Add result map targeting for custom compiled, text objects

In order for text(), custom compiled objects, etc. to be usable
by Query(), they are all targeted by object key in the result map.
As we no longer want Query to implicitly label these, as well as that
text() has no label feature, support adding entries to the result
map that have no name, key, or type, only the object itself, and
then ensure that the compiler sets up for positional targeting
when this condition is detected.

Allows for more flexible ORM query usage with custom expressions
and text() while having less special logic in query itself.

Fixes: #4887
Change-Id: Ie073da127d292d43cb132a2b31bc90af88bfe2fd

1 files changed, 31 insertions, 31 deletions

diff --git a/lib/sqlalchemy/engine/result.py b/lib/sqlalchemy/engine/result.py
index af5303658..733bd6f6a 100644
--- a/lib/sqlalchemy/engine/result.py
+++ b/lib/sqlalchemy/engine/result.py
@@ -321,40 +321,41 @@ class ResultMetaData(object):
             # dupe records with "None" for index which results in
             # ambiguous column exception when accessed.
             if len(by_key) != num_ctx_cols:
-                seen = set()
+                # new in 1.4: get the complete set of all possible keys,
+                # strings, objects, whatever, that are dupes across two
+                # different records, first.
+                index_by_key = {}
+                dupes = set()
                 for metadata_entry in raw:
-                    key = metadata_entry[MD_RENDERED_NAME]
-                    if key in seen:
-                        # this is an "ambiguous" element, replacing
-                        # the full record in the map
-                        key = key.lower() if not self.case_sensitive else key
-                        by_key[key] = (None, (), key)
-                    seen.add(key)
-
-                # copy secondary elements from compiled columns
-                # into self._keymap, write in the potentially "ambiguous"
-                # element
+                    for key in (metadata_entry[MD_RENDERED_NAME],) + (
+                        metadata_entry[MD_OBJECTS] or ()
+                    ):
+                        if not self.case_sensitive and isinstance(
+                            key, util.string_types
+                        ):
+                            key = key.lower()
+                        idx = metadata_entry[MD_INDEX]
+                        # if this key has been associated with more than one
+                        # positional index, it's a dupe
+                        if index_by_key.setdefault(key, idx) != idx:
+                            dupes.add(key)
+
+                # then put everything we have into the keymap excluding only
+                # those keys that are dupes.
                 self._keymap.update(
                     [
-                        (obj_elem, by_key[metadata_entry[MD_LOOKUP_KEY]])
+                        (obj_elem, metadata_entry)
                         for metadata_entry in raw
                         if metadata_entry[MD_OBJECTS]
                         for obj_elem in metadata_entry[MD_OBJECTS]
+                        if obj_elem not in dupes
                     ]
                 )
 
-                # if we did a pure positional match, then reset the
-                # original "expression element" back to the "unambiguous"
-                # entry.  This is a new behavior in 1.1 which impacts
-                # TextualSelect but also straight compiled SQL constructs.
-                if not self.matched_on_name:
-                    self._keymap.update(
-                        [
-                            (metadata_entry[MD_OBJECTS][0], metadata_entry)
-                            for metadata_entry in raw
-                            if metadata_entry[MD_OBJECTS]
-                        ]
-                    )
+                # then for the dupe keys, put the "ambiguous column"
+                # record into by_key.
+                by_key.update({key: (None, (), key) for key in dupes})
+
             else:
                 # no dupes - copy secondary elements from compiled
                 # columns into self._keymap
@@ -502,16 +503,16 @@ class ResultMetaData(object):
                 (
                     idx,
                     obj,
-                    colname,
-                    colname,
+                    cursor_colname,
+                    cursor_colname,
                     context.get_result_processor(
-                        mapped_type, colname, coltype
+                        mapped_type, cursor_colname, coltype
                     ),
                     untranslated,
                 )
                 for (
                     idx,
-                    colname,
+                    cursor_colname,
                     mapped_type,
                     coltype,
                     obj,
@@ -592,7 +593,6 @@ class ResultMetaData(object):
             else:
                 mapped_type = sqltypes.NULLTYPE
                 obj = None
-
             yield idx, colname, mapped_type, coltype, obj, untranslated
 
     def _merge_cols_by_name(
@@ -758,7 +758,7 @@ class ResultMetaData(object):
         if index is None:
             raise exc.InvalidRequestError(
                 "Ambiguous column name '%s' in "
-                "result set column descriptions" % obj
+                "result set column descriptions" % rec[MD_LOOKUP_KEY]
             )
 
         return operator.methodcaller("_get_by_key_impl", index)