diff options
Diffstat (limited to 'lib/sqlalchemy/sql')
| -rw-r--r-- | lib/sqlalchemy/sql/selectable.py | 36 |
1 files changed, 27 insertions, 9 deletions
diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py index e299f067e..38c8a1453 100644 --- a/lib/sqlalchemy/sql/selectable.py +++ b/lib/sqlalchemy/sql/selectable.py @@ -1673,7 +1673,7 @@ class ForUpdateArg(ClauseElement): @classmethod def parse_legacy_select(self, arg): - """Parse the for_update arugment of :func:`.select`. + """Parse the for_update argument of :func:`.select`. :param mode: Defines the lockmode to use. @@ -1688,6 +1688,12 @@ class ForUpdateArg(ClauseElement): ``'read'`` - translates to ``LOCK IN SHARE MODE`` (for MySQL), and ``FOR SHARE`` (for PostgreSQL) + ``'no_key'`` - translates to ``FOR NO KEY UPDATE`` (for PostgreSQL), + and ``FOR UPDATE`` on other backends + + ``'no_key_nowait'`` - translates to ``FOR NO KEY UPDATE NOWAIT`` (for PostgreSQL), + and ``FOR UPDATE`` on other backends + ``'read_nowait'`` - translates to ``FOR SHARE NOWAIT`` (supported by PostgreSQL). ``FOR SHARE`` and ``FOR SHARE NOWAIT`` (PostgreSQL). @@ -1696,17 +1702,21 @@ class ForUpdateArg(ClauseElement): if arg in (None, False): return None - nowait = read = False + nowait = read = no_key = False if arg == 'nowait': nowait = True elif arg == 'read': read = True elif arg == 'read_nowait': read = nowait = True + elif arg == 'no_key': + no_key = True + elif arg == 'no_key_nowait': + no_key = nowait = True elif arg is not True: raise exc.ArgumentError("Unknown for_update argument: %r" % arg) - return ForUpdateArg(read=read, nowait=nowait) + return ForUpdateArg(read=read, nowait=nowait, no_key=no_key) @property def legacy_for_update_value(self): @@ -1723,7 +1733,7 @@ class ForUpdateArg(ClauseElement): if self.of is not None: self.of = [clone(col, **kw) for col in self.of] - def __init__(self, nowait=False, read=False, of=None): + def __init__(self, nowait=False, read=False, of=None, no_key=None): """Represents arguments specified to :meth:`.Select.for_update`. .. versionadded:: 0.9.0 @@ -1731,12 +1741,16 @@ class ForUpdateArg(ClauseElement): self.nowait = nowait self.read = read + self.no_key = no_key if of is not None: self.of = [_interpret_as_column_or_from(elem) for elem in util.to_list(of)] else: self.of = None + if self.read and self.no_key: + raise exc.ArgumentError("Bad argument values: 'no_key' and 'read' cannot be True together.") + class SelectBase(HasCTE, Executable, FromClause): """Base class for SELECT statements. @@ -1873,19 +1887,23 @@ class GenerativeSelect(SelectBase): self._for_update_arg = ForUpdateArg.parse_legacy_select(value) @_generative - def with_for_update(self, nowait=False, read=False, of=None): + def with_for_update(self, nowait=False, read=False, of=None, no_key=None): """Specify a ``FOR UPDATE`` clause for this :class:`.GenerativeSelect`. E.g.:: - stmt = select([table]).with_for_update(nowait=True) + stmt = select([table]).with_for_update(nowait=True, no_key=True) - On a database like Postgresql or Oracle, the above would render a + On a database like Postgresql, the above would render a statement like:: + SELECT table.a, table.b FROM table FOR NO KEY UPDATE NOWAIT + + on Oracle:: + SELECT table.a, table.b FROM table FOR UPDATE NOWAIT - on other backends, the ``nowait`` option is ignored and instead + on other backends, the ``nowait`` and ``no_key`` options is ignored and instead would produce:: SELECT table.a, table.b FROM table FOR UPDATE @@ -1911,7 +1929,7 @@ class GenerativeSelect(SelectBase): .. versionadded:: 0.9.0 """ - self._for_update_arg = ForUpdateArg(nowait=nowait, read=read, of=of) + self._for_update_arg = ForUpdateArg(nowait=nowait, read=read, of=of, no_key=no_key) @_generative def apply_labels(self): |