Add a helpful message to when a global_id fails to parse.

graphene/relay/node.py

@@ -90,9 +90,24 @@ def node_resolver(cls, only_type, root, info, id):
     def get_node_from_global_id(cls, info, global_id, only_type=None):
         try:
             _type, _id = cls.from_global_id(global_id)
-            graphene_type = info.schema.get_type(_type).graphene_type
-        except Exception:
-            return None
+        except Exception as e:
+            raise Exception(
+                (
+                    'Unable to parse global ID "{global_id}". '
+                    'Make sure it is a base64 encoded string in the format: "TypeName:id". '
+                    "Exception message: {exception}".format(
+                        global_id=global_id, exception=str(e)
+                    )
+                )
+            )
+
+        graphene_type = info.schema.get_type(_type)
+        if graphene_type is None:
+            raise Exception(
+                'Relay Node "{_type}" not found in schema'.format(_type=_type)
+            )
+
+        graphene_type = graphene_type.graphene_type
 
         if only_type:
             assert graphene_type == only_type, ("Must receive a {} id.").format(
@@ -101,7 +116,11 @@ def get_node_from_global_id(cls, info, global_id, only_type=None):
 
         # We make sure the ObjectType implements the "Node" interface
         if cls not in graphene_type._meta.interfaces:
-            return None
+            raise Exception(
+                'ObjectType "{_type}" does not implement the "{cls}" interface.'.format(
+                    _type=_type, cls=cls
+                )
+            )
 
         get_node = getattr(graphene_type, "get_node", None)
         if get_node:

graphene/relay/tests/test_node.py

@@ -1,3 +1,4 @@
+import re
 from graphql_relay import to_global_id
 
 from graphql.pyutils import dedent
@@ -83,14 +84,29 @@ def test_node_requesting_non_node():
     executed = schema.execute(
         '{ node(id:"%s") { __typename } } ' % Node.to_global_id("RootQuery", 1)
     )
+    assert executed.errors
+    assert re.match(
+        r"ObjectType .* does not implement the .* interface.",
+        executed.errors[0].message,
+    )
+    assert executed.data == {"node": None}
+
+
+def test_node_requesting_unknown_type():
+    executed = schema.execute(
+        '{ node(id:"%s") { __typename } } ' % Node.to_global_id("UnknownType", 1)
+    )
+    assert executed.errors
+    assert re.match(r"Relay Node .* not found in schema", executed.errors[0].message)
     assert executed.data == {"node": None}
 
 
 def test_node_query_incorrect_id():
     executed = schema.execute(
         '{ node(id:"%s") { ... on MyNode { name } } }' % "something:2"
     )
-    assert not executed.errors
+    assert executed.errors
+    assert re.match(r"Unable to parse global ID .*", executed.errors[0].message)
     assert executed.data == {"node": None}