- [bug] A significant change to how labeling

is applied to columns in SELECT statements
allows "truncated" labels, that is label names
that are generated in Python which exceed
the maximum identifier length (note this is
configurable via label_length on create_engine()),
to be properly referenced when rendered inside
of a subquery, as well as to be present
in a result set row using their original
in-Python names.   [ticket:2396]

- apply pep8 to test_labels

2 files changed, 33 insertions, 9 deletions

diff --git a/lib/sqlalchemy/engine/base.py b/lib/sqlalchemy/engine/base.py
index db19fe7de..3175ebabd 100644
--- a/lib/sqlalchemy/engine/base.py
+++ b/lib/sqlalchemy/engine/base.py
@@ -2575,6 +2575,10 @@ class ResultMetaData(object):
         context = parent.context
         dialect = context.dialect
         typemap = dialect.dbapi_type_map
+        translate_colname = dialect._translate_colname
+
+        # high precedence key values.
+        primary_keymap = {}
 
         for i, rec in enumerate(metadata):
             colname = rec[0]
@@ -2583,6 +2587,9 @@ class ResultMetaData(object):
             if dialect.description_encoding:
                 colname = dialect._description_decoder(colname)
 
+            if translate_colname:
+                colname, untranslated = translate_colname(colname)
+
             if context.result_map:
                 try:
                     name, obj, type_ = context.result_map[colname.lower()]
@@ -2600,15 +2607,17 @@ class ResultMetaData(object):
 
             # indexes as keys. This is only needed for the Python version of
             # RowProxy (the C version uses a faster path for integer indexes).
-            keymap[i] = rec
-
-            # Column names as keys 
-            if keymap.setdefault(name.lower(), rec) is not rec: 
-                # We do not raise an exception directly because several
-                # columns colliding by name is not a problem as long as the
-                # user does not try to access them (ie use an index directly,
-                # or the more precise ColumnElement)
-                keymap[name.lower()] = (processor, obj, None)
+            primary_keymap[i] = rec
+
+            # populate primary keymap, looking for conflicts.
+            if primary_keymap.setdefault(name.lower(), rec) is not rec: 
+                # place a record that doesn't have the "index" - this
+                # is interpreted later as an AmbiguousColumnError,
+                # but only when actually accessed.   Columns 
+                # colliding by name is not a problem if those names
+                # aren't used; integer and ColumnElement access is always
+                # unambiguous.
+                primary_keymap[name.lower()] = (processor, obj, None)
 
             if dialect.requires_name_normalize:
                 colname = dialect.normalize_name(colname)
@@ -2618,10 +2627,20 @@ class ResultMetaData(object):
                 for o in obj:
                     keymap[o] = rec
 
+            if translate_colname and \
+                untranslated:
+                keymap[untranslated] = rec
+
+        # overwrite keymap values with those of the
+        # high precedence keymap.
+        keymap.update(primary_keymap)
+
         if parent._echo:
             context.engine.logger.debug(
                 "Col %r", tuple(x[0] for x in metadata))
 
+    @util.pending_deprecation("0.8", "sqlite dialect uses "
+                    "_translate_colname() now")
     def _set_keymap_synonym(self, name, origname):
         """Set a synonym for the given name.
 
diff --git a/lib/sqlalchemy/engine/default.py b/lib/sqlalchemy/engine/default.py
index 73bd7fd71..a1e5a5799 100644
--- a/lib/sqlalchemy/engine/default.py
+++ b/lib/sqlalchemy/engine/default.py
@@ -44,6 +44,7 @@ class DefaultDialect(base.Dialect):
     postfetch_lastrowid = True
     implicit_returning = False
 
+
     supports_native_enum = False
     supports_native_boolean = False
 
@@ -95,6 +96,10 @@ class DefaultDialect(base.Dialect):
     # and denormalize_name() must be provided.
     requires_name_normalize = False
 
+    # a hook for SQLite's translation of 
+    # result column names
+    _translate_colname = None
+
     reflection_options = ()
 
     def __init__(self, convert_unicode=False, assert_unicode=False,