From 470f7c0c68a967e853781cde039486ab93866431 Mon Sep 17 00:00:00 2001 From: Niels Lohmann Date: Mon, 29 Jun 2020 13:43:06 +0200 Subject: [PATCH] :memo: add documentation --- README.md | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/README.md b/README.md index d7492da34..1052cc0c5 100644 --- a/README.md +++ b/README.md @@ -869,6 +869,42 @@ Some important things: * In function `from_json`, use function [`at()`](https://nlohmann.github.io/json/classnlohmann_1_1basic__json_a93403e803947b86f4da2d1fb3345cf2c.html#a93403e803947b86f4da2d1fb3345cf2c) to access the object values rather than `operator[]`. In case a key does not exist, `at` throws an exception that you can handle, whereas `operator[]` exhibits undefined behavior. * You do not need to add serializers or deserializers for STL types like `std::vector`: the library already implements these. +#### Simplify your life with macros + +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: + +- `NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(name, member1, member2, ...)` is to be defined inside of the namespace of the class/struct to create code for. +- `NLOHMANN_DEFINE_TYPE_INTRUSIVE(name, member1, member2, ...)` is to be defined inside of the class/struct to create code for. This macro can also access private members. + +In both macros, the first parameter is the name of the class/struct, and all remaining parameters name the members. + +##### Examples + +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 { + private: + std::string street; + int housenumber; + int postcode; + + public: + NLOHMANN_DEFINE_TYPE_INTRUSIVE(address, street, housenumber, postcode); + }; +} +``` #### How do I convert third-party types?