated(self, dialect_kw):
util.warn_deprecated_20(
"Passing dialect keyword arguments directly to the "
"%s constructor is deprecated and will be removed in SQLAlchemy "
"2.0. Please use the ``with_dialect_options()`` method."
% (self.__class__.__name__)
)
self._validate_dialect_kwargs(dialect_kw)
def bind(self):
"""Return a 'bind' linked to this :class:`.UpdateBase`
or a :class:`_schema.Table` associated with it.
"""
return self._bind or self.table.bind
def _set_bind(self, bind):
self._bind = bind
bind = property(bind, _set_bind)
@_generative
def returning(self, *cols):
r"""Add a :term:`RETURNING` or equivalent clause to this statement.
e.g.:
.. sourcecode:: pycon+sql
>>> stmt = (
... table.update()
... .where(table.c.data == "value")
... .values(status="X")
... .returning(table.c.server_flag, table.c.updated_timestamp)
... )
>>> print(stmt)
UPDATE some_table SET status=:status
WHERE some_table.data = :data_1
RETURNING some_table.server_flag, some_table.updated_timestamp
The method may be invoked multiple times to add new entries to the
list of expressions to be returned.
.. versionadded:: 1.4.0b2 The method may be invoked multiple times to
add new entries to the list of expressions to be returned.
The given collection of column expressions should be derived from the
table that is the target of the INSERT, UPDATE, or DELETE. While
:class:`_schema.Column` objects are typical, the elements can also be
expressions:
.. sourcecode:: pycon+sql
>>> stmt = table.insert().returning(
... (table.c.first_name + " " + table.c.last_name).label("fullname")
... )
>>> print(stmt)
INSERT INTO some_table (first_name, last_name)
VALUES (:first_name, :last_name)
RETURNING some_table.first_name || :first_name_1 || some_table.last_name AS fullname
Upon compilation, a RETURNING clause, or database equivalent,
will be rendered within the statement. For INSERT and UPDATE,
the values are the newly inserted/updated values. For DELETE,
the values are those of the rows which were deleted.
Upon execution, the values of the columns to be returned are made
available via the result set and can be iterated using
:meth:`_engine.CursorResult.fetchone` and similar.
For DBAPIs which do not
natively support returning values (i.e. cx_oracle), SQLAlchemy will
approximate this behavior at the result level so that a reasonable
amount of behavioral neutrality is provided.
Note that not all databases/DBAPIs
support RETURNING. For those backends with no support,
an exception is raised upon compilation and/or execution.
For those who do support it, the functionality across backends
varies greatly, including restrictions on executemany()
and other statements which return multiple rows. Please
read the documentation notes for the database in use in
order to determine the availability of RETURNING.
.. seealso::
:meth:`.ValuesBase.return_defaults` - an alternative method tailored
towards efficient fetching of server-side defaults and triggers
for single-row INSERTs or UPDATEs.
:ref:`tutorial_insert_returning` - in the :ref:`unified_tutorial`
""" # noqa E501
if self._return_defaults:
raise exc.InvalidRequestError(
"return_defaults() is already configured on this statement"
)
self._returning += tuple(
coercions.expect(roles.ColumnsClauseRole, c) for c in cols
)
@property
def _all_selected_columns(self):
return self._returning
@property
def exported_columns(self):
"""Return the RETURNING columns as a column collection for this
statement.
.. versionadded:: 1.4
"""
# TODO: no coverage here
return ColumnCollection(
(c.key, c) for c in self._all_selected_columns
).as_immutable()
@_generative
def with_hint(self, text, selectable=None, dialect_name="*"):
"""Add a table hint for a single table to this
INSERT/UPDATE/DELETE statement.
.. note::
:meth:`.UpdateBase.with_hint` currently applies only to
Microsoft SQL Server. For MySQL INSERT/UPDATE/DELETE hints, use
:meth:`.UpdateBase.prefix_with`.
The text of the hint is rendered in the appropriate
location for the database backend in use, relative
to the :class:`_schema.Table` that is the subject of this
statement, or optionally to that of the given
:class:`_schema.Table` passed as the ``selectable`` argument.
The ``dialect_name`` option will limit the rendering of a particular
hint to a particular backend. Such as, to add a hint
that only takes effect for SQL Server::
mytable.insert().with_hint("WITH (PAGLOCK)", dialect_name="mssql")
:param text: Text of the hint.
:param selectable: optional :class:`_schema.Table` that specifies
an element of the FROM clause within an UPDATE or DELETE
to be the subject of the hint - applies only to certain backends.
:param dialect_name: defaults to ``*``, if specified as the name
of a particular dialect, will apply these hints only when
that dialect is in use.
"""
if selectable is None:
selectable = self.table
self._hints = self._hints.union({(selectable, dialect_name): text})
class ValuesBase(UpdateBase):
"""Supplies support for :meth:`.ValuesBase.values` to
INSERT and UPDATE constructs."""
__visit_name__ = "values_base"
_supports_multi_parameters = False
_preserve_parameter_order = False
select = None
_post_values_clause = None
_values = None
_multi_values = ()
_ordered_values = None
_select_names = None
_returning = ()
def __init__(self, table, values, prefixes):
self.table = coercions.expect(
roles.DMLTableRole, table, apply_propagate_attrs=self
)
if values is not None:
self.values.non_generative(self, values)
if prefixes:
self._setup_prefixes(prefixes)
@_generative
@_exclusive_against(
"_select_names",
"_ordered_values",
msgs={
"_select_names": "This construct already inserts from a SELECT",
"_ordered_values": "This statement already has ordered "
"values present",
},
)
def values(self, *args, **kwargs):
r"""Specify a fixed VALUES clause for an INSERT statement, or the SET
clause for an UPDATE.
Note that the :class:`_expression.Insert` and
:class:`_expression.Update`
constructs support
per-execution time formatting of the VALUES and/or SET clauses,
based on the arguments passed to :meth:`_engine.Connection.execute`.
However, the :meth:`.ValuesBase.values` method can be used to "fix" a
particular set of parameters into the statement.
Multiple calls to :meth:`.ValuesBase.values` will produce a new
construct, each one with the parameter list modified to include
the new parameters sent. In the typical case of a single
dictionary of parameters, the newly passed keys will replace
the same keys in the previous construct. In the case of a list-based
"multiple values" construct, each new list of values is extended
onto the existing list of values.
:param \**kwargs: key value pairs representing the string key
of a :class:`_schema.Column`
mapped to the value to be rendered into the
VALUES or SET clause::
users.insert().values(name="some name")
users.update().where(users.c.id==5).values(name="some name")
:param \*args: As an alternative to passing key/value parameters,
a dictionary, tuple, or list of dictionaries or tuples can be passed
as a single positional argument in order to form the VALUES or
SET clause of the statement. The forms that are accepted vary
based on whether this is an :class:`_expression.Insert` or an
:class:`_expression.Update` construct.
For either an :class:`_expression.Insert` or
:class:`_expression.Update`
construct, a single dictionary can be passed, which works the same as
that of the kwargs form::
users.insert().values({"name": "some name"})
users.update().values({"name": "some new name"})
Also for either form but more typically for the
:class:`_expression.Insert` construct, a tuple that contains an
entry for every column in the table is also accepted::
users.insert().values((5, "some name"))
The :class:`_expression.Insert` construct also supports being
passed a list of dictionaries or full-table-tuples, which on the
server will render the less common SQL syntax of "multiple values" -
this syntax is supported on backends such as SQLite, PostgreSQL,
MySQL, but not necessarily others::
users.insert().values([
{"name": "some name"},
{"name": "some other name"},
{"name": "yet another name"},
])
The above form would render a multiple VALUES statement similar to::
INSERT INTO users (name) VALUES
(:name_1),
(:name_2),
(:name_3)
It is essential to note that **passing multiple values is
NOT the same as using traditional executemany() form**. The above
syntax is a **special** syntax not typically used. To emit an
INSERT statement against multiple rows, the normal method is
to pass a multiple values list to the
:meth:`_engine.Connection.execute`
method, which is supported by all database backends and is generally
more efficient for a very large number of parameters.
.. seealso::
:ref:`execute_multiple` - an introduction to
the traditional Core method of multiple parameter set
invocation for INSERTs and other statements.
.. versionchanged:: 1.0.0 an INSERT that uses a multiple-VALUES
clause, even a list of length one,
implies that the :paramref:`_expression.Insert.inline`
flag is set to
True, indicating that the statement will not attempt to fetch
the "last inserted primary key" or other defaults. The
statement deals with an arbitrary number of rows, so the
:attr:`_engine.CursorResult.inserted_primary_key`
accessor does not
apply.
.. versionchanged:: 1.0.0 A multiple-VALUES INSERT now supports
columns with Python side default values and callables in the
same way as that of an "executemany" style of invocation; the
callable is invoked for each row. See :ref:`bug_3288`
for other details.
The UPDATE construct also supports rendering the SET parameters
in a specific order. For this feature refer to the
:meth:`_expression.Update.ordered_values` method.
.. seealso::
:meth:`_expression.Update.ordered_values`
"""
if args:
# positional case. this is currently expensive. we don't
# yet have positional-only args so we have to check the length.
# then we need to check multiparams vs. single dictionary.
# since the parameter format is needed in order to determine
# a cache key, we need to determine this up front.
arg = args[0]
if kwargs:
raise exc.ArgumentError(
"Can't pass positional and kwargs to values() "
"simultaneously"
)
elif len(args) > 1:
raise exc.ArgumentError(
"Only a single dictionary/tuple or list of "
"dictionaries/tuples is accepted positionally."
)
elif not self._preserve_parameter_order and isinstance(
arg, collections_abc.Sequence
):
if arg and isinstance(arg[0], (list, dict, tuple)):
self._multi_values += (arg,)
return
# tuple values
arg = {c.key: value for c, value in zip(self.table.c, arg)}
elif self._preserve_parameter_order and not isinstance(
arg, collections_abc.Sequence
):
raise ValueError(
"When preserve_parameter_order is True, "
"values() only accepts a list of 2-tuples"
)
else:
# kwarg path. this is the most common path for non-multi-params
# so this is fairly quick.
arg = kwargs
if args:
raise exc.ArgumentError(
"Only a single dictionary/tuple or list of "
"dictionaries/tuples is accepted positionally."
)
# for top level values(), convert literals to anonymous bound
# parameters at statement construction time, so that these values can
# participate in the cache key process like any other ClauseElement.
# crud.py now intercepts bound parameters with unique=True from here
# and ensures they get the "crud"-style name when rendered.
if self._preserve_parameter_order:
arg = [
(
coercions.expect(roles.DMLColumnRole, k),
coercions.expect(
roles.ExpressionElementRole,
v,
type_=NullType(),
is_crud=True,
),
)
for k, v in arg
]
self._ordered_values = arg
else:
arg = {
coercions.expect(roles.DMLColumnRole, k): coercions.expect(
roles.ExpressionElementRole,
v,
type_=NullType(),
is_crud=True,
)
for k, v in arg.items()
}
if self._values:
self._values = self._values.union(arg)
else:
self._values = util.immutabledict(arg)
@_generative
@_exclusive_against(
"_returning",
msgs={
"_returning": "RETURNING is already configured on this statement"
},
defaults={"_returning": _returning},
)
def return_defaults(self, *cols):
"""Make use of a :term:`RETURNING` clause for the purpose
of fetching server-side expressions and defaults.
E.g.::
stmt = table.insert().values(data='newdata').return_defaults()
result = connection.execute(stmt)
server_created_at = result.returned_defaults['created_at']
When used against a backend that supports RETURNING, all column
values generated by SQL expression or server-side-default will be
added to any existing RETURNING clause, provided that
:meth:`.UpdateBase.returning` is not used simultaneously. The column
values will then be available on the result using the
:attr:`_engine.CursorResult.returned_defaults` accessor as
a dictionary,
referring to values keyed to the :class:`_schema.Column`
object as well as
its ``.key``.
This method differs from :meth:`.UpdateBase.returning` in these ways:
1. :meth:`.ValuesBase.return_defaults` is only intended for use with an
INSERT or an UPDATE statement that matches exactly one row per
parameter set. While the RETURNING construct in the general sense
supports multiple rows for a multi-row UPDATE or DELETE statement,
or for special cases of INSERT that return multiple rows (e.g.
INSERT from SELECT, multi-valued VALUES clause),
:meth:`.ValuesBase.return_defaults` is intended only for an
"ORM-style" single-row INSERT/UPDATE statement. The row
returned by the statement is also consumed implicitly when
:meth:`.ValuesBase.return_defaults` is used. By contrast,
:meth:`.UpdateBase.returning` leaves the RETURNING result-set intact
with a collection of any number of rows.
2. It is compatible with the existing logic to fetch auto-generated
primary key values, also known as "implicit returning". Backends
that support RETURNING will automatically make use of RETURNING in
order to fetch the value of newly generated primary keys; while the
:meth:`.UpdateBase.returning` method circumvents this behavior,
:meth:`.ValuesBase.return_defaults` leaves it intact.
3. It can be called against any backend. Backends that don't support
RETURNING will skip the usage of the feature, rather than raising
an exception. The return value of
:attr:`_engine.CursorResult.returned_defaults` will be ``None``
4. An INSERT statement invoked with executemany() is supported if the
backend database driver supports the
``insert_executemany_returning`` feature, currently this includes
PostgreSQL with psycopg2. When executemany is used, the
:attr:`_engine.CursorResult.returned_defaults_rows` and
:attr:`_engine.CursorResult.inserted_primary_key_rows` accessors
will return the inserted defaults and primary keys.
.. versionadded:: 1.4
:meth:`.ValuesBase.return_defaults` is used by the ORM to provide
an efficient implementation for the ``eager_defaults`` feature of
:func:`.mapper`.
:param cols: optional list of column key names or
:class:`_schema.Column`
objects. If omitted, all column expressions evaluated on the server
are added to the returning list.
.. versionadded:: 0.9.0
.. seealso::
:meth:`.UpdateBase.returning`
:attr:`_engine.CursorResult.returned_defaults`
:attr:`_engine.CursorResult.returned_defaults_rows`
:attr:`_engine.CursorResult.inserted_primary_key`
:attr:`_engine.CursorResult.inserted_primary_key_rows`
"""
self._return_defaults = cols or True
class Insert(ValuesBase):
"""Represent an INSERT construct.
The :class:`_expression.Insert` object is created using the
:func:`_expression.insert()` function.
"""
__visit_name__ = "insert"
_supports_multi_parameters = True
select = None
include_insert_from_select_defaults = False
is_insert = True
_traverse_internals = (
[
("table", InternalTraversal.dp_clauseelement),
("_inline", InternalTraversal.dp_boolean),
("_select_names", InternalTraversal.dp_string_list),
("_values", InternalTraversal.dp_dml_values),
("_multi_values", InternalTraversal.dp_dml_multi_values),
("select", InternalTraversal.dp_clauseelement),
("_post_values_clause", InternalTraversal.dp_clauseelement),
("_returning", InternalTraversal.dp_clauseelement_list),
("_hints", InternalTraversal.dp_table_hint_list),
]
+ HasPrefixes._has_prefixes_traverse_internals
+ DialectKWArgs._dialect_kwargs_traverse_internals
+ Executable._executable_traverse_internals
)
@ValuesBase._constructor_20_deprecations(
"insert",
"Insert",
[
"values",
"inline",
"bind",
"prefixes",
"returning",
"return_defaults",
],
)
def __init__(
self,
table,
values=None,
inline=False,
bind=None,
prefixes=None,
returning=None,
return_defaults=False,
**dialect_kw
):
"""Construct an :class:`_expression.Insert` object.
E.g.::
from sqlalchemy import insert
stmt = (
insert(user_table).
values(name='username', fullname='Full Username')
)
Similar functionality is available via the
:meth:`_expression.TableClause.insert` method on
:class:`_schema.Table`.
.. seealso::
:ref:`coretutorial_insert_expressions` - in the
:ref:`1.x tutorial <sqlexpression_toplevel>`
:ref:`tutorial_core_insert` - in the :ref:`unified_tutorial`
:param table: :class:`_expression.TableClause`
which is the subject of the
insert.
:param values: collection of values to be inserted; see
:meth:`_expression.Insert.values`
for a description of allowed formats here.
Can be omitted entirely; a :class:`_expression.Insert` construct
will also dynamically render the VALUES clause at execution time
based on the parameters passed to :meth:`_engine.Connection.execute`.
:param inline: if True, no attempt will be made to retrieve the
SQL-generated default values to be provided within the statement;
in particular,
this allows SQL expressions to be rendered 'inline' within the
statement without the need to pre-execute them beforehand; for
backends that support "returning", this turns off the "implicit
returning" feature for the statement.
If both :paramref:`_expression.Insert.values` and compile-time bind
parameters are present, the compile-time bind parameters override the
information specified within :paramref:`_expression.Insert.values` on a
per-key basis.
The keys within :paramref:`_expression.Insert.values` can be either
:class:`~sqlalchemy.schema.Column` objects or their string
identifiers. Each key may reference one of:
* a literal data value (i.e. string, number, etc.);
* a Column object;
* a SELECT statement.
If a ``SELECT`` statement is specified which references this
``INSERT`` statement's table, the statement will be correlated
against the ``INSERT`` statement.
.. seealso::
:ref:`coretutorial_insert_expressions` - SQL Expression Tutorial
:ref:`inserts_and_updates` - SQL Expression Tutorial
"""
super(Insert, self).__init__(table, values, prefixes)
self._bind = bind
self._inline = inline
if returning:
self._returning = returning
if dialect_kw:
self._validate_dialect_kwargs_deprecated(dialect_kw)
self._return_defaults = return_defaults
@_generative
def inline(self):
"""Make this :class:`_expression.Insert` construct "inline" .
When set, no attempt will be made to retrieve the
SQL-generated default values to be provided within the statement;
in particular,
this allows SQL expressions to be rendered 'inline' within the
statement without the need to pre-execute them beforehand; for
backends that support "returning", this turns off the "implicit
returning" feature for the statement.
.. versionchanged:: 1.4 the :paramref:`_expression.Insert.inline`
parameter
is now superseded by the :meth:`_expression.Insert.inline` method.
"""
self._inline = True
@_generative
def from_select(self, names, select, include_defaults=True):
"""Return a new :class:`_expression.Insert` construct which represents
an ``INSERT...FROM SELECT`` statement.
e.g.::
sel = select(table1.c.a, table1.c.b).where(table1.c.c > 5)
ins = table2.insert().from_select(['a', 'b'], sel)
:param names: a sequence of string column names or
:class:`_schema.Column`
objects representing the target columns.
:param select: a :func:`_expression.select` construct,
:class:`_expression.FromClause`
or other construct which resolves into a
:class:`_expression.FromClause`,
such as an ORM :class:`_query.Query` object, etc. The order of
columns returned from this FROM clause should correspond to the
order of columns sent as the ``names`` parameter; while this
is not checked before passing along to the database, the database
would normally raise an exception if these column lists don't
correspond.
:param include_defaults: if True, non-server default values and
SQL expressions as specified on :class:`_schema.Column` objects
(as documented in :ref:`metadata_defaults_toplevel`) not
otherwise specified in the list of names will be rendered
into the INSERT and SELECT statements, so that these values are also
included in the data to be inserted.
.. note:: A Python-side default that uses a Python callable function
will only be invoked **once** for the whole statement, and **not
per row**.
.. versionadded:: 1.0.0 - :meth:`_expression.Insert.from_select`
now renders
Python-side and SQL expression column defaults into the
SELECT statement for columns otherwise not included in the
list of column names.
.. versionchanged:: 1.0.0 an INSERT that uses FROM SELECT
implies that the :paramref:`_expression.insert.inline`
flag is set to
True, indicating that the statement will not attempt to fetch
the "last inserted primary key" or other defaults. The statement
deals with an arbitrary number of rows, so the
:attr:`_engine.CursorResult.inserted_primary_key`
accessor does not apply.
"""
if self._values:
raise exc.InvalidRequestError(
"This construct already inserts value expressions"
)
self._select_names = names
self._inline = True
self.include_insert_from_select_defaults = include_defaults
self.select = coercions.expect(roles.DMLSelectRole, select)
class DMLWhereBase(object):
_where_criteria = ()
@_generative
def where(self, *whereclause):
"""Return a new construct with the given expression(s) added to
its WHERE clause, joined to the existing clause via AND, if any.
Both :meth:`_dml.Update.where` and :meth:`_dml.Delete.where`
support multiple-table forms, including database-specific
``UPDATE...FROM`` as well as ``DELETE..USING``. For backends that
don't have multiple-table support, a backend agnostic approach
to using multiple tables is to make use of correlated subqueries.
See the linked tutorial sections below for examples.
.. seealso::
**1.x Tutorial Examples**
:ref:`tutorial_1x_correlated_updates`
:ref:`multi_table_updates`
:ref:`multi_table_deletes`
**2.0 Tutorial Examples**
:ref:`tutorial_correlated_updates`
:ref:`tutorial_update_from`
:ref:`tutorial_multi_table_deletes`
"""
for criterion in whereclause:
where_criteria = coercions.expect(roles.WhereHavingRole, criterion)
self._where_criteria += (where_criteria,)
def filter(self, *criteria):
"""A synonym for the :meth:`_dml.DMLWhereBase.where` method.
.. versionadded:: 1.4
"""
return self.where(*criteria)
def _filter_by_zero(self):
return self.table
def filter_by(self, **kwargs):
r"""apply the given filtering criterion as a WHERE clause
to this select.
"""
from_entity = self._filter_by_zero()
clauses = [
_entity_namespace_key(from_entity, key) == value
for key, value in kwargs.items()
]
return self.filter(*clauses)
@property
def whereclause(self):
"""Return the completed WHERE clause for this :class:`.DMLWhereBase`
statement.
This assembles the current collection of WHERE criteria
into a single :class:`_expression.BooleanClauseList` construct.
.. versionadded:: 1.4
"""
return BooleanClauseList._construct_for_whereclause(
self._where_criteria
)
class Update(DMLWhereBase, ValuesBase):
"""Represent an Update construct.
The :class:`_expression.Update` object is created using the
:func:`_expression.update()` function.
"""
__visit_name__ = "update"
is_update = True
_traverse_internals = (
[
("table", InternalTraversal.dp_clauseelement),
("_where_criteria", InternalTraversal.dp_clauseelement_list),
("_inline", InternalTraversal.dp_boolean),
("_ordered_values", InternalTraversal.dp_dml_ordered_values),
("_values", InternalTraversal.dp_dml_values),
("_returning", InternalTraversal.dp_clauseelement_list),
("_hints", InternalTraversal.dp_table_hint_list),
]
+ HasPrefixes._has_prefixes_traverse_internals
+ DialectKWArgs._dialect_kwargs_traverse_internals
+ Executable._executable_traverse_internals
)
@ValuesBase._constructor_20_deprecations(
"update",
"Update",
[
"whereclause",
"values",
"inline",
"bind",
"prefixes",
"returning",
"return_defaults",
"preserve_parameter_order",
],
)
def __init__(
self,
table,
whereclause=None,
values=None,
inline=False,
bind=None,
prefixes=None,
returning=None,
return_defaults=False,
preserve_parameter_order=False,
**dialect_kw
):
r"""Construct an :class:`_expression.Update` object.
E.g.::
from sqlalchemy import update
stmt = (
update(user_table).
where(user_table.c.id == 5).
values(name='user #5')
)
Similar functionality is available via the
:meth:`_expression.TableClause.update` method on
:class:`_schema.Table`.
.. seealso::
:ref:`inserts_and_updates` - in the
:ref:`1.x tutorial <sqlexpression_toplevel>`
:ref:`tutorial_core_update_delete` - in the :ref:`unified_tutorial`
:param table: A :class:`_schema.Table`
object representing the database
table to be updated.
:param whereclause: Optional SQL expression describing the ``WHERE``
condition of the ``UPDATE`` statement; is equivalent to using the
more modern :meth:`~Update.where()` method to specify the ``WHERE``
clause.
:param values:
Optional dictionary which specifies the ``SET`` conditions of the
``UPDATE``. If left as ``None``, the ``SET``
conditions are determined from those parameters passed to the
statement during the execution and/or compilation of the
statement. When compiled standalone without any parameters,
the ``SET`` clause generates for all columns.
Modern applications may prefer to use the generative
:meth:`_expression.Update.values` method to set the values of the
UPDATE statement.
:param inline:
if True, SQL defaults present on :class:`_schema.Column` objects via
the ``default`` keyword will be compiled 'inline' into the statement
and not pre-executed. This means that their values will not
be available in the dictionary returned from
:meth:`_engine.CursorResult.last_updated_params`.
:param preserve_parameter_order: if True, the update statement is
expected to receive parameters **only** via the
:meth:`_expression.Update.values` method,
and they must be passed as a Python
``list`` of 2-tuples. The rendered UPDATE statement will emit the SET
clause for each referenced column maintaining this order.
.. versionadded:: 1.0.10
.. seealso::
:ref:`updates_order_parameters` - illustrates the
:meth:`_expression.Update.ordered_values` method.
If both ``values`` and compile-time bind parameters are present, the
compile-time bind parameters override the information specified
within ``values`` on a per-key basis.
The keys within ``values`` can be either :class:`_schema.Column`
objects or their string identifiers (specifically the "key" of the
:class:`_schema.Column`, normally but not necessarily equivalent to
its "name"). Normally, the
:class:`_schema.Column` objects used here are expected to be
part of the target :class:`_schema.Table` that is the table
to be updated. However when using MySQL, a multiple-table
UPDATE statement can refer to columns from any of
the tables referred to in the WHERE clause.
The values referred to in ``values`` are typically:
* a literal data value (i.e. string, number, etc.)
* a SQL expression, such as a related :class:`_schema.Column`,
a scalar-returning :func:`_expression.select` construct,
etc.
When combining :func:`_expression.select` constructs within the
values clause of an :func:`_expression.update`
construct, the subquery represented
by the :func:`_expression.select` should be *correlated* to the
parent table, that is, providing criterion which links the table inside
the subquery to the outer table being updated::
users.update().values(
name=select(addresses.c.email_address).\
where(addresses.c.user_id==users.c.id).\
scalar_subquery()
)
.. seealso::
:ref:`inserts_and_updates` - SQL Expression
Language Tutorial
"""
self._preserve_parameter_order = preserve_parameter_order
super(Update, self).__init__(table, values, prefixes)
self._bind = bind
if returning:
self._returning = returning
if whereclause is not None:
self._where_criteria += (
coercions.expect(roles.WhereHavingRole, whereclause),
)
self._inline = inline
if dialect_kw:
self._validate_dialect_kwargs_deprecated(dialect_kw)
self._return_defaults = return_defaults
@_generative
def ordered_values(self, *args):
"""Specify the VALUES clause of this UPDATE statement with an explicit
parameter ordering that will be maintained in the SET clause of the
resulting UPDATE statement.
E.g.::
stmt = table.update().ordered_values(
("name", "ed"), ("ident": "foo")
)
.. seealso::
:ref:`updates_order_parameters` - full example of the
:meth:`_expression.Update.ordered_values` method.
.. versionchanged:: 1.4 The :meth:`_expression.Update.ordered_values`
method
supersedes the
:paramref:`_expression.update.preserve_parameter_order`
parameter, which will be removed in SQLAlchemy 2.0.
"""
if self._values:
raise exc.ArgumentError(
"This statement already has values present"
)
elif self._ordered_values:
raise exc.ArgumentError(
"This statement already has ordered values present"
)
arg = [
(
coercions.expect(roles.DMLColumnRole, k),
coercions.expect(
roles.ExpressionElementRole,
v,
type_=NullType(),
is_crud=True,
),
)
for k, v in args
]
self._ordered_values = arg
@_generative
def inline(self):
"""Make this :class:`_expression.Update` construct "inline" .
When set, SQL defaults present on :class:`_schema.Column`
objects via the
``default`` keyword will be compiled 'inline' into the statement and
not pre-executed. This means that their values will not be available
in the dictionary returned from
:meth:`_engine.CursorResult.last_updated_params`.
.. versionchanged:: 1.4 the :paramref:`_expression.update.inline`
parameter
is now superseded by the :meth:`_expression.Update.inline` method.
"""
self._inline = True
class Delete(DMLWhereBase, UpdateBase):
"""Represent a DELETE construct.
The :class:`_expression.Delete` object is created using the
:func:`_expression.delete()` function.
"""
__visit_name__ = "delete"
is_delete = True
_traverse_internals = (
[
("table", InternalTraversal.dp_clauseelement),
("_where_criteria", InternalTraversal.dp_clauseelement_list),
("_returning", InternalTraversal.dp_clauseelement_list),
("_hints", InternalTraversal.dp_table_hint_list),
]
+ HasPrefixes._has_prefixes_traverse_internals
+ DialectKWArgs._dialect_kwargs_traverse_internals
+ Executable._executable_traverse_internals
)
@ValuesBase._constructor_20_deprecations(
"delete",
"Delete",
["whereclause", "values", "bind", "prefixes", "returning"],
)
def __init__(
self,
table,
whereclause=None,
bind=None,
returning=None,
prefixes=None,
**dialect_kw
):
r"""Construct :class:`_expression.Delete` object.
E.g.::
from sqlalchemy import delete
stmt = (
delete(user_table).
where(user_table.c.id == 5)
)
Similar functionality is available via the
:meth:`_expression.TableClause.delete` method on
:class:`_schema.Table`.
.. seealso::
:ref:`inserts_and_updates` - in the
:ref:`1.x tutorial <sqlexpression_toplevel>`
:ref:`tutorial_core_update_delete` - in the :ref:`unified_tutorial`
:param table: The table to delete rows from.
:param whereclause: Optional SQL expression describing the ``WHERE``
condition of the ``DELETE`` statement; is equivalent to using the
more modern :meth:`~Delete.where()` method to specify the ``WHERE``
clause.
.. seealso::
:ref:`deletes` - SQL Expression Tutorial
"""
self._bind = bind
self.table = coercions.expect(
roles.DMLTableRole, table, apply_propagate_attrs=self
)
if returning:
self._returning = returning
if prefixes:
self._setup_prefixes(prefixes)
if whereclause is not None:
self._where_criteria += (
coercions.expect(roles.WhereHavingRole, whereclause),
)
if dialect_kw:
self._validate_dialect_kwargs_deprecated(dialect_kw)
Reference in New Issue Copy Permalink