basic_json::update¶
// (1)
void update(const_reference j);
// (2)
void update(const_iterator first, const_iterator last);
- Inserts all values from JSON object
j
and overwrites existing keys. - Inserts all values from from range
[first, last)
and overwrites existing keys.
The function is motivated by Python's dict.update function.
Parameters¶
j
(in)- JSON object to read values from
first
(in)- begin of the range of elements to insert
last
(in)- end of the range of elements to insert
Exceptions¶
- The function can throw the following exceptions:
- Throws
type_error.312
if called on JSON values other than objects; example:"cannot use update() with string"
- Throws
- The function can throw thw following exceptions:
- Throws
type_error.312
if called on JSON values other than objects; example:"cannot use update() with string"
- Throws
invalid_iterator.202
if called on an iterator which does not belong to the current JSON value; example:"iterator does not fit current value"
- Throws
invalid_iterator.210
iffirst
andlast
do not belong to the same JSON value; example:"iterators do not fit"
- Throws
Complexity¶
- O(N*log(size() + N)), where N is the number of elements to insert.
- O(N*log(size() + N)), where N is the number of elements to insert.
Example¶
Example
The example shows how update()
is used.
#include <iostream>
#include <iomanip>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// create two JSON objects
json o1 = R"( {"color": "red", "price": 17.99} )"_json;
json o2 = R"( {"color": "blue", "speed": 100} )"_json;
// add all keys from o2 to o1 (updating "color")
o1.update(o2);
// output updated object o1
std::cout << std::setw(2) << o1 << '\n';
}
Output:
{
"color": "blue",
"price": 17.99,
"speed": 100
}
Example
The example shows how update()
is used.
#include <iostream>
#include <iomanip>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// create two JSON objects
json o1 = R"( {"color": "red", "price": 17.99} )"_json;
json o2 = R"( {"color": "blue", "speed": 100} )"_json;
// add all keys from o2 to o1 (updating "color")
o1.update(o2.begin(), o2.end());
// output updated object o1
std::cout << std::setw(2) << o1 << '\n';
}
Output:
{
"color": "blue",
"price": 17.99,
"speed": 100
}
Version history¶
- Added in version 3.0.0.