Save function in Qt Example

[A Former User]

Hi,

i use the Qt Example "Item Model Example".
When i change the values of the QTableWidget, the Bars are changing too. That's good.

How can i save the values and the 3D Bars and open that? Because when i change the values i want to save this and for example open the file in school for a presentation...

Thanks,
Henrik

[SGaist]

Hi,

Do you mean save the state of the model and reload it ?

[A Former User]

Yes + the TableWidget

[SGaist]

Then that's something you'll have to implement by hand. One possibility is to add a function to dump its content in a text file (e.g. csv) and reload it from there.

What exact example are you hacking on ?

[VRonin]

Disclaimer: this is NOT in any way a generic way to serialise (save) a model but it should work for you. It saves only the Qt::DisplayRole of a table model (no child in any index) in a csv file (readable by excel and LibreOffice calc)

#include <QAbstractItemModel>
#include <QSaveFile>
#include <QFile>
#include <QTextStream>
bool saveToCsv(const QAbstractItemModel* const model, const QString& destinationPath, const QChar& separator=','){
    if(!model){
        //Null model
        return false;
    }
    if(separator.isNull()){
        // invalid separator
        return false;
    }
    QSaveFile destinationFile(destinationPath);
    if(!destinationFile.open(QIODevice::WriteOnly | QIODevice::Text)){
        //invalid destination
        return false;
    }
    QTextStream out(&destinationFile);
    for(int i=0;i<model->rowCount();++i){
        for(int j=0;j<model->columnCount();++j){
            if(j>0)
                out << separator;
            out << model->index(i,j).data().toString();
        }
        out << '\n';
    }
    return  destinationFile.commit();
}
bool loadFromCsv(QAbstractItemModel* const model, const QString& sourcePath, const QChar& separator=','){
    if(!model){
        //Null model
        return false;
    }
    if(separator.isNull()){
        // invalid separator
        return false;
    }
    QFile sourceFile(sourcePath);
    if(!sourceFile.open(QIODevice::ReadOnly | QIODevice::Text)){
        //invalid source
        return false;
    }
    QTextStream in(&sourceFile);
    model->removeColumns(0,model->columnCount());
    model->removeRows(0,model->rowCount());
    QStringList lineParts;
    QString tempLine;
    while (in.readLineInto(&tempLine)) {
        lineParts=tempLine.split(separator,QString::KeepEmptyParts);
        if(model->columnCount()==0)
            model->insertColumns(0,lineParts.size());
        else if(model->columnCount()!=lineParts.size()){
            // different rows have different number of columns
            return false;
        }
        const int newRow= model->rowCount();
        model->insertRow(newRow);
        for(int i=0;i<lineParts.size();++i)
            model->setData(model->index(newRow,i),lineParts.at(i));
    }
    return true;
}

You can call this using something like saveToCsv(m_tableWidget->model(),"saved.csv"); and loadFromCsv(m_tableWidget->model(),"saved.csv");

[A Former User]

Thanks.
Can you give me an Example with an SaveFile Dialog and OpenFileDialog which i an use in my Project?

Henrik

[VRonin]

saveToCsv(m_tableWidget->model(),
QFileDialog::getSaveFileName(this,tr("Save to csv"),QString(),tr("Comma separated values (*.csv)"))
);
loadFromCsv(m_tableWidget->model(),
QFileDialog::getOpenFileName(this, tr("Open csv"),QString(),tr("Comma separated values (*.csv)"))
);