order_by_name: properly fall back to the specified languages, or identifier

Sometimes, translations are incomplete. Handle this gracefully by allowing
fallback languages. If there are none, fall back to the identifier to get
at least some order.

pokedex/db/util.py

@@ -5,6 +5,8 @@ of pokemon, and filtering/ordering by name.
 """
 
 from sqlalchemy.orm import aliased
+from sqlalchemy.sql.expression import func
+from sqlalchemy.sql.functions import coalesce
 
 from pokedex.db import tables
 
@@ -108,9 +110,10 @@ def order_by_name(query, table, language=None, *extra_languages):
 
     Uses the identifier as a fallback ordering.
     """
+    order_columns = []
     if language is None:
         query = query.outerjoin(table.names_local)
-        query = query.order_by(table.names_table.name)
+        order_columns.append(func.lower(table.names_table.name))
     else:
         extra_languages = (language, ) + extra_languages
     for language in extra_languages:
@@ -118,6 +121,7 @@ def order_by_name(query, table, language=None, *extra_languages):
         query = query.outerjoin(names_table)
         query = query.filter(names_table.foreign_id == table.id)
         query = query.filter(names_table.local_language_id == language.id)
-        query = query.order_by(names_table.name)
+        order_columns.append(func.lower(names_table.name))
-    query = query.order_by(table.identifier)
+    order_columns.append(table.identifier)
+    query = query.order_by(coalesce(*order_columns))
     return query