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json/json.cpp Source File
#include <cppcms/json.h>
#include <iostream>
#include <sstream>
struct person {
std::string name;
double salary;
std::vector<std::string> kids_names;
};
namespace cppcms {
namespace json {
//
// We specilize cppcms::json::traits structure to convert
// objects to and from json values
//
template<>
struct traits<person> {
// this function should throw
// cppcms::json::bad_value_cast in case
// of invalid or impossible conversion,
// this would give an easy way to substitute
// a default value in case of fault
static person get(value const &v)
{
person p;
if(v.type()!=is_object)
throw bad_value_cast();
p.name=v.get<std::string>("name");
p.salary=v.get<double>("salary");
p.kids_names=
v.get<std::vector<std::string> >("kids_names");
// this works because generic vector and string specialized
return p;
}
static void set(value &v,person const &in)
{
v.set("name",in.name);
v.set("salary",in.salary);
v.set("kids_names",in.kids_names);
}
};
} // json
} // cppcms
int main()
{
cppcms::json::value my_object;
// Create object data
my_object["name"]="Moshe";
my_object["salary"]=1000.0;
my_object["kids_names"][0]="Yossi";
my_object["kids_names"][1]="Yonni";
// this is additional data
my_object["data"]["weight"]=85;
my_object["data"]["height"]=1.80;
// Get values using path.
std::string name=my_object.get<std::string>("name");
double salary = my_object.get<double>("salary");
int weight = my_object.get<int>("data.weight");
double height = my_object.get<double>("data.height");
// get values using default value if not set
std::string eyes_color = my_object.get("data.eyes_color","brown");
// load person object from the object
// using above traits
person moshe = my_object.get_value<person>();
// save person object to json object
cppcms::json::value other = moshe;
// write data to output
std::cout << other << std::endl;
// write data formatter nicely
my_object.save(std::cout,cppcms::json::readable);
// save object to stream and load it back
std::stringstream tmp;
tmp << my_object;
cppcms::json::value reloaded;
reloaded.load(tmp,true);
}
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