--- a/entity.py	Fri Apr 16 19:24:53 2010 +0200
+++ b/entity.py	Fri Apr 16 19:45:11 2010 +0200
@@ -269,6 +269,14 @@
         return '<Entity %s %s %s at %s>' % (
             self.e_schema, self.eid, self.keys(), id(self))
 
+    def __json_encode__(self):
+        """custom json dumps hook to dump the entity's eid
+        which is not part of dict structure itself
+        """
+        dumpable = dict(self)
+        dumpable['eid'] = self.eid
+        return dumpable
+
     def __nonzero__(self):
         return True
 

--- a/utils.py	Fri Apr 16 19:24:53 2010 +0200
+++ b/utils.py	Fri Apr 16 19:45:11 2010 +0200
@@ -347,6 +347,21 @@
 
     class CubicWebJsonEncoder(JSONEncoder):
         """define a simplejson encoder to be able to encode yams std types"""
+
+        # _iterencode is the only entry point I've found to use a custom encode
+        # hook early enough: .default() is called if nothing else matched before,
+        # .iterencode() is called once on the main structure to encode and then
+        # never gets called again.
+        # For the record, our main use case is in FormValidateController with:
+        #   dumps((status, args, entity), cls=CubicWebJsonEncoder)
+        # where we want all the entity attributes, including eid, to be part
+        # of the json object dumped.
+        # This would have once more been easier if Entity didn't extend dict.
+        def _iterencode(self, obj, markers=None):
+            if hasattr(obj, '__json_encode__'):
+                obj = obj.__json_encode__()
+            return JSONEncoder._iterencode(self, obj, markers)
+
         def default(self, obj):
             if isinstance(obj, datetime.datetime):
                 return obj.strftime('%Y/%m/%d %H:%M:%S')