Converting JSON text file back to QJsonArray - c++

Question

I have an object that I serialize it into JSON using the code below (also see the the struct):
struct RegisterItem {
RegisterType Type = RegisterType::ReadWrite;
QString Name = QStringLiteral("REGISTER");
int Bank = 0;
int Address = 0;
int Range = 1;
int DefaultValue = 0;
int CurrentValue = 0;
int SpecialAction = REG_SPECIAL_ACTION_NONE;
};
This code converts it to json text file:
bool saveRegisterStateToFile(const QVector<RegisterWidget*>& widgets)
{
QJsonArray arr;
for(int i = 0; i < widgets.size(); i++) {
RegisterItem item = widgets[i]->registerItem();
auto data = QJsonObject({
qMakePair(QString("Address"), QJsonValue(item.Address)),
qMakePair(QString("Name"), QJsonValue(item.Name)),
qMakePair(QString("Bank"), QJsonValue(item.Bank)),
qMakePair(QString("Type"), QJsonValue(static_cast<int>(item.Type))),
qMakePair(QString("DefaultValue"), QJsonValue(item.DefaultValue)),
qMakePair(QString("SpecialAction"), QJsonValue(item.SpecialAction))
});
arr.push_back(data);
}
QFile file("json.txt");
file.open(QFile::WriteOnly);
file.write(QJsonDocument(arr).toJson());
}
This all works fine and produces the json file...it looks like this (first few lines):
[
{
"Address": 0,
"Bank": 0,
"DefaultValue": 0,
"Name": "V_ADC_IN",
"SpecialAction": 0,
"Type": 3
},
{
"Address": 1,
"Bank": 0,
"DefaultValue": 0,
"Name": "V_ADC_SCALE",
"SpecialAction": 0,
"Type": 3
},
{
"Address": 2,
"Bank": 0,
Now, I need to do the reverse...but my json object size is always 0! what is the problem?
QFile file(url);
file.open(QIODevice::ReadOnly | QIODevice::Text);
QString raw = file.readAll();
file.close();
QJsonDocument doc = QJsonDocument::fromJson(raw.toUtf8());
QJsonObject obj = doc.object();
QJsonArray arr = obj[""].toArray();

Answer 1

Your objects does not have an identifier...so you need to access by position in the array. Something like this:
QJsonDocument doc = QJsonDocument::fromJson(raw.toUtf8());
QJsonArray arr = doc.array(); // get array representation of the doc
for(int i = 0; i < arr.size(); i++) {
QJsonValue val = arr.at(i);
// The following line should thoritically prin the Name field
qDebug() << val.toObject().value("Name");
}