- created a link between QueryContext and SelectionContext; the attribute

dictionary of QueryContext is now passed to SelectionContext inside
of Query.instances(), allowing messages to be passed between the two stages.
- removed the recent "exact match" behavior of Alias objects, they're back to
their usual behavior.
- tightened up the relationship between the Query's generation
  of "eager load" aliases, and Query.instances() which actually grabs the
  eagerly loaded rows.  If the aliases were not specifically generated for
  that statement by EagerLoader, the EagerLoader will not take effect
  when the rows are fetched.  This prevents columns from being grabbed accidentally
  as being part of an eager load when they were not meant for such, which can happen
  with textual SQL as well as some inheritance situations.  It's particularly important
  since the "anonymous aliasing" of columns uses simple integer counts now to generate
  labels.

1 files changed, 25 insertions, 10 deletions

diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index cb30eafcf..0c62737cb 100644
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -612,16 +612,16 @@ class Query(object):
             raise exceptions.InvalidRequestError('Multiple rows returned for one()')
     
     def __iter__(self):
-        statement = self.compile()
-        statement.use_labels = True
+        context = self._compile_context()
+        context.statement.use_labels = True
         if self._autoflush and not self._populate_existing:
             self.session._autoflush()
-        return self._execute_and_instances(statement)
+        return self._execute_and_instances(context)
     
-    def _execute_and_instances(self, statement):
-        result = self.session.execute(statement, params=self._params, mapper=self.mapper)
+    def _execute_and_instances(self, querycontext):
+        result = self.session.execute(querycontext.statement, params=self._params, mapper=self.mapper)
         try:
-            return iter(self.instances(result))
+            return iter(self.instances(result, querycontext=querycontext))
         finally:
             result.close()
 
@@ -784,10 +784,16 @@ class Query(object):
         
     def compile(self):
         """compiles and returns a SQL statement based on the criterion and conditions within this Query."""
+        return self._compile_context().statement
         
+    def _compile_context(self):
+
+        context = QueryContext(self)
+
         if self._statement:
             self._statement.use_labels = True
-            return self._statement
+            context.statement = self._statement
+            return context
         
         whereclause = self._criterion
 
@@ -807,7 +813,6 @@ class Query(object):
         
         # get/create query context.  get the ultimate compile arguments
         # from there
-        context = QueryContext(self)
         order_by = context.order_by
         from_obj = context.from_obj
         lockmode = context.lockmode
@@ -887,7 +892,7 @@ class Query(object):
                     m = clauses.adapt_clause(m)
                 statement.append_column(m)
                 
-        return statement
+        return context
 
     def _get_entity_clauses(self, m):
         """for tuples added via add_entity() or add_column(), attempt to locate
@@ -1209,17 +1214,27 @@ class SelectionContext(OperationContext):
       Indicates if mappers that have version_id columns should verify
       that instances existing already within the Session should have
       this attribute compared to the freshly loaded value.
+      
+    querycontext
+      the QueryContext, if any, used to generate the executed statement.
+      If present, the attribute dictionary from this Context will be used
+      as the basis for this SelectionContext's attribute dictionary.  This
+      allows query-compile-time operations to send messages to the 
+      result-processing-time operations.
     """
 
     def __init__(self, mapper, session, extension, **kwargs):
         self.populate_existing = kwargs.pop('populate_existing', False)
         self.version_check = kwargs.pop('version_check', False)
+        querycontext = kwargs.pop('querycontext', None)
+        if querycontext:
+            kwargs['attributes'] = querycontext.attributes
         self.session = session
         self.extension = extension
         self.identity_map = {}
         self.stack = LoaderStack()
         super(SelectionContext, self).__init__(mapper, kwargs.pop('with_options', []), **kwargs)
-
+            
     def accept_option(self, opt):
         """Accept a MapperOption which will process (modify) the state
         of this SelectionContext.