JSON for Modern C++  3.6.1

◆ update() [1/2]

template<template< typename U, typename V, typename... Args > class ObjectType = std::map, template< typename U, typename... Args > class ArrayType = std::vector, class StringType = std::string, class BooleanType = bool, class NumberIntegerType = std::int64_t, class NumberUnsignedType = std::uint64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator, template< typename T, typename SFINAE=void > class JSONSerializer = adl_serializer>
void nlohmann::basic_json::update ( const_reference  j)
inline

Inserts all values from JSON object j and overwrites existing keys.

Parameters
[in]jJSON object to read values from
Exceptions
type_error.312if called on JSON values other than objects; example: "cannot use update() with string"
Complexity
O(N*log(size() + N)), where N is the number of elements to insert.
Example
The example shows how update() is used.
1 #include <iostream>
2 #include <iomanip>
3 #include <nlohmann/json.hpp>
4 
5 using json = nlohmann::json;
6 
7 int main()
8 {
9  // create two JSON objects
10  json o1 = R"( {"color": "red", "price": 17.99} )"_json;
11  json o2 = R"( {"color": "blue", "speed": 100} )"_json;
12 
13  // add all keys from o2 to o1 (updating "color")
14  o1.update(o2);
15 
16  // output updated object o1
17  std::cout << std::setw(2) << o1 << '\n';
18 }
basic_json<> json
default JSON class
Definition: json.hpp:871

Output (play with this example online):
{
  "color": "blue",
  "price": 17.99,
  "speed": 100
}
The example code above can be translated with
g++ -std=c++11 -Isingle_include doc/examples/update.cpp -o update 
See also
https://docs.python.org/3.6/library/stdtypes.html#dict.update
Since
version 3.0.0

Definition at line 18076 of file json.hpp.