- enhance ClauseAdapter / ColumnAdapter to have new behaviors with labels.

The "anonymize label" logic is now generalized to ClauseAdapter, and takes
place when the anonymize_labels flag is sent, taking effect for all
.columns lookups as well as within traverse() calls against the label
directly.
- traverse() will also memoize what it gets in columns, so that
calling upon traverse() / .columns against the same Label will
produce the same anonymized label.  This is so that AliasedClass
produces the same anonymized label when it is accessed per-column
(e.g. SomeAlias.some_column) as well as when it is applied to a Query,
and within column loader strategies (e.g. query(SomeAlias)); the
former uses traverse() while the latter uses .columns
- AliasedClass now calls onto ColumnAdapter
- Query also makes sure to use that same ColumnAdapter from the AliasedClass
in all cases
- update the logic from 0.9 in #1068 to make use of the same
_label_resolve_dict we use for #2992, simplifying how that works
and adding support for new scenarios that were pretty broken
(see #3148, #3188)

1 files changed, 13 insertions, 3 deletions

diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index c8504f21f..ece6bce9e 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -688,6 +688,10 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
 
     """
 
+    _allow_label_resolve = True
+    """A flag that can be flipped to prevent a column from being resolvable
+    by string label name."""
+
     _alt_names = ()
 
     def self_group(self, against=None):
@@ -704,8 +708,6 @@ class ColumnElement(operators.ColumnOperators, ClauseElement):
         else:
             return super(ColumnElement, self)._negate()
 
-    _allow_label_resolve = True
-
     @util.memoized_property
     def type(self):
         return type_api.NULLTYPE
@@ -1248,6 +1250,8 @@ class TextClause(Executable, ClauseElement):
     # interpreted in a column expression situation
     key = _label = _resolve_label = None
 
+    _allow_label_resolve = False
+
     def __init__(
             self,
             text,
@@ -2943,8 +2947,14 @@ class Label(ColumnElement):
     def get_children(self, **kwargs):
         return self.element,
 
-    def _copy_internals(self, clone=_clone, **kw):
+    def _copy_internals(self, clone=_clone, anonymize_labels=False, **kw):
         self.element = clone(self.element, **kw)
+        if anonymize_labels:
+            self.name = _anonymous_label(
+                '%%(%d %s)s' % (
+                    id(self), getattr(self.element, 'name', 'anon'))
+            )
+            self.key = self._label = self._key_label = self.name
 
     @property
     def _from_objects(self):