Unable to copy a file from one directory to another

[ejoshva]

I am trying to copy a file from one directory to another

Tried QFile::copy(). The file is copied but the size is zero Kb

Tried placing a dummy file and then replacing with original

But still the size is 0 Kb.

QDir qd;
    QFile srcfile;
    QFile destifile;
 
    QString dbsrcfilepath = qd.currentPath().append("/learnOn1.sqlite");
    dbsrcfilepath = QDir::toNativeSeparators(dbsrcfilepath);
 //   dbsrcfilepath :  "/Users/user/build-learnOn-Desktop_Qt_5_4_0_clang_64bit-Debug/learnOn.app/Contents/MacOS/learnOn1.sqlite"
    QString libpath = qd.homePath() + QDir::separator()+"learnOnContent" + QDir::separator();
    if(!(QDir(libpath).exists()))
        QDir().mkdir(libpath);
    QString dbdestinationfilepath = libpath.append("learnOn.sqlite");
 //dbdestinationfilepath :  "/Users/user/learnOnContent/learnOn.sqlite"
 
    dbdestinationfilepath = QDir::toNativeSeparators(dbdestinationfilepath);
 
    srcfile.setFileName(dbdestinationfilepath);
    destifile.setFileName(dbsrcfilepath);
    if(!srcfile.exists())
    {       
        bool success = true;
        success &= destifile.open( QFile::ReadOnly );
        success &= srcfile.open( QFile::WriteOnly | QFile::Truncate );
        qDebug()<<destifile.readAll().length();
        success &= srcfile.write( destifile.readAll() ) >= 0;
        destifile.close();
        srcfile.close();
    }
    else
    {
        srcfile.copy(dbdestinationfilepath);
    }

QDir qd;
    QFile srcfile;
    QFile destifile;

    QString dbsrcfilepath = qd.currentPath().append("/learnOn1.sqlite");
    dbsrcfilepath = QDir::toNativeSeparators(dbsrcfilepath);
 //   dbsrcfilepath :  "/Users/user/build-learnOn-Desktop_Qt_5_4_0_clang_64bit-Debug/learnOn.app/Contents/MacOS/learnOn1.sqlite"
    QString libpath = qd.homePath() + QDir::separator()+"learnOnContent" + QDir::separator();
    if(!(QDir(libpath).exists()))
        QDir().mkdir(libpath);
    QString dbdestinationfilepath = libpath.append("learnOn.sqlite");
 //dbdestinationfilepath :  "/Users/user/learnOnContent/learnOn.sqlite"
   
    dbdestinationfilepath = QDir::toNativeSeparators(dbdestinationfilepath);

    srcfile.setFileName(dbdestinationfilepath);
    destifile.setFileName(dbsrcfilepath);
    if(!srcfile.exists())
    {       
        bool success = true;
        success &= destifile.open( QFile::ReadOnly );
        success &= srcfile.open( QFile::WriteOnly | QFile::Truncate );
        qDebug()<<destifile.readAll().length();
        success &= srcfile.write( destifile.readAll() ) >= 0;
        destifile.close();
        srcfile.close();
    }
    else
    {
        srcfile.copy(dbdestinationfilepath);
    }

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The copy is not proper. File size is always 0.

Kindly help to resolve this issue.

Thanks in advance

[wysota]

Please provide a minimal compilable example reproducing the problem.

[ejoshva]

#include "mainwindow.h"
#include <QApplication>
#include <QDir>
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    QDir qd;
    QFile srcfile;
    QFile destifile;
 
    QString dbsrcfilepath = "/Users/user/build-learnOn-Desktop_Qt_5_4_0_clang_64bit-Debug/learnOn.app/Contents/MacOS/learnOn1.sqlite";
    dbsrcfilepath = QDir::toNativeSeparators(dbsrcfilepath);
    destifile.setFileName(dbsrcfilepath);
    if(!(QDir("/Users/user/learnOnContent/").exists()))
        QDir().mkdir("/Users/user/learnOnContent/");
 
    QString dbdestinationfilepath = "/Users/user/learnOnContent/learnOn.sqlite";
    dbdestinationfilepath = QDir::toNativeSeparators(dbdestinationfilepath);
    srcfile.setFileName(dbdestinationfilepath);
 
    if(!srcfile.exists())
    {
        bool success = true;
        success &= destifile.open( QFile::ReadOnly );
        success &= srcfile.open( QFile::WriteOnly | QFile::Truncate );
 
        success &= srcfile.write( destifile.readAll() ) >= 0;
        destifile.close();
        srcfile.close();
    }
    else
    {
        srcfile.copy(dbdestinationfilepath);
    }
 
    return a.exec();
}

#include "mainwindow.h"
#include <QApplication>
#include <QDir>
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QDir qd;
    QFile srcfile;
    QFile destifile;

    QString dbsrcfilepath = "/Users/user/build-learnOn-Desktop_Qt_5_4_0_clang_64bit-Debug/learnOn.app/Contents/MacOS/learnOn1.sqlite";
    dbsrcfilepath = QDir::toNativeSeparators(dbsrcfilepath);
    destifile.setFileName(dbsrcfilepath);
    if(!(QDir("/Users/user/learnOnContent/").exists()))
        QDir().mkdir("/Users/user/learnOnContent/");

    QString dbdestinationfilepath = "/Users/user/learnOnContent/learnOn.sqlite";
    dbdestinationfilepath = QDir::toNativeSeparators(dbdestinationfilepath);
    srcfile.setFileName(dbdestinationfilepath);

    if(!srcfile.exists())
    {
        bool success = true;
        success &= destifile.open( QFile::ReadOnly );
        success &= srcfile.open( QFile::WriteOnly | QFile::Truncate );

        success &= srcfile.write( destifile.readAll() ) >= 0;
        destifile.close();
        srcfile.close();
    }
    else
    {
        srcfile.copy(dbdestinationfilepath);
    }
    
    return a.exec();
}

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copying from dbsrcfilepath to dbdestinationfilepath

[ChrisW67]

Line 34 tries to copy srcfile, which refers to the path dbdestinationfilepath, to dbdestinationfilepath. That seems unlikely to be productive.

[ejoshva]

Thats fine, it has to be srcfile.copy(dbsrcfilepath);

Firstly if true case is not working.

[wysota]

Thats fine

Why is that fine? You cannot copy the file over itself.

[ejoshva]

What I meant was 'else' case is not the problem as it's written on the fly and I can correct it.

I wanted to resolve the issue in the if success case first.

[wysota]

What I meant was 'else' case is not the problem as it's written on the fly and I can correct it.

I wanted to resolve the issue in the if success case first.

I have no idea what you mean, sorry.

[anda_skoa]

I wanted to resolve the issue in the if success case first.

You solved that yourself then, because the "then" case does not use QFile::copy().

Cheers,
_