Problem with saving function (overwrite file which saved by dialog)

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@Wieland

QFSFileEngine::open: No file name specified
"Fehler beim Speichern der Datei: "
QIODevice::write (QFile, ""): device not open

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@HenrikSt. Congrats, you just found your problem, fileName is empty :-)

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That good, i know..

But i don't know how to fix.
If you help me I am very happy :-)

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You must assign some useful value to fileName, e.g. like this:

void MainWindow::mySaveFunction()
{
    const QString path = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
    QFile file;
    fileName = QString("%1/%2").arg(path).arg("unbenannt.html");
    file.setFileName(fileName);

    if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
    {
        qDebug() << QString("Fehler beim Speichern der Datei: %1").arg(fileName);
    }

    QTextStream out(&file);
    out << toHtml();
    file.close();
}

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@Wieland
Hi, this works, but the Problem is, that you create a new file ("unbenannt.html")

I want to overwrite the file i create with the Dialog before. You understand?

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@HenrikSt. In this case the name you assign to fileName here must exactly match the name of the existing file.

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@Wieland
I know... But every user enter another fileName so "unbenannt.htm" will not work..

Do you have another idea?

Thanks :)

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@HenrikSt. After the user entered the file name the first time, just save the name then and use it again later.

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@Wieland
Ah ok. I'm new in Qt. Can you write an example for this case that i can use it?

I have Problems with writing Code. Reading is no Problem. Do you have any tips for me?

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The following code isn't very elegant but I think it's good enough to serve as an example.

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    bool mySaveFunction();
    QString toHtml() const;

private slots:
    void saveFile();

private:
    Ui::MainWindow *ui;
    QString m_fileName;

};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QFile>
#include <QTextStream>
#include <QDebug>
#include <QStandardPaths>
#include <QFileDialog>
#include <QMessageBox>

bool MainWindow::mySaveFunction()
{
    // if this happens we have a bug in our code
    Q_ASSERT_X(!m_fileName.isEmpty(), "mySaveFunction", "m_fileName is empty");

    QFile file(m_fileName);
    if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
    {
        QMessageBox::critical(this, "Fehler", QString("Fehler beim Speichern der Datei: %1").arg(m_fileName) );
        return false;
    }
    QTextStream out(&file);
    out << toHtml();
    file.close();
    QMessageBox::information(this, "Information", QString("Die Datei wurde gespeichert: %1").arg(m_fileName) );
    return true;
}


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    connect(ui->pushButton, SIGNAL(clicked(bool)), this, SLOT(saveFile()));
}

MainWindow::~MainWindow()
{
    delete ui;
}

QString MainWindow::toHtml() const
{
    return "<html></html>\n";
}

void MainWindow::saveFile()
{
    if (m_fileName.isEmpty()) {
        // first attempt to save the file
        m_fileName = QFileDialog::getSaveFileName(this, tr("Speichern unter..."),
                                        QString("Unbenannt.htm"), tr("TextPad 1.0 (*.htm);;"));
        if (m_fileName.isEmpty()) {
            return; // dialog was canceled
        }
    }
    if (!mySaveFunction()) {
        m_fileName.clear(); // saving failed. clear m_fileName so the QFileDialog will come up again next time
    }
}

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@Wieland
Hi, thank you for the example

if (!mySaveFunction()) {
        m_fileName.clear(); // saving failed. clear m_fileName so the QFileDialog will come up again next time
    }

This Code is not working...

C:\Users\Henrik\Documents\TextPad\pagestextedit.cpp:557: Fehler: could not convert 'PagesTextEdit::saveUnderDocument()' from 'void' to 'bool'
             if (!saveUnderDocument()) {
                                    ^

I have void MainWindow::save....
and not bool

How can i Change it?

One Problem is existing..
When i open a file e.g. from Desktop and i write something in and want to save it with mySaveFunction i get an runtime error...
Do you know why?

Thanks a lot

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@HenrikSt.
The Code which is not working i fixed it...

But the other Problem not

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@HenrikSt. said:

Do you know why?

No.

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@Wieland
https://onedrive.live.com/redir?resid=8CA2253BB1C9EA6!60243&authkey=!ABJFjbW9wpRomkw&v=3&ithint=photo%2Cpng

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@HenrikSt.
But you understand my Problem?

jsulm

The cause for that crash can be everything!
How should anybody know what it is without your code?
Did you try to debug your program to see where it crashes?