- The 'default' compiler is automatically copied over

when overriding the compilation of a built in
clause construct, so no KeyError is raised if the
user-defined compiler is specific to certain
backends and compilation for a different backend
is invoked. [ticket:1838]

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/sqlalchemy/ext/compiler.py b/lib/sqlalchemy/ext/compiler.py
index 68c434fd9..12f1e443d 100644
--- a/lib/sqlalchemy/ext/compiler.py
+++ b/lib/sqlalchemy/ext/compiler.py
@@ -198,9 +198,13 @@ A big part of using the compiler extension is subclassing SQLAlchemy expression
 def compiles(class_, *specs):
     def decorate(fn):
         existing = class_.__dict__.get('_compiler_dispatcher', None)
+        existing_dispatch = class_.__dict__.get('_compiler_dispatch')
         if not existing:
             existing = _dispatcher()
-
+            
+            if existing_dispatch:
+                existing.specs['default'] = existing_dispatch
+                
             # TODO: why is the lambda needed ?
             setattr(class_, '_compiler_dispatch', lambda *arg, **kw: existing(*arg, **kw))
             setattr(class_, '_compiler_dispatcher', existing)
@@ -208,6 +212,7 @@ def compiles(class_, *specs):
         if specs:
             for s in specs:
                 existing.specs[s] = fn
+
         else:
             existing.specs['default'] = fn
         return fn