diff options
Diffstat (limited to 'lib/sqlalchemy/sql/util.py')
| -rw-r--r-- | lib/sqlalchemy/sql/util.py | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/lib/sqlalchemy/sql/util.py b/lib/sqlalchemy/sql/util.py index da5e31655..7fcb45709 100644 --- a/lib/sqlalchemy/sql/util.py +++ b/lib/sqlalchemy/sql/util.py @@ -847,7 +847,7 @@ class ClauseAdapter(visitors.ReplacingExternalTraversal): return newcol @util.preload_module("sqlalchemy.sql.functions") - def replace(self, col): + def replace(self, col, _include_singleton_constants=False): functions = util.preloaded.sql_functions if isinstance(col, FromClause) and not isinstance( @@ -881,6 +881,14 @@ class ClauseAdapter(visitors.ReplacingExternalTraversal): elif not isinstance(col, ColumnElement): return None + elif not _include_singleton_constants and col._is_singleton_constant: + # dont swap out NULL, TRUE, FALSE for a label name + # in a SQL statement that's being rewritten, + # leave them as the constant. This is first noted in #6259, + # however the logic to check this moved here as of #7154 so that + # it is made specific to SQL rewriting and not all column + # correspondence + return None if "adapt_column" in col._annotations: col = col._annotations["adapt_column"] @@ -1001,8 +1009,25 @@ class ColumnAdapter(ClauseAdapter): return newcol def _locate_col(self, col): - - c = ClauseAdapter.traverse(self, col) + # both replace and traverse() are overly complicated for what + # we are doing here and we would do better to have an inlined + # version that doesn't build up as much overhead. the issue is that + # sometimes the lookup does in fact have to adapt the insides of + # say a labeled scalar subquery. However, if the object is an + # Immutable, i.e. Column objects, we can skip the "clone" / + # "copy internals" part since those will be no-ops in any case. + # additionally we want to catch singleton objects null/true/false + # and make sure they are adapted as well here. + + if col._is_immutable: + for vis in self.visitor_iterator: + c = vis.replace(col, _include_singleton_constants=True) + if c is not None: + break + else: + c = col + else: + c = ClauseAdapter.traverse(self, col) if self._wrap: c2 = self._wrap._locate_col(c) |