- Query.distinct() now accepts column expressions

  as *args, interpreted by the Postgresql dialect
  as DISTINCT ON (<expr>). [ticket:1069]
- select.distinct() now accepts column expressions
  as *args, interpreted by the Postgresql dialect
  as DISTINCT ON (<expr>).  Note this was already
  available via passing a list to the `distinct`
  keyword argument to select(). [ticket:1069]
- select.prefix_with() accepts multiple expressions
  (i.e. *expr), 'prefix' keyword argument to select()
  accepts a list or tuple.
- Passing a string to the `distinct` keyword argument
  of `select()` for the purpose of emitting special
  MySQL keywords (DISTINCTROW etc.) is deprecated -
  use `prefix_with()` for this.
- put kw arguments to select() in order
- restore docs for _SelectBase, renamed from _SelectBaseMixin

1 files changed, 13 insertions, 2 deletions

diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index 79b080927..71a6edd31 100644
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -1609,12 +1609,23 @@ class Query(object):
         self._offset = offset
 
     @_generative(_no_statement_condition)
-    def distinct(self):
+    def distinct(self, *criterion):
         """Apply a ``DISTINCT`` to the query and return the newly resulting
         ``Query``.
+        
+        :param \*expr: optional column expressions.  When present,
+         the Postgresql dialect will render a ``DISTINCT ON (<expressions>>)``
+         construct.
 
         """
-        self._distinct = True
+        if not criterion: 
+            self._distinct = True 
+        else: 
+            criterion = self._adapt_col_list(criterion)
+            if isinstance(self._distinct, list):
+                self._distinct += criterion
+            else: 
+                self._distinct = criterion 
 
     def all(self):
         """Return the results represented by this ``Query`` as a list.