So im trying to create a json Object in c++ dynamically. I want to add a timestamp and then an array with the data included.
So thats what my json String would look like :
{
"timestep": "2160.00",
"vehicles": [
{
"id": "35092_35092_353",
"x": "6.988270",
"y": "50.872139",
"angle": "-20.812787",
"type": "passenger_P_14_1",
"speed": "0.000000",
"pos": "4.600000",
"lane": "4.600000",
"slope": "4.600000"
},
{
"id": "35092_35092_353",
"x": "6.988270",
"y": "50.872139",
"angle": "-20.812787",
"type": "passenger_P_14_1",
"speed": "0.000000",
"pos": "4.600000",
"lane": "4.600000",
"slope": "4.600000"
},
{
"id": "35092_35092_353",
"x": "6.988270",
"y": "50.872139",
"angle": "-20.812787",
"type": "passenger_P_14_1",
"speed": "0.000000",
"pos": "4.600000",
"lane": "4.600000",
"slope": "4.600000"
}
]
}
Im totally new to C++ and im using the Casablanca ( C++ REST SDK) package. So im having a really hard time producing the code. And i cant find any working solutions. I found this on the wiki
Create a JSON object:
json::value obj;
obj[L"key1"] = json::value::boolean(false);
obj[L"key2"] = json::value::number(44);
obj[L"key3"] = json::value::number(43.6);
obj[L"key4"] = json::value::string(U("str"));
and that works for me. But how do i create an array?
i tried several things but nothing worked. Maybe theres a better package? But as far as i understood its an official micorosft package for json and http.
Help would be really nice!
There are 2 mechanisms. If you are used to std c++ libraries, this should look familiar. Element vector is derived from std::vector.
json::value::element_vector e;
// the first item in the pair is the array index, the second the value
e.push_back(std::make_pair(json::value(0), json::value(false)));
e.push_back(std::make_pair(json::value(1), json::value::string(U("hello"))));
json::value arr(e);
And, if you prefer a cleaner look, and can accept a less efficient compiled result:
json::value arr;
arr[0] = json::value(false);
arr[1] = json::value(U("hello"));
From your message you have tried a bunch of stuff. If you have tried mechanisms like these but they didn't work, give us a sample program that demontrates the failure and we'll have a crack at it.
To get the basic structure in your file above:
json::value vehicles;
vehicles[0] = // 1st vehicle object
vehicles[1] = // 2nd vehicle object
// etc
json::value root;
root[L"timestep"] = json::number(2160.0);
root[L"vehicles"] = vehicles;
Here is another method to produce a json array in Casablanca:
int size = 3;
web::json::value yourJson;
yourJson[U("vehicles")] = web::json::value::array(size);
yourJson[U("vehicles")].as_array()[0] = web::json::value(U("some entry"));
yourJson[U("vehicles")].as_array()[1] = web::json::value(U("another entry"));
//...
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