Write nested arrays with rapidjson the "SAX" way

Question

I'm trying to write a json structure using rapidjson the sax way. Here's what I do:

  StringBuffer sb;
  PrettyWriter<StringBuffer> writer(sb);
  writer.StartObject();

  writer.Key("user");
  writer.StartArray();

  OperatorAcPtrList::iterator xIt;
  for (xIt = userList.begin(); xIt != userList.end(); xIt++)
  {
    writer.Key("userId");
    writer.Uint((*xIt)->id);

    writer.Key("productIdList");
    writer.StartArray();

    ProductIdList::iterator xPrdIdIt;
    for (xPrdIdIt = ((*xIt)->productList).begin(); 
        xPrdIdIt != ((*xIt)->productList).end(); xPrdIdIt++)
    {
      writer.Uint(*xPrdIdIt);
    }
    writer.EndArray();
  }
  writer.EndArray();
  writer.EndObject();

But the result is not what I'd expect, it's:

{
    "userList": [
        "userId", 
        20,
        "productIdList",
        [
           1,
           2
        ],
        "userId",
        21,
        "productIdList",
        [
           1,
           2
        ]
    ]
}

It looks like everything inside the first StartArray EndArray becomes an array element. What I'd like to obtain instead is:

{
    "userList": [
        {
            "userId" : 20,
            "productIdList" : [1, 2],
        },
        {
            "userId" : 21,
            "productIdList" : [1, 2]
        }
    ]
}

Am I doing something wrong or what I want is not supported at all?

Answer 1

Before you call writer.Key("userId"); in the for loop, add writer.StartObject();, and add writer.EndObject(); correspondingly. Here is an example:

#include "rapidjson/writer.h"
#include "rapidjson/stringbuffer.h"
#include <iostream>

using namespace rapidjson;
using namespace std;

int main() {
    StringBuffer s;
    Writer<StringBuffer> writer(s);
    writer.StartObject();

    writer.Key("userList");
    writer.StartArray();

    writer.StartObject();
    writer.Key("userId");
    writer.Uint(20);
    writer.Key("productIdList");
    writer.StartArray();
    for (unsigned i = 1; i < 3; i++)
        writer.Uint(i);
    writer.EndArray();
    writer.EndObject();

    writer.StartObject();
    writer.Key("userId");
    writer.Uint(21);
    writer.Key("productIdList");
    writer.StartArray();
    for (unsigned i = 1; i < 3; i++)
        writer.Uint(i);
    writer.EndArray();
    writer.EndObject();

    writer.EndArray();
    writer.EndObject();
    cout << s.GetString() << endl;
}