I am getting the below error when reading the values using BOOST_FOREACH:
Unhandled exception at 0x76FCB502 in JSONSampleApp.exe: Microsoft C++ exception: boost::wrapexcept<boost::property_tree::ptree_bad_path> at memory location 0x00CFEB18.
Could someone help me how to read values from the array with the below JSON format?
#include <string>
#include <iostream>
#include <boost/property_tree/json_parser.hpp>
#include <boost/foreach.hpp>
using namespace std;
using boost::property_tree::ptree;
int main()
{
const char* f_strSetting = R"({"Class": [{"Student": {"Name":"John","Course":"C++"}}]})";
boost::property_tree::ptree pt1;
std::istringstream l_issJson(f_strSetting);
boost::property_tree::read_json(l_issJson, pt1);
BOOST_FOREACH(boost::property_tree::ptree::value_type & v, pt1.get_child("Class.Student"))
{
std::string l_strName;
std::string l_strCourse;
l_strName = v.second.get <std::string>("Name");
l_strCourse = v.second.get <std::string>("Course");
cout << l_strName << "\n";
cout << l_strCourse << "\n";
}
return 0;
}
You asked a very similar question yesterday. We told you not to abuse a property tree library to parse JSON. I even anticipated:
Here's how you'd expand from that answer to parse the entire array into a vector at once:
#include <boost/json.hpp>
#include <boost/json/src.hpp> // for header-only
#include <iostream>
#include <string>
namespace json = boost::json;
struct Student {
std::string name, course;
friend Student tag_invoke(json::value_to_tag<Student>, json::value const& v) {
std::cerr << "DEBUG: " << v << "\n";
auto const& s = v.at("Student");
return {
value_to<std::string>(s.at("Name")),
value_to<std::string>(s.at("Course")),
};
}
};
using Class = std::vector<Student>;
int main()
{
auto doc = json::parse(R"({ "Class": [
{ "Student": { "Name": "John", "Course": "C++" } },
{ "Student": { "Name": "Carla", "Course": "Cobol" } }
]
})");
auto c = value_to<Class>(doc.at("Class"));
for (Student const& s : c)
std::cout << "Name: " << s.name << ", Course: " << s.course << "\n";
}
Printing
Name: John, Course: C++
Name: Carla, Course: Cobol
I even threw in a handy debug line in case you need to help figuring out exactly what you get at some point:
DEBUG: {"Student":{"Name":"John","Course":"C++"}}
DEBUG: {"Student":{"Name":"Carla","Course":"Cobol"}}