Add serialization-only user defined type macros

include/nlohmann/detail/macro_scope.hpp

@@ -406,6 +406,9 @@
     friend void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) } \
     friend void from_json(const nlohmann::json& nlohmann_json_j, Type& nlohmann_json_t) { const Type nlohmann_json_default_obj{}; NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM_WITH_DEFAULT, __VA_ARGS__)) }
 
+#define NLOHMANN_DEFINE_TYPE_INTRUSIVE_ONLY_SERIALIZE(Type, ...)  \
+    friend void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) }
+
 /*!
 @brief macro
 @def NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE
@@ -415,6 +418,9 @@
     inline void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) } \
     inline void from_json(const nlohmann::json& nlohmann_json_j, Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM, __VA_ARGS__)) }
 
+#define NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_ONLY_SERIALIZE(Type, ...)  \
+    inline void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) }
+
 #define NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(Type, ...)  \
     inline void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) } \
     inline void from_json(const nlohmann::json& nlohmann_json_j, Type& nlohmann_json_t) { const Type nlohmann_json_default_obj{}; NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM_WITH_DEFAULT, __VA_ARGS__)) }

single_include/nlohmann/json.hpp

@@ -2758,6 +2758,9 @@ JSON_HEDLEY_DIAGNOSTIC_POP
     friend void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) } \
     friend void from_json(const nlohmann::json& nlohmann_json_j, Type& nlohmann_json_t) { const Type nlohmann_json_default_obj{}; NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM_WITH_DEFAULT, __VA_ARGS__)) }
 
+#define NLOHMANN_DEFINE_TYPE_INTRUSIVE_ONLY_SERIALIZE(Type, ...)  \
+    friend void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) }
+
 /*!
 @brief macro
 @def NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE
@@ -2767,6 +2770,9 @@ JSON_HEDLEY_DIAGNOSTIC_POP
     inline void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) } \
     inline void from_json(const nlohmann::json& nlohmann_json_j, Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM, __VA_ARGS__)) }
 
+#define NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_ONLY_SERIALIZE(Type, ...)  \
+    inline void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) }
+
 #define NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(Type, ...)  \
     inline void to_json(nlohmann::json& nlohmann_json_j, const Type& nlohmann_json_t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) } \
     inline void from_json(const nlohmann::json& nlohmann_json_j, Type& nlohmann_json_t) { const Type nlohmann_json_default_obj{}; NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM_WITH_DEFAULT, __VA_ARGS__)) }

tests/src/unit-udt_macro.cpp

@@ -279,6 +279,44 @@ class person_with_public_alphabet
 
 NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(person_with_public_alphabet, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z)
 
+class person_without_default_constructor_1
+{
+  public:
+    std::string name;
+    int age;
+
+    bool operator==(const person_without_default_constructor_1& other) const
+    {
+        return name == other.name && age == other.age;
+    }
+
+    person_without_default_constructor_1(std::string name_, int age_)
+        : name{std::move(name_)}
+        , age{std::move(age_)}
+    {}
+
+    NLOHMANN_DEFINE_TYPE_INTRUSIVE_ONLY_SERIALIZE(person_without_default_constructor_1, name, age);
+};
+
+class person_without_default_constructor_2
+{
+  public:
+    std::string name;
+    int age;
+
+    bool operator==(const person_without_default_constructor_2& other) const
+    {
+        return name == other.name && age == other.age;
+    }
+
+    person_without_default_constructor_2(std::string name_, int age_)
+        : name{std::move(name_)}
+        , age{std::move(age_)}
+    {}
+};
+
+NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_ONLY_SERIALIZE(person_without_default_constructor_2, name, age);
+
 } // namespace persons
 
 TEST_CASE_TEMPLATE("Serialization/deserialization via NLOHMANN_DEFINE_TYPE_INTRUSIVE and NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE", T,
@@ -412,3 +450,25 @@ TEST_CASE_TEMPLATE("Serialization/deserialization of classes with 26 public/priv
         }
     }
 }
+
+TEST_CASE_TEMPLATE("Serialization of non-default-constructible classes via NLOHMANN_DEFINE_TYPE_INTRUSIVE_ONLY_SERIALIZE and NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_ONLY_SERIALIZE", T,
+                   persons::person_without_default_constructor_1,
+                   persons::person_without_default_constructor_2)
+{
+    SECTION("person")
+    {
+        {
+            // serialization of a single object
+            T person{"Erik", 1};
+            CHECK(json(person).dump() == "{\"age\":1,\"name\":\"Erik\"}");
+
+            // serialization of a container with objects
+            std::vector<T> two_persons
+            {
+                {"Erik", 1},
+                {"Kyle", 2}
+            };
+            CHECK(json(two_persons).dump() == "[{\"age\":1,\"name\":\"Erik\"},{\"age\":2,\"name\":\"Kyle\"}]");
+        }
+    }
+}