nlohmann::adl_serializer::to_json¶
template<typename BasicJsonType, typename TargetType = ValueType>
static auto to_json(BasicJsonType& j, TargetType && val) noexcept(
noexcept(::nlohmann::to_json(j, std::forward<TargetType>(val))))
-> decltype(::nlohmann::to_json(j, std::forward<TargetType>(val)), void())
This function is usually called by the constructors of the basic_json class.
Parameters¶
j(out)- JSON value to write to
val(in)- value to read from
Examples¶
Example
The example below shows how a to_json function can be implemented for a user-defined type. This function is called by the adl_serializer when the constructor basic_json(ns::person) is called.
#include <iostream>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
namespace ns
{
// a simple struct to model a person
struct person
{
std::string name;
std::string address;
int age;
};
} // namespace ns
namespace ns
{
void to_json(json& j, const person& p)
{
j = json{ {"name", p.name}, {"address", p.address}, {"age", p.age} };
}
} // namespace ns
int main()
{
ns::person p = {"Ned Flanders", "744 Evergreen Terrace", 60};
json j = p;
std::cout << j << std::endl;
}
Output:
{"address":"744 Evergreen Terrace","age":60,"name":"Ned Flanders"}
See also¶
Version history¶
- Added in version 2.1.0.
Last update: November 1, 2023