From 43b940482721a53bbc780b7f294dfb99f8bc9319 Mon Sep 17 00:00:00 2001
From: Lars Toenning <dev@ltoenning.de>
Date: Fri, 9 Feb 2024 14:05:36 +0100
Subject: [PATCH] feat: Add RequiredForJson JSON

---
 src/blackmisc/metaclass.h       | 4 +++-
 src/blackmisc/mixin/mixinjson.h | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/blackmisc/metaclass.h b/src/blackmisc/metaclass.h
index c831a8ce8..d5f663763 100644
--- a/src/blackmisc/metaclass.h
+++ b/src/blackmisc/metaclass.h
@@ -209,7 +209,8 @@ namespace BlackMisc
         DisabledForHashing = 1 << 3, //!< Element will be ignored by qHash()
         DisabledForJson = 1 << 4, //!< Element will be ignored during JSON serialization
         CaseInsensitiveComparison = 1 << 5, //!< Element will be compared case insensitively (must be a QString)
-        LosslessMarshalling = 1 << 6 //!< Element marshalling will preserve data at the expense of size
+        LosslessMarshalling = 1 << 6, //!< Element marshalling will preserve data at the expense of size
+        RequiredForJson = 1 << 7 //!< Element is required when parsing from JSON
     };
 
     /*!
@@ -229,6 +230,7 @@ namespace BlackMisc
         constexpr static MetaFlags<MetaFlag::DisabledForJson> DisabledForJson {};
         constexpr static MetaFlags<MetaFlag::CaseInsensitiveComparison> CaseInsensitiveComparison {};
         constexpr static MetaFlags<MetaFlag::LosslessMarshalling> LosslessMarshalling {};
+        constexpr static MetaFlags<MetaFlag::RequiredForJson> RequiredForJson {};
         //! @}
 
         //! Return a CMetaMemberList of type deduced from the types of the meta members.
diff --git a/src/blackmisc/mixin/mixinjson.h b/src/blackmisc/mixin/mixinjson.h
index 2a6540b7a..483fb1e6b 100644
--- a/src/blackmisc/mixin/mixinjson.h
+++ b/src/blackmisc/mixin/mixinjson.h
@@ -155,7 +155,7 @@ namespace BlackMisc
                     const auto value = json.value(CExplicitLatin1String(member.latin1Name()));
                     if (value.isUndefined())
                     {
-                        constexpr bool required = false; //! \fixme add RequiredForJson flag in metaclass system
+                        constexpr bool required = decltype(member)::has(MetaFlags<RequiredForJson>());
                         // QLatin1String used instead of QStringLiteral below since the latter causes an internal compiler bug
                         // in GCC 8 and higher
                         if (required) { throw CJsonException(QLatin1String("Missing required member '%1'").arg(member.latin1Name())); } // cppcheck-suppress knownConditionTrueFalse