Fetching current json adding to it and storing it back in the file

Kris Revi

im doing something wrong here but i can't see what!! so im trying to read the json file and add to it and then store it back into the json file but for some reason it dont add/append to the current json it completely rewrites it with that 1 entry...

bool DeviceData::devicedataupdated()
{
    DeviceDataDebugger.LevelInfo("DEVICEDATA", "Adding New Device", "!");

    QFile deviceListFile(_JsonFile);

    if( !deviceListFile.open( QIODevice::ReadOnly ) )
    {
        DeviceDataDebugger.LevelError("DEVICEDATA", "Could not read the json file", "!");
        return false;
    }

    QJsonDocument jsonOrg = QJsonDocument::fromJson( deviceListFile.readAll() );

    deviceListFile.close();

    if (deviceListFile.open(QIODevice::WriteOnly | QIODevice::Text))
    {
        QJsonObject newDevice;

        newDevice.insert("IPA",      "newdevice");
        newDevice.insert("Icon",     "fa_bolt");
        newDevice.insert("Name",     "New Device");
        newDevice.insert("Status",   "online");
        newDevice.insert("Type",     "Strip");
        newDevice.insert("UVLights", "false");

        QJsonArray devices = jsonOrg.array();

        devices.push_back(newDevice);

        QJsonDocument jsonDoc( devices );

        QJsonObject obj = jsonDoc.object();

        deviceListFile.write(jsonDoc.toJson());

        deviceListFile.close();
        return true;
    }
    return false;
}

This is how it looks befor running the code above (and how it should look with the object "Device")

{
    "Device": [
        {
            "IPA": "studiolights",
            "Icon": "fa_bolt",
            "Name": "Studio Lights",
            "Status": "online",
            "Type": "Strip",
            "UVLights": "false"
        }
    ]
}

This is after

[
    {
        "IPA": "newdevice",
        "Icon": "fa_bolt",
        "Name": "New Device",
        "Status": "online",
        "Type": "Strip",
        "UVLights": "false"
    }
]

Kris Revi

The complete answer :)

bool DeviceData::devicedataupdated()
{
    QFile deviceListFile(_JsonFile);

    if( !deviceListFile.open( QIODevice::ReadOnly | QIODevice::Text ) )
    {
        return false;
    }

    QJsonDocument jsonOrg = QJsonDocument::fromJson( deviceListFile.readAll() );

    deviceListFile.close();

    if ( deviceListFile.open( QIODevice::WriteOnly | QIODevice::Text ) )
    {
        QJsonObject newDevice;

        newDevice.insert( "IPA",      "newdevice" );
        newDevice.insert( "Icon",     "fa_bolt" );
        newDevice.insert( "Name",     "New Device" );
        newDevice.insert( "Status",   "online" );
        newDevice.insert( "Type",     "Strip" );
        newDevice.insert( "UVLights", "false" );

        auto top = jsonOrg.object();

        auto devices = top.value( "Device" ).toArray();

        devices.push_back( newDevice );

        top.insert("Device", devices);

        QJsonDocument jsonDoc( top );

        deviceListFile.write( jsonDoc.toJson() );

        deviceListFile.close();
        return true;
    }

    return false;
}

sierdzio

@Kris-Revi said in Fetching current json adding to it and storing it back in the file:

if( !deviceListFile.open( QIODevice::ReadOnly ) )
{

You are opening the file without text mode.

if( !deviceListFile.open( QFile::ReadOnly | QFile::Text ) )

QJsonArray devices = jsonOrg.array();

Add a log here (or look it up in debugging session) to see if there is actually any data read from the file.

Kris Revi

@sierdzio wait QFile::ReadOnly & QFile::Text i thought it was QIODevice::ReadOnly and QIODevice::Text

sierdzio

@Kris-Revi said in Fetching current json adding to it and storing it back in the file:

@sierdzio wait QFile::ReadOnly & QFile::Text i thought it was QIODevice::ReadOnly and QIODevice::Text

Doesn't matter it's the same enum and the values are the same. I prefer using QFile because it's shorter and more consistent.

Kris Revi

@sierdzio said in Fetching current json adding to it and storing it back in the file:

QJsonArray devices = jsonOrg.array();

Add a log here (or look it up in debugging session) to see if there is actually any data read from the file.

hmmm the print out comes up empty :S infact it does not print at all

        for(int i = 0; i < devices.size(); i++)
            qDebug() << "Json Original : " << devices[i];

sierdzio

Then at least we know the problem lies in file reading, not in saving.

Check what readAll() actually returns. Plus add error checking to JSON document (add and check QJsonParseError to your fromJson() call).

Kris Revi

@sierdzio

qDebug() << "File Readl All : " << deviceListFile.readAll();
qDebug() << "Error : " << error->errorString() << error->offset;

File Readl All :  ""
Error :  "no error occurred" 0

it just comes up empty :S

sierdzio

OK, case clear. The file is empty :-) Verify the path, and open the file in system to see if it's true.

Kris Revi

@sierdzio i JUST did :| the file exists and has stuff in it :S

sierdzio

@Kris-Revi said in Fetching current json adding to it and storing it back in the file:

deviceListFile.readAll();

Except: make sure you call readAll() ONCE - store it in a variable, then print with qDebug(), then pass to the logic below it.

If you call it twice, the second call will likely be empty.

Kris Revi

@sierdzio so by qDebug() << "File Readl All : " << jsonOrg; i got

File Readl All :  QJsonDocument({"Device":[{"IPA":"studiolights","Icon":"fa_bolt","Name":"Studio Lights","Status":"online","Type":"Strip","UVLights":"false"}]})
Error :  "no error occurred" 0

sierdzio

Of course it clears the file but that has no consequence - you are building a new JSON will all the data in it, and then save it. So it's good that at that point the file is empty.

Kris Revi

@sierdzio so now the only part is this

    if ( deviceListFile.open( QIODevice::WriteOnly | QIODevice::Text ) )
    {
        QJsonObject newDevice;

        newDevice.insert("IPA",      "newdevice");
        newDevice.insert("Icon",     "fa_bolt");
        newDevice.insert("Name",     "New Device");
        newDevice.insert("Status",   "online");
        newDevice.insert("Type",     "Strip");
        newDevice.insert("UVLights", "false");

        QJsonArray devices = jsonOrg.array();

        devices.push_back(newDevice);

        QJsonDocument jsonDoc( devices );

        QJsonObject obj = jsonDoc.object();

        deviceListFile.write(jsonDoc.toJson());

        deviceListFile.close();
        return true;
    }

sierdzio

Hey wait. The jsonOrg is not an array! You have a top-level object there called "Device". So that's why this code is failing for you.

auto top = jsonOrg.object();
auto devices = top.value("Device").toArray();
[...]
QJsonDocument jsonDoc( top );

With that it should work.

Kris Revi

@sierdzio

    if ( deviceListFile.open( QIODevice::WriteOnly | QIODevice::Text ) )
    {
        QJsonObject newDevice; // projectDetails

        newDevice.insert("IPA",      "newdevice");
        newDevice.insert("Icon",     "fa_bolt");
        newDevice.insert("Name",     "New Device");
        newDevice.insert("Status",   "online");
        newDevice.insert("Type",     "Strip");
        newDevice.insert("UVLights", "false");

        auto top = jsonOrg.object();

        QJsonArray devices = top.value("Device").toArray();

        devices.push_back(newDevice);

        QJsonDocument jsonDoc( top );

        deviceListFile.write(jsonDoc.toJson());

        deviceListFile.close();
        return true;
    }

does nothing! like the file remains as it was :/ no new entry was added when running the code nor any error!

sierdzio

Ah sorry, it's working on a copy of the array, obviously. You need to also add devices back to top:

top.insert("Device", devices);

Kris Revi

@sierdzio there we go :)

Kris Revi

The complete answer :)

bool DeviceData::devicedataupdated()
{
    QFile deviceListFile(_JsonFile);

    if( !deviceListFile.open( QIODevice::ReadOnly | QIODevice::Text ) )
    {
        return false;
    }

    QJsonDocument jsonOrg = QJsonDocument::fromJson( deviceListFile.readAll() );

    deviceListFile.close();

    if ( deviceListFile.open( QIODevice::WriteOnly | QIODevice::Text ) )
    {
        QJsonObject newDevice;

        newDevice.insert( "IPA",      "newdevice" );
        newDevice.insert( "Icon",     "fa_bolt" );
        newDevice.insert( "Name",     "New Device" );
        newDevice.insert( "Status",   "online" );
        newDevice.insert( "Type",     "Strip" );
        newDevice.insert( "UVLights", "false" );

        auto top = jsonOrg.object();

        auto devices = top.value( "Device" ).toArray();

        devices.push_back( newDevice );

        top.insert("Device", devices);

        QJsonDocument jsonDoc( top );

        deviceListFile.write( jsonDoc.toJson() );

        deviceListFile.close();
        return true;
    }

    return false;
}