From d00545a669307d2fcd2aa465600bee34c30544c8 Mon Sep 17 00:00:00 2001
From: "Joshua Z. Zhang" <cheungchih@gmail.com>
Date: Wed, 20 Sep 2017 19:53:37 -0700
Subject: [PATCH] fix symbol.attr('op_name') (#149)

---
 src/core/symbolic.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/core/symbolic.cc b/src/core/symbolic.cc
index 5099e1f4920b..2b6500502f74 100644
--- a/src/core/symbolic.cc
+++ b/src/core/symbolic.cc
@@ -484,7 +484,11 @@ bool Symbol::GetAttr(const std::string& key, std::string* out) const {
     *out = node->attrs.name;
     return true;
   } else if (key == "op_name") {
-    *out = node->attrs.op->name;
+    if (node->attrs.op != nullptr) {
+      *out = node->attrs.op->name;
+    } else {
+      *out = "null";  // use null in consistant with json
+    }
     return true;
   }
   auto it = node->attrs.dict.find(key);