Rapid json, c++, json, modify empty json array

Question

I have a json file, which contains two object. The first object is an array of objects. Each of these objects has an element "key" and empty array. I need to fill the array with 4 numbers and I need to save back the json. I am checking the tutorial, but probably I am missing something. May somebody help me please? Here is my code, that doesn't work:

void BimObjectsToProjection::modifyViewBoxForProjection(std::string projectionName, long long minX, long long minY, long long Xlen, long long Ylen)
{
    Value& projections = md_FilesJsonDocument["ProjectionImages"];
    for (Value::ValueIterator projectionsIterator = projections.Begin(); projectionsIterator != projections.End(); ++projectionsIterator)
    {
        rapidjson::Value& projectionJson = *projectionsIterator;
        string name = projectionJson["Name"].GetString();
        if (projectionName == name)
        {
            Document::AllocatorType& allocator = md_FilesJsonDocument.GetAllocator();
            rapidjson::Value& viewBox = (*projectionsIterator)["BB"];

            viewBox.PushBack((int)minX, allocator);
            viewBox.PushBack((int)minY, allocator);
            viewBox.PushBack((int)Xlen, allocator);
            viewBox.PushBack((int)Ylen, allocator);
           
            rapidjson::StringBuffer strbuf;
            rapidjson::Writer<rapidjson::StringBuffer> writer(strbuf);
            md_FilesJsonDocument.Accept(writer);
            break;
        }
    }
}

The json looks like this:

{
    "ProjectionImages": [
        {
            "Id": "33c75d31-7ccd-4daf-814a-56250cdee42f",
            "Name": "Projection_Image_Architectural_First Floor_Zone 1.png",
            "Discipline": "Architectural",
            "LevelName": "First Floor",
            "BB": [],
            "SheetFileName": null,
            "ProjectionLineFileId": "36bb6683-c6d3-43c2-bbdc-aedf3203ea86",
            "ProjectionLineFileName": "Projection_Image_Architectural_First Floor_Zone 1.pdf",
            "ZoneName": "Zone 1"
        },
...

Even if I try to add new array member, this code doesn't work. Is it because of my writing approch?

void BimObjectsToProjection::modifyViewBoxForProjection(std::string projectionName, long long minX, long long minY, long long Xlen, long long Ylen)
{
    Value& projections = md_FilesJsonDocument["ProjectionImages"];
    for (Value::ValueIterator projectionsIterator = projections.Begin(); projectionsIterator != projections.End(); ++projectionsIterator)
    {
        rapidjson::Value& projectionJson = *projectionsIterator;
        string name = projectionJson["Name"].GetString();
        if (projectionName == name)
        {
            Document::AllocatorType& allocator = md_FilesJsonDocument.GetAllocator();
           
            Value a(kArrayType);
            a.PushBack((int)minX, allocator);
            a.PushBack((int)minY, allocator);
            a.PushBack((int)Xlen, allocator);
            a.PushBack((int)Ylen, allocator);
            (*projectionsIterator).AddMember("AA", a, allocator);
                  
            rapidjson::StringBuffer strbuf;
            rapidjson::Writer<rapidjson::StringBuffer> writer(strbuf);
            md_FilesJsonDocument.Accept(writer);
            break;
        }
    }
}

Answer 1

This part of the code doesn't do anything:

rapidjson::StringBuffer strbuf;
rapidjson::Writer<rapidjson::StringBuffer> writer(strbuf);
md_FilesJsonDocument.Accept(writer);

strbuf contains the json string but it is discarded. I would move this into a separate function and print the conents with std::cout << strbuf;.

To write directly to a file:

std::ofstream ofs("out.json", std::ios::out);
if (ofs.is_open()) {
    rapidjson::OStreamWrapper osw(ofs);
    rapidjson::Writer<rapidjson::OStreamWrapper> writer(osw);
    md_FilesJsonDocument.Accept(writer);
}