From e7d7f185d4b7a11c0f02bd67a99e3f1bd123a069 Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Wed, 25 Jan 2023 11:09:51 -0800
Subject: [PATCH] Value::lookup throw NoField

---
 src/data.cpp    | 3 +++
 src/pvxs/data.h | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/src/data.cpp b/src/data.cpp
index 1a0c954..bf32579 100644
--- a/src/data.cpp
+++ b/src/data.cpp
@@ -932,6 +932,9 @@ void Value::traverse(const std::string &expr, bool modify, bool dothrow)
                 throw std::runtime_error(SB()<<"indexing syntax error or wrong field type (can't index scalar array) in '"<<expr<<"'");
         }
     }
+
+    if(!desc && dothrow)
+        throw NoField();
 }
 
 Value Value::operator[](const std::string& name)
diff --git a/src/pvxs/data.h b/src/pvxs/data.h
index bf8aa4a..283b3b2 100644
--- a/src/pvxs/data.h
+++ b/src/pvxs/data.h
@@ -733,6 +733,8 @@ public:
      * exception instead of returning an invalid Value.
      *
      * @throws LookupError If the lookup can not be satisfied
+     * @throws NoField If this Value is empty
+     * @until UNRELEASED An empty Value incorrectly returned an empty Value instead of throwing NoField
      */
     Value lookup(const std::string& name);
     const Value lookup(const std::string& name) const;