diff options
| -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 a1e3abcb4..185c5ce37 100644 --- a/lib/sqlalchemy/sql/selectable.py +++ b/lib/sqlalchemy/sql/selectable.py @@ -2759,8 +2759,7 @@ class Select(HasPrefixes, HasSuffixes, GenerativeSelect): GenerativeSelect.__init__(self, **kwargs) - @property - def _froms(self): + def _froms_impl(self, *from_iterables): # would love to cache this, # but there's just enough edge cases, particularly now that # declarative encourages construction of SQL expressions @@ -2769,12 +2768,7 @@ class Select(HasPrefixes, HasSuffixes, GenerativeSelect): seen = set() translate = self._from_cloned - for item in itertools.chain( - _from_objects(*self._raw_columns), - _from_objects(self._whereclause) - if self._whereclause is not None else (), - self._from_obj - ): + for item in itertools.chain(*from_iterables): if item is self: raise exc.InvalidRequestError( "select() construct refers to itself as a FROM") @@ -2786,6 +2780,30 @@ class Select(HasPrefixes, HasSuffixes, GenerativeSelect): return froms + @property + def _froms(self): + return self._froms_impl( + _from_objects(*self._raw_columns), + _from_objects(self._whereclause) + if self._whereclause is not None else (), + self._from_obj) + + @property + def _display_froms(self): + if len(self._from_obj) == 0: + column_froms = set(_from_objects(*self._raw_columns)) + if len(column_froms) == 1: + # If the caller didn't specify any FROM entities, and + # they only seem to be selecting columns from one + # table, then it is very likely they expect the one + # table to be selected from. We could eliminate this + # case (as it goes against the spirit of mandating + # explicit FROMs) if we eliminated the various uses of + # Session.query(some_column). + return self._froms_impl(column_froms) + # Only use FROM entities the caller explicitly requested. + return self._froms_impl(self._from_obj) + def _get_display_froms(self, explicit_correlate_froms=None, implicit_correlate_froms=None): """Return the full list of 'from' clauses to be displayed. @@ -2796,7 +2814,7 @@ class Select(HasPrefixes, HasSuffixes, GenerativeSelect): correlating. """ - froms = self._froms + froms = self._display_froms toremove = set(itertools.chain(*[ _expand_cloned(f._hide_froms) |