How to access array elements inside JSON in nlohman json in c++? - c++

Question

I have following JSON file
{
"list" :
{
"type" : "school",
"students" : [
{
"name" : "root",
"marks" : "100"
},
{
"name" : "joe",
"version" : "100"
}]
}
}
So in code I have parsed this JSON file and assigned this JSON object to JSON::student. So I am able to assign first element to string like this :
std::string type = student["list"]["type"];
and it works. SO similarly I want to do for "name" and "marks" in "students" array. How can I do that?

Answer 1

You can simply iterate over all the elements with iterators
std::string const str = "{ \"list\" : { \"type\" : \"school\", \"students\" : [ "
"{ \"name\" : \"root\", \"marks\" : \"100\"}, "
"{ \"name\" : \"joe\", \"version\" : \"100\" } "
"] } }";
nlohmann::json const js = nlohmann::json::parse(str);
nlohmann::json const& ja = js["list"]["students"];
for (auto it = ja.begin(); it != ja.end(); ++it) {
// For each individual element (root, joe, ...)
if (it->contains("name")) {
std::string const name = (*it)["name"].get<std::string>();
// Do something with the name
}
if (it->contains("marks")) {
std::string const marks = (*it)["marks"].get<std::string>();
// Do something with the marks
}
if (it->contains("version")) {
std::string const version = (*it)["version"].get<std::string>();
// Process version
}
// ...
}