diff options
Diffstat (limited to 'lib/sqlalchemy/sql/selectable.py')
| -rw-r--r-- | lib/sqlalchemy/sql/selectable.py | 100 |
1 files changed, 13 insertions, 87 deletions
diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py index 9d8ea8a8e..a27ff8d53 100644 --- a/lib/sqlalchemy/sql/selectable.py +++ b/lib/sqlalchemy/sql/selectable.py @@ -427,96 +427,9 @@ class FromClause(Selectable): .. versionadded:: 1.1 - .. seealso:: - - :meth:`.FromClause.join_lateral` - """ return Lateral(self, name) - def join_lateral(self, right, onclause=None, name=None): - """Return a JOIN of this FromClause to a :class:`.Table` - or :class:`.Select`, using a correlated SELECT in conjunction with - LATERAL. - - E.g.:: - - - subq = select([addresses.c.id]) - - stmt = select([users]).select_from( - users.join_lateral(subq) - ) - - Would produce the statement:: - - SELECT users.id, users.name, users.fullname - FROM users JOIN LATERAL (SELECT addresses.id AS id - FROM addresses - WHERE users.id = addresses.user_id) AS anon_1 ON true - - If ``right`` is an existing :class:`.Select` object, this - call is equivalent to:: - - left.join( - right.where(onclause).correlate(self).lateral(name), - true() - ) - - If ``right`` is a :class:`.Table`, the call is equivalent to:: - - left.join( - select([right]).where(onclause).correlate(self).lateral(name), - true() - ) - - If ``right`` is a :class:`.Alias`, the "element" of the :class:`.Alias` - is extracted and used as the right side; since we are generating - a subquery, there is never a need for the "right" side to itself - be an "alias"; the :func:`.lateral` construct provides this. - - The "onclause", if not specified, will be automatically - generated from foreign key constraints in the same way as - :meth:`.FromClause.join` if omitted; the difference between - this an a plain JOIN is that this criteria is used as the - WHERE clause of the correlated select. To use this feature, - the right side must refer to an unambiguous FROM clause to - join to; if the right side contains multiple FROM clauses besides - this one, an exception is raised and the "onclause" should be - passed explicitly. - - - .. versionadded:: 1.1 - - .. seealso:: - - :meth:`.FromClause.lateral` - - """ - - if isinstance(right, Alias): - right = right.original - - if isinstance(right, Select): - to_select = right - else: - to_select = Select([right]) - - if onclause is None: - froms = [ - f for f in to_select._froms if not f.is_derived_from(self)] - if len(froms) != 1: - raise exc.ArgumentError( - "select() passed to join_lateral has mulitple " - "FROM clauses; specify the ON clause of this " - "JOIN LATERAL explicitly.") - to_onclause = froms[0] - onclause = self.join(to_onclause).onclause - - return self.join(to_select. - where(onclause).correlate(self).lateral(name), - True_()) - def is_derived_from(self, fromclause): """Return True if this FromClause is 'derived' from the given FromClause. @@ -3099,6 +3012,19 @@ class Select(HasPrefixes, HasSuffixes, GenerativeSelect): """ self.append_from(fromclause) + def correlate_from(self, destination, onclause=None): + if onclause is None: + froms = [ + f for f in self._froms if f is not destination] + if len(froms) != 1: + raise exc.ArgumentError( + "select() has mulitple " + "FROM clauses; specify the ON clause of this " + "correlation explicitly.") + to_onclause = froms[0] + onclause = destination.join(to_onclause).onclause + return self.where(onclause).correlate(destination) + @_generative def correlate(self, *fromclauses): """return a new :class:`.Select` which will correlate the given FROM |