Update AliasedSolrQuerySet only to support aliased names as args

parasolr/query/aliased_queryset.py

@@ -80,8 +80,14 @@ def order_by(self, *args) -> 'AliasedSolrQuerySet':
     def only(self, *args, **kwargs) -> 'AliasedSolrQuerySet':
         '''Extend :meth:`parasolr.query.queryset.SolrQuerySet.only``
         to support using aliased field names for args (but not kwargs).'''
-        args = self._unalias_args(*args)
-        return super().only(*args, **kwargs)
+
+        # convert args to aliased args, switching them to keyword
+        # args; unknown fields are treated the same way
+        kwargs.update({arg: self.field_aliases.get(arg, arg)
+                       for arg in args})
+        return super().only(**kwargs)
+
+    # also method does not need to be extended, since it runs through only
 
     def highlight(self, field: str, **kwargs) -> 'AliasedSolrQuerySet':
         '''Extend :meth:`parasolr.query.queryset.SolrQuerySet.highlight``

parasolr/query/tests/test_aliased_queryset.py

@@ -109,8 +109,12 @@ def test_order_by(self, mock_order_by):
     def test_only(self, mock_only):
         # args should be unaliased
         self.mysqs.only('name', 'year')
-        mock_only.assert_called_with(self.mysqs.field_aliases['name'],
-                                     self.mysqs.field_aliases['year'])
+        mock_only.assert_called_with(name=self.mysqs.field_aliases['name'],
+                                     year=self.mysqs.field_aliases['year'])
+
+        # field with no alias passed through as kwarg
+        self.mysqs.only('foo')
+        mock_only.assert_called_with(foo='foo')
 
         # kwargs should be ignored
         self.mysqs.only(end_year_i='end_year')