QIODevice::read : device not open - json

Question

I finally found a path file QFile would accept using QFile.exist() and a healthy dose of trial and error.
I want to know why the following works:
#include <QFile>
#include <QByteArray>
#include <QJsonObject>
#include <QJsonDocument>
QString path = QDir::currentPath(); // Get current dir
path.append("/noteLibrary.json");
QFile file(path); // Give QFile current dir + path to file
if (!file.exists()) { // Check to see if QFile found the file at given file_path
qDebug() << "NO FILE HERE";
}
qDebug() << path; // See what path was finally successful
file.open(QIODevice::ReadOnly); // Continue parsing document to confirm everything else is functioning normally.
QByteArray rawData = file.readAll();
// Parse document
QJsonDocument doc(QJsonDocument::fromJson(rawData));
// Get JSON object
QJsonObject json = doc.object();
// Access properties
qDebug() << json["die"].toString(); // Should output "280C4"
Successful output:
"/home/pi/noteLibrary.json"
"280C4"
But the following does NOT work:
#include <QFile>
#include <QByteArray>
#include <QJsonObject>
#include <QJsonDocument>
QFile file("/home/pi/noteLibrary.json"); // Give QFile current dir + path to file
if (!file.exists()) { // Check to see if QFile found the file at given file_path
qDebug() << "NO FILE HERE";
}
//qDebug() << path; // See what path was finally successful
file.open(QIODevice::ReadOnly); // Continue parsing document to confirm everything else is functioning normally.
QByteArray rawData = file.readAll();
// Parse document
QJsonDocument doc(QJsonDocument::fromJson(rawData));
// Get JSON object
QJsonObject json = doc.object();
// Access properties
qDebug() << json["die"].toString(); // Should output "280C4"
Error output:
NO FILE HERE
QIODevice::read (QFile, "/home/pi/Desktop/noteLibrary.json"): device not open
""
Why would QFile treat these differently? Is this a QString format issue? Or is the fact that I'm deploying this remotely to a Raspberry Pi 3 possibly to blame?

Answer 1

Regardless of what was wrong with my code above, with the below code giving QFile the absolute path does work equally to creating a QString with currentPath(). I must have had something else wrong, my mistake!
noteLibrary.json
{"note": [{
"profile": "C4",
"die": "280C4",
"pressure": 800,
"position": 10000
},
{
"profile": "CC4",
"die": "2280C4",
"pressure": 8800,
"position": 110000
}
],
"test": {
"profile": "CCC4",
"die": "22280C4",
"pressure": 88800,
"position": 1110000
}
}
main.cpp excerpt
QFile file("/home/pi/noteLibrary.json");
if (!file.exists()) qDebug() << "NO FILE FOUND";
file.open(QIODevice::ReadOnly);
QByteArray rawData = file.readAll();
QJsonDocument doc(QJsonDocument::fromJson(rawData)); // Parse document
QJsonObject jObj = doc.object(); // Get JSON object
qDebug() << jObj["test"];
Application Output
QJsonValue(object,QJsonObject({"die":"22280C4","position":1110000,"pressure":88800,"profile":"CCC4"}))
Seems odd that it displays property values in alphabetical order, not the order listed in the document.