Use custom Error class (inherits DockerException and ValueError)check_resource_not_none

2 files changed, 8 insertions, 1 deletions

diff --git a/docker/errors.py b/docker/errors.py
index fb9cb5a..d15e332 100644
--- a/docker/errors.py
+++ b/docker/errors.py
@@ -78,3 +78,7 @@ class TLSParameterError(DockerException):
                            "client configurations. See "
                            "http://docs.docker.com/examples/https/ for "
                            "API details.")
+
+
+class NullResource(DockerException, ValueError):
+    pass
diff --git a/docker/utils/decorators.py b/docker/utils/decorators.py
index 897db32..8d07f93 100644
--- a/docker/utils/decorators.py
+++ b/docker/utils/decorators.py
@@ -1,3 +1,4 @@
+import docker.errors
 
 
 def check_resource(f):
@@ -5,6 +6,8 @@ def check_resource(f):
         if resource_id is None and (
             kwargs.get('container') is None and kwargs.get('image') is None
         ):
-            raise ValueError('image or container param is None')
+            raise docker.errors.NullResource(
+                'image or container param is None'
+            )
         return f(self, resource_id, *args, **kwargs)
     return wrapped