diff --git a/doc/mkdocs/docs/features/arbitrary_types.md b/doc/mkdocs/docs/features/arbitrary_types.md index fe80dc701..67e8a4554 100644 --- a/doc/mkdocs/docs/features/arbitrary_types.md +++ b/doc/mkdocs/docs/features/arbitrary_types.md @@ -85,29 +85,31 @@ Some important things: If you just want to serialize/deserialize some structs, the `to_json`/`from_json` functions can be a lot of boilerplate. -There are two macros to make your life easier as long as you (1) want to use a JSON object as serialization and (2) want to use the member variable names as object keys in that object: +There are four macros to make your life easier as long as you (1) want to use a JSON object as serialization and (2) want to use the member variable names as object keys in that object: -- `NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(name, member1, member2, ...)` is to be defined inside the namespace of the class/struct to create code for. -- `NLOHMANN_DEFINE_TYPE_INTRUSIVE(name, member1, member2, ...)` is to be defined inside the class/struct to create code for. This macro can also access private members. +- `NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(name, member1, member2, ...)` is to be defined inside the namespace of the class/struct to create code for. It will throw an exception in `from_json()` due to a missing value in the JSON object. +- `NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(name, member1, member2, ...)` is to be defined inside the namespace of the class/struct to create code for. It will not throw an exception in `from_json()` due to a missing value in the JSON object, but fills in values from object which is default-constructed by the type. +- `NLOHMANN_DEFINE_TYPE_INTRUSIVE(name, member1, member2, ...)` is to be defined inside the class/struct to create code for. This macro can also access private members. It will throw an exception in `from_json()` due to a missing value in the JSON object. +- `NLOHMANN_DEFINE_TYPE_INTRUSIVE_WITH_DEFAULT(name, member1, member2, ...)` is to be defined inside the class/struct to create code for. This macro can also access private members. It will not throw an exception in `from_json()` due to a missing value in the JSON object, but fills in values from object which is default-constructed by the type. -In both macros, the first parameter is the name of the class/struct, and all remaining parameters name the members. +In all macros, the first parameter is the name of the class/struct, and all remaining parameters name the members. You can read more docs about them starting from [here](macros.md#nlohmann_define_type_intrusivetype-member). !!! note - At most 64 member variables can be passed to `NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE` or `NLOHMANN_DEFINE_TYPE_INTRUSIVE`. + At most 64 member variables can be passed to these macros. ??? example The `to_json`/`from_json` functions for the `person` struct above can be created with: - + ```cpp namespace ns { NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(person, name, address, age) } ``` - + Here is an example with private members, where `NLOHMANN_DEFINE_TYPE_INTRUSIVE` is needed: - + ```cpp namespace ns { class address { @@ -115,7 +117,7 @@ In both macros, the first parameter is the name of the class/struct, and all rem std::string street; int housenumber; int postcode; - + public: NLOHMANN_DEFINE_TYPE_INTRUSIVE(address, street, housenumber, postcode) }; diff --git a/doc/mkdocs/docs/features/macros.md b/doc/mkdocs/docs/features/macros.md index 533a01e20..3d2203e72 100644 --- a/doc/mkdocs/docs/features/macros.md +++ b/doc/mkdocs/docs/features/macros.md @@ -186,12 +186,12 @@ When defined to `0`, implicit conversions are switched off. By default, implicit ??? example This is an example for an implicit conversion: - + ```cpp json j = "Hello, world!"; std::string s = j; ``` - + When `JSON_USE_IMPLICIT_CONVERSIONS` is defined to `0`, the code above does no longer compile. Instead, it must be written like this: @@ -220,6 +220,10 @@ The first parameter is the name of the class/struct, and all remaining parameter See [Simplify your life with macros](arbitrary_types.md#simplify-your-life-with-macros) for an example. +## `NLOHMANN_DEFINE_TYPE_INTRUSIVE_WITH_DEFAULT(type, member...)` + +This macro is similar to `NLOHMANN_DEFINE_TYPE_INTRUSIVE`. It will not throw an exception in `from_json()` due to a missing value in the JSON object, but can throw due to a mismatched type. In order to support that it requires that the type be default constructible. The `from_json()` function default constructs an object and uses its values as the defaults when calling the `value()` function. + ## `NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(type, member...)` This macro can be used to simplify the serialization/deserialization of types if (1) want to use a JSON object as @@ -231,6 +235,10 @@ first parameter is the name of the class/struct, and all remaining parameters na See [Simplify your life with macros](arbitrary_types.md#simplify-your-life-with-macros) for an example. +## `NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(type, member...)` + +This macro is similar to `NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE`. It will not throw an exception in `from_json()` due to a missing value in the JSON object, but can throw due to a mismatched type. In order to support that it requires that the type be default constructible. The `from_json()` function default constructs an object and uses its values as the defaults when calling the `value()` function. + ## `NLOHMANN_JSON_SERIALIZE_ENUM(type, ...)` This macro simplifies the serialization/deserialization of enum types. See diff --git a/include/nlohmann/detail/macro_scope.hpp b/include/nlohmann/detail/macro_scope.hpp index bcb70e911..87f964353 100644 --- a/include/nlohmann/detail/macro_scope.hpp +++ b/include/nlohmann/detail/macro_scope.hpp @@ -334,6 +334,7 @@ #define NLOHMANN_JSON_TO(v1) nlohmann_json_j[#v1] = nlohmann_json_t.v1; #define NLOHMANN_JSON_FROM(v1) nlohmann_json_j.at(#v1).get_to(nlohmann_json_t.v1); +#define NLOHMANN_JSON_FROM_WITH_DEFAULT(v1) nlohmann_json_t.v1 = nlohmann_json_j.value(#v1, nlohmann_json_default_obj.v1); /*! @brief macro @@ -344,6 +345,10 @@ 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) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM, __VA_ARGS__)) } +#define NLOHMANN_DEFINE_TYPE_INTRUSIVE_WITH_DEFAULT(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__)) } \ + friend void from_json(const nlohmann::json& nlohmann_json_j, Type& nlohmann_json_t) { Type nlohmann_json_default_obj; NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM_WITH_DEFAULT, __VA_ARGS__)) } + /*! @brief macro @def NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE @@ -353,6 +358,10 @@ 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_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) { Type nlohmann_json_default_obj; NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM_WITH_DEFAULT, __VA_ARGS__)) } + // inspired from https://stackoverflow.com/a/26745591 // allows to call any std function as if (e.g. with begin): diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp index 92308c557..e40e3b05b 100644 --- a/single_include/nlohmann/json.hpp +++ b/single_include/nlohmann/json.hpp @@ -2631,6 +2631,7 @@ using is_detected_convertible = #define NLOHMANN_JSON_TO(v1) nlohmann_json_j[#v1] = nlohmann_json_t.v1; #define NLOHMANN_JSON_FROM(v1) nlohmann_json_j.at(#v1).get_to(nlohmann_json_t.v1); +#define NLOHMANN_JSON_FROM_WITH_DEFAULT(v1) nlohmann_json_t.v1 = nlohmann_json_j.value(#v1, nlohmann_json_default_obj.v1); /*! @brief macro @@ -2641,6 +2642,10 @@ using is_detected_convertible = 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) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM, __VA_ARGS__)) } +#define NLOHMANN_DEFINE_TYPE_INTRUSIVE_WITH_DEFAULT(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__)) } \ + friend void from_json(const nlohmann::json& nlohmann_json_j, Type& nlohmann_json_t) { Type nlohmann_json_default_obj; NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM_WITH_DEFAULT, __VA_ARGS__)) } + /*! @brief macro @def NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE @@ -2650,6 +2655,10 @@ using is_detected_convertible = 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_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) { Type nlohmann_json_default_obj; NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM_WITH_DEFAULT, __VA_ARGS__)) } + // inspired from https://stackoverflow.com/a/26745591 // allows to call any std function as if (e.g. with begin): diff --git a/test/src/unit-udt_macro.cpp b/test/src/unit-udt_macro.cpp index 5aef22797..1762d08da 100644 --- a/test/src/unit-udt_macro.cpp +++ b/test/src/unit-udt_macro.cpp @@ -59,6 +59,42 @@ class person_with_private_data NLOHMANN_DEFINE_TYPE_INTRUSIVE(person_with_private_data, age, name, metadata) }; +class person_with_private_data_2 +{ + private: + std::string name{}; + int age = 0; + json metadata = nullptr; + + public: + bool operator==(const person_with_private_data_2& rhs) const + { + return name == rhs.name && age == rhs.age && metadata == rhs.metadata; + } + + person_with_private_data_2() = default; + person_with_private_data_2(std::string name_, int age_, json metadata_) + : name(std::move(name_)) + , age(age_) + , metadata(std::move(metadata_)) + {} + + std::string getName() const + { + return name; + } + int getAge() const + { + return age; + } + json getMetadata() const + { + return metadata; + } + + NLOHMANN_DEFINE_TYPE_INTRUSIVE_WITH_DEFAULT(person_with_private_data_2, age, name, metadata) +}; + class person_without_private_data_1 { public: @@ -103,6 +139,41 @@ class person_without_private_data_2 NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(person_without_private_data_2, age, name, metadata) +class person_without_private_data_3 +{ + public: + std::string name{}; + int age = 0; + json metadata = nullptr; + + bool operator==(const person_without_private_data_3& rhs) const + { + return name == rhs.name && age == rhs.age && metadata == rhs.metadata; + } + + person_without_private_data_3() = default; + person_without_private_data_3(std::string name_, int age_, json metadata_) + : name(std::move(name_)) + , age(age_) + , metadata(std::move(metadata_)) + {} + + std::string getName() const + { + return name; + } + int getAge() const + { + return age; + } + json getMetadata() const + { + return metadata; + } +}; + +NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT(person_without_private_data_3, age, name, metadata) + class person_with_private_alphabet { public: @@ -231,7 +302,7 @@ NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(person_with_public_alphabet, a, b, c, d, e, f } // namespace persons -TEST_CASE_TEMPLATE("Serialization/deserialization via NLOHMANN_DEFINE_TYPE_INTRUSIVE", T, +TEST_CASE_TEMPLATE("Serialization/deserialization via NLOHMANN_DEFINE_TYPE_INTRUSIVE and NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE", T, persons::person_with_private_data, persons::person_without_private_data_1, persons::person_without_private_data_2) @@ -257,6 +328,40 @@ TEST_CASE_TEMPLATE("Serialization/deserialization via NLOHMANN_DEFINE_TYPE_INTRU } } +TEST_CASE_TEMPLATE("Serialization/deserialization via NLOHMANN_DEFINE_TYPE_INTRUSIVE_WITH_DEFAULT and NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE_WITH_DEFAULT", T, + persons::person_with_private_data_2, + persons::person_without_private_data_3) +{ + SECTION("person with default values") + { + // serialization of default constructed object + T p0; + CHECK(json(p0).dump() == "{\"age\":0,\"metadata\":null,\"name\":\"\"}"); + + // serialization + T p1("Erik", 1, {{"haircuts", 2}}); + CHECK(json(p1).dump() == "{\"age\":1,\"metadata\":{\"haircuts\":2},\"name\":\"Erik\"}"); + + // deserialization + auto p2 = json(p1).get(); + CHECK(p2 == p1); + + // roundtrip + CHECK(T(json(p1)) == p1); + CHECK(json(T(json(p1))) == json(p1)); + + // check default value in case of missing field + json j = json(p1); + j.erase("name"); + j.erase("age"); + j.erase("metadata"); + T p3 = j.get(); + CHECK(p3.getName() == ""); + CHECK(p3.getAge() == 0); + CHECK(p3.getMetadata() == nullptr); + } +} + TEST_CASE_TEMPLATE("Serialization/deserialization of classes with 26 public/private member variables via NLOHMANN_DEFINE_TYPE_INTRUSIVE and NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE", T, persons::person_with_private_alphabet, persons::person_with_public_alphabet)