added expire() function + unit test fixes [ticket:95]

2 files changed, 23 insertions, 0 deletions

diff --git a/lib/sqlalchemy/attributes.py b/lib/sqlalchemy/attributes.py
index a402a9e91..a41cdac9d 100644
--- a/lib/sqlalchemy/attributes.py
+++ b/lib/sqlalchemy/attributes.py
@@ -353,10 +353,20 @@ class AttributeManager(object):
         try:
             attr = obj.__dict__['_managed_attributes']
         except KeyError:
+            trigger = obj.__dict__.pop('_managed_trigger', None)
+            if trigger:
+                trigger()
             attr = {}
             obj.__dict__['_managed_attributes'] = attr
         return attr
 
+    def trigger_history(self, obj, callable):
+        try:
+            del obj.__dict__['_managed_attributes']
+        except KeyError:
+            pass
+        obj.__dict__['_managed_trigger'] = callable
+        
     def reset_history(self, obj, key):
         """removes the history object for the given attribute on the given object.
         When the attribute is next accessed, a new container will be created via the
diff --git a/lib/sqlalchemy/mapping/objectstore.py b/lib/sqlalchemy/mapping/objectstore.py
index d2aca8b06..be3d96934 100644
--- a/lib/sqlalchemy/mapping/objectstore.py
+++ b/lib/sqlalchemy/mapping/objectstore.py
@@ -145,9 +145,17 @@ class Session(object):
             self.uow.commit()
 
     def refresh(self, *obj):
+        """reloads the attributes for the given objects from the database, clears
+        any changes made."""
         for o in obj:
             self.uow.refresh(o)
 
+    def expire(self, *obj):
+        """invalidates the data in the given objects and sets them to refresh themselves
+        the next time they are requested."""
+        for o in obj:
+            global_attributes.trigger_history(o, lambda: refresh(o))
+
     def register_clean(self, obj):
         self._bind_to(obj)
         self.uow.register_clean(obj)
@@ -229,6 +237,11 @@ def refresh(*obj):
     """reloads the state of this object from the database, and cancels any in-memory
     changes."""
     get_session().refresh(*obj)
+
+def expire(*obj):
+    """invalidates the data in the given objects and sets them to refresh themselves
+    the next time they are requested."""
+    get_session().expire(*obj)
     
 def delete(*obj):
     """registers the given objects as to be deleted upon the next commit"""