Changed behavior of Select.correlate() to ignore correlations to froms that don't exist in the superquery.

1 files changed, 34 insertions, 25 deletions

diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index 490004e39..0ebcc1146 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -4980,7 +4980,7 @@ class CompoundSelect(SelectBase):
     INTERSECT_ALL = util.symbol('INTERSECT ALL')
 
     def __init__(self, keyword, *selects, **kwargs):
-        self._should_correlate = kwargs.pop('correlate', False)
+        self._auto_correlate = kwargs.pop('correlate', False)
         self.keyword = keyword
         self.selects = []
 
@@ -5159,7 +5159,7 @@ class Select(HasPrefixes, SelectBase):
         :class:`SelectBase` superclass.
 
         """
-        self._should_correlate = correlate
+        self._auto_correlate = correlate
         if distinct is not False:
             if distinct is True:
                 self._distinct = True
@@ -5232,7 +5232,7 @@ class Select(HasPrefixes, SelectBase):
 
         return froms
 
-    def _get_display_froms(self, existing_froms=None):
+    def _get_display_froms(self, existing_froms=None, asfrom=False):
         """Return the full list of 'from' clauses to be displayed.
 
         Takes into account a set of existing froms which may be
@@ -5258,25 +5258,34 @@ class Select(HasPrefixes, SelectBase):
             # using a list to maintain ordering
             froms = [f for f in froms if f not in toremove]
 
-        if len(froms) > 1 or self._correlate or self._correlate_except:
-            if self._correlate:
-                froms = [f for f in froms if f not in
-                        _cloned_intersection(froms,
-                        self._correlate)]
-            if self._correlate_except:
-                froms = [f for f in froms if f in _cloned_intersection(froms,
-                        self._correlate_except)]
-            if self._should_correlate and existing_froms:
-                froms = [f for f in froms if f not in
-                        _cloned_intersection(froms,
-                        existing_froms)]
-
-                if not len(froms):
-                    raise exc.InvalidRequestError("Select statement '%s"
-                            "' returned no FROM clauses due to "
-                            "auto-correlation; specify "
-                            "correlate(<tables>) to control "
-                            "correlation manually." % self)
+        if self._correlate:
+            froms = [
+                f for f in froms if f not in
+                _cloned_intersection(
+                    _cloned_intersection(froms, existing_froms or ()),
+                    self._correlate
+                )
+            ]
+        if self._correlate_except:
+            froms = [
+                f for f in froms if f in
+                _cloned_intersection(
+                    froms,
+                    self._correlate_except
+                )
+            ]
+        if self._auto_correlate and existing_froms and len(froms) > 1 and not asfrom:
+            froms = [
+                f for f in froms if f not in
+                _cloned_intersection(froms, existing_froms)
+            ]
+
+            if not len(froms):
+                raise exc.InvalidRequestError("Select statement '%s"
+                        "' returned no FROM clauses due to "
+                        "auto-correlation; specify "
+                        "correlate(<tables>) to control "
+                        "correlation manually." % self)
 
         return froms
 
@@ -5642,7 +5651,7 @@ class Select(HasPrefixes, SelectBase):
             :ref:`correlated_subqueries`
 
         """
-        self._should_correlate = False
+        self._auto_correlate = False
         if fromclauses and fromclauses[0] is None:
             self._correlate = ()
         else:
@@ -5662,7 +5671,7 @@ class Select(HasPrefixes, SelectBase):
             :ref:`correlated_subqueries`
 
         """
-        self._should_correlate = False
+        self._auto_correlate = False
         if fromclauses and fromclauses[0] is None:
             self._correlate_except = ()
         else:
@@ -5673,7 +5682,7 @@ class Select(HasPrefixes, SelectBase):
         """append the given correlation expression to this select()
         construct."""
 
-        self._should_correlate = False
+        self._auto_correlate = False
         self._correlate = set(self._correlate).union(
                 _interpret_as_from(f) for f in fromclause)