From 37b8436ebb5d440b43da51781d52aa991a5a5f8d Mon Sep 17 00:00:00 2001
From: Mathew Sutcliffe <oktal3700@gmail.com>
Date: Wed, 29 Jun 2016 17:32:42 +0100
Subject: [PATCH] refs #679 Missing values in json should not cause members of
 default-constructed object to be overwritten.

---
 src/blackmisc/json.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/blackmisc/json.h b/src/blackmisc/json.h
index fb1c7e1a0..ad4df9348 100644
--- a/src/blackmisc/json.h
+++ b/src/blackmisc/json.h
@@ -303,7 +303,10 @@ namespace BlackMisc
             {
                 baseConvertFromJson(static_cast<BaseOfT<Derived> *>(derived()), json);
                 auto meta = introspect<Derived>().without(MetaFlags<DisabledForJson>());
-                meta.forEachMemberName(*derived(), [ & ](auto & member, const QString & name) { json.value(name) >> member; });
+                meta.forEachMemberName(*derived(), [ & ](auto & member, const QString & name)
+                {
+                    if (json.contains(name)) { json.value(name) >> member; }
+                });
             }
 
             //! Assign from JSON object string