Use this tag for questions related to nlohmann JSON C++ library
nlohmann JSON is a header-only JSON class for Modern C++ (C++11)
Latest release: 3.9.1 released on 2020-08-06
See the github project
Questions tagged [nlohmann-json]
248 questions
6
votes
1 answer
Why can't I use the [] operator to access an array in nlohmann's C++ JSON library?
I'm using this JSON library for C++ in order to get information from Twitter's API, which returns a JSON array to my program (that I'm storing in responseData). But when I try to access "name" in the returned array, it doesn't allow me to.
Here is…
Gary S
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5
votes
1 answer
reading arrays of json objects with nlohmann c++ library
I am ok using this syntax with the nlohmann library
{
"key1": {"subKey1": "value11",
"subKey2": "value12"},
"key2": {"subKey1": "value21",
"subKey2": "value22"}
}
But I have a new file, which is valid json too (I checked)…
JCSB
- 345
- 2
- 16
4
votes
3 answers
How to get number as std::string through nlohmann::json parsing?
#include
#include
#include
#include
using json = nlohmann::json;
int main()
{
std::cout.precision(std::numeric_limits::max_digits10);
// create a JSON value with different types
…
q0987
- 34,938
- 69
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- 387
4
votes
2 answers
building a nested JSON
Some data files that I need to read / parse have headers in the style:
level0var = value0
level0var.level1field = value1
level0var.level1array[11].level2field = value2
...
In other words, they look like nested C-style structs and arrays, but none…
alle_meije
- 2,424
- 1
- 19
- 40
4
votes
0 answers
nlohmann json: securely erase the keys (C++)
I'm using nlohmann/json library to represent sensitive information. Once the needed processing has been completed, I'm interested in securely erasing the keys of the json type.
Example:
json test;
test["key1"] = "value1";
test["key2"] =…
Richard Topchii
- 7,075
- 8
- 48
- 115
4
votes
3 answers
Can't get_to vector of object inside itself with Nlohmann's JSON
I've got the following code (simplified):
namespace nlohmann {
// https://github.com/nlohmann/json/issues/1749#issuecomment-772996219
template
void to_json(nlohmann::json &j, const std::optional &v) {
if (v.has_value())
j =…
Aido
- 1,524
- 3
- 18
- 41
4
votes
1 answer
How to erase item inside of item in nlohmann::json file C++
I want to know how I can delete an item within an item in the nlohmann::json C++ library.
Json example file:
{
"Users":{
"User1":{
"Name":"BOB",
"DeleteMe":"IWantToBeDeleted!"
}
}
}
What I want to…
Piboy314
- 186
- 1
- 15
4
votes
2 answers
Is there a better way to handle exceptions ? try-catch block is really ugly
I read this and find out it's important to handle exceptions, i use nlohmann::json (from github) and nearly in most of my member functions is use nlohmann::json::parse and nlohmann::json::dump which make a chance to throw exceptions if the input has…
Kate
- 561
- 4
- 11
4
votes
1 answer
How to configure the cmake file correctly to build a simple hello world for nlohmann_json?
I am using the following JSON parser: https://github.com/nlohmann/json
Following is the steps I followed to build :
2074 git clone https://github.com/nlohmann/json.git
2075 git branch
2076 ls
2077 cd json/
2078 git branch
2079 git pull
…
pranjali chumbhale
- 41
- 1
- 3
4
votes
1 answer
access json array values in c++
I'm new to c++ and trying to use nlohmann library and I'm quite stuck. I want to modify array of objects from json.
json =
{
"a": "xxxx",
"b": [{
"c": "aaa",
"d": [{
"e": "yyy"
},
{
…
Amy
- 69
- 2
- 9
4
votes
1 answer
Bizarre behavior when comparing enum class values
I was working on some JSON parsing code using the lovely nlohmann::json, and to help make useful error messages, I made myself a function to print the type of a JSON object. This function accepts a json::value_t, which is an enum class defined…
alter_igel
- 6,899
- 3
- 21
- 40
4
votes
1 answer
creating nested json object in c++ using nlohmann json
I am working with https://github.com/nlohmann/json and it works well. However I am finding difficulties to create the following json outout
{
"Id": 1,
"Child": [
{
"Id": 2
},
{
"Id": 3,
…
cateof
- 6,608
- 25
- 79
- 153
4
votes
1 answer
C++ - Convert JSON or array from it into vector
I'm using https://github.com/nlohmann/json to load JSON file into my program.
At this moment, I'm loading it:
json jsonFile;
ifstream ifs("data/test.json");
ifs >> jsonFile;
// create JSON from stream
json j_complete(jsonFile);
And I have access…
Vertisan
- 720
- 3
- 14
- 34
3
votes
1 answer
When deserializing a struct with from_json: error: no matching function for call to nlohmann::basic_json<>::get
I'm using the nlohmann/json library and trying to implement serialization and deserialization for one of my structs. I'm going by this example.
This is the struct and the relevant types:
typedef std::uint32_t vertex_key;
typedef std::uint64_t…
corazza
- 31,222
- 37
- 115
- 186
3
votes
1 answer
I would like to parse a boost::beast::flat_buffer with msgpack data using nlohmann:json
So I am using boost::beast as a WebSocket server.
I would like to receive a binary message and parse it using nlohmann::json.
However I get an error message:
none of the 3 overloads can convert parameter "nlohmann::detail::input_adapter"
Here is…
Ray Hulha
- 10,701
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- 53