JSON array with multiple values c++ - c++

Question

I have this body request example:
{
"users": [{
"userId": 123
}, {
"userId": 1234
}]
}
For the previous example I receive one std::list<UsersId>* VUsers that have my userId (in this case '123' and '1234'), create cJSON array, iterate my list and get all userId. (Note: the UsersId is one auxiliar class that I use and receive one int in constructor)
cJSON* cJsonUsers = cJSON_CreateArray();
cJSON_AddItemToObject(root, "VUsers", cJsonUsers);
std::list<UsersId>::const_iterator itUsers = VUsers->begin();
while (itUsers != VUsers->end())
{
cJSON *cJsonVNode = cJSON_CreateObject();
cJSON_AddItemToArray(cJsonUsers, cJsonUser);
cJSON_AddNumberToObject(cJsonUser, "userId", itUsers->userId);
++itVNodes;
}
But know I want to the same but make more simple/easy and need to change the body request to something like this:
{
"users": {
"userId": [123, 1234]
}
}
I'm using this c++ library -> https://github.com/DaveGamble/cJSON but I dont understand how to do to implement the modification that I need.
EDIT 2 (PARSE THE JSON)
cJSON* cJsonUsers = cJSON_GetObjectItem(root, "users");
if (!cJsonUsers) return 0;
if (cJsonUsers->type != cJSON_Array) return 0;
std::list<VUserId>* users = new std::list<VUserId>();
cJSON* cJsonVUser;
cJSON_ArrayForEach(cJsonVUser, cJsonUsers)
{
cJSON* cJsonVUserId = cJSON_GetObjectItem(cJsonVUser, "userId");
if (!cJsonVUserId) continue;
int user_id = cJsonVUserId->valueint;
VUserId userId(user_id);
users->push_back(userId);
}

Answer 1

Something like this could work, that is, create the object and array outside of the loop, and insert the numbers inside the loop:
cJSON* cJsonUsers = cJSON_CreateObject();
cJSON_AddItemToObject(root, "users", cJsonUsers);
cJSON* cJsonUserId = cJSON_CreateArray();
cJSON_AddItemToObject(cJsonUsers, "userId", cJsonUserId);
std::list<UsersId>::const_iterator itUsers = VUsers->begin();
while (itUsers != VUsers->end())
{
cJSON_AddItemToArray(cJsonUserId, cJSON_CreateNumber(itUsers->userId));
++itVNodes;
}
Note that there are languages out there that are more convenient to manipulate JSON if you have the flexibility (disclaimer: I was involved in the design of some of these). Of course there are always use cases when you have to use C++ and in which a library makes a lot of sense.
With languages such as C++ or Java, there is an impedance mismatch between objects in the classical sense, and data formats like XML or JSON. For example, with the standardized, declarative and functional XQuery 3.1 this does not need much code to transform the first document into the second:
let $original-document := json-doc("users.json")
return map {
"users" : map {
"userId" : array { $original-document?users?*?userId }
}
}