cannot share the database connection!!!!

**cbarmpar** · 23rd September 2008, 09:53

Thank you for the reply but still not aware on what should I change.

Why and where should I use the new operator?

Many thanks in advance.

**spirit** · 23rd September 2008, 09:58

in this method

Qt Code:

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void kentriko::sindesi(){
    database* d;//<<<<- here i am creating the pointer to the database class//
    d->show();
}

void kentriko::sindesi(){
    database* d;//<<<<- here i am creating the pointer to the database class//
    d->show();
}

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so, it should look like

Qt Code:

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void kentriko::sindesi(){
    database* d = new database();
    d->show();
}

void kentriko::sindesi(){
    database* d = new database();
    d->show();
}

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**cbarmpar** · 23rd September 2008, 10:01

thank you for the reply.

Shall i leave the constractor as it is?

Since d is a pointer i am not coping the object right when i do the following:

parathiro *para = new parathiro(0,d);

do i also need to change the constractor of the parathiro?

Regards.

**cbarmpar** · 23rd September 2008, 10:08

sorry forgot to add:

my implementation now looks like:

Qt Code:

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parathiro::parathiro(QWidget *parent = 0, database &d)
    : QMainWindow(parent)
{
	ui.setupUi(this);
	connect(ui.anixe, SIGNAL(clicked()) , this , SLOT(anixe()));
	connect(ui.pare, SIGNAL(clicked()) , this , SLOT(pare()));
	connect(ui.proto,SIGNAL(textChanged(const QString&)),this,SLOT(alagi()));
}
 
void parathiro::alagi(){
  QSqlQuery erotisi(*d->get_db());
  proto = sinartisi_SELECT( "onoma,epitheto" ,"onomata", "onoma", ui.proto->text());
  ui.deytero->setText(proto);
  erotisi.exec(proto);
  variant = erotisi.size();
  ui.trito->setText(variant.toString());
}

parathiro::parathiro(QWidget *parent = 0, database &d)
    : QMainWindow(parent)
{
	ui.setupUi(this);
	connect(ui.anixe, SIGNAL(clicked()) , this , SLOT(anixe()));
	connect(ui.pare, SIGNAL(clicked()) , this , SLOT(pare()));
	connect(ui.proto,SIGNAL(textChanged(const QString&)),this,SLOT(alagi()));
}

void parathiro::alagi(){
  QSqlQuery erotisi(*d->get_db());
  proto = sinartisi_SELECT( "onoma,epitheto" ,"onomata", "onoma", ui.proto->text());
  ui.deytero->setText(proto);
  erotisi.exec(proto);
  variant = erotisi.size();
  ui.trito->setText(variant.toString());
}

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and this is how i call it:

Qt Code:

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void kentriko::anixe(){
    parathiro *para = new parathiro(d);
	QMdiSubWindow *subwindow = ui.mdiArea->addSubWindow(para);
	subwindow->setAttribute(Qt::WA_DeleteOnClose);
	subwindow->resize(sizeHint());
	subwindow->show();
}
 
void kentriko::sindesi(){
	database *d = new database;
	d->show();
}

void kentriko::anixe(){
    parathiro *para = new parathiro(d);
	QMdiSubWindow *subwindow = ui.mdiArea->addSubWindow(para);
	subwindow->setAttribute(Qt::WA_DeleteOnClose);
	subwindow->resize(sizeHint());
	subwindow->show();
}

void kentriko::sindesi(){
	database *d = new database;
	d->show();
}

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regards.

**spirit** · 23rd September 2008, 10:09

of course.
so it should look like

Qt Code:

Switch view

class parathiro : public QMainWindow
{
    Q_OBJECT
public:
    parathiro(QWidget *parent = 0, database *d);

class parathiro : public QMainWindow
{
    Q_OBJECT
public:
    parathiro(QWidget *parent = 0, database *d);

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**cbarmpar** · 23rd September 2008, 10:15

still cant compile i am getting an error in the constructor of parathrio.

**spirit** · 23rd September 2008, 10:17

what kind of error do you get?

**cbarmpar** · 23rd September 2008, 10:23

in the parathiro.h:

Qt Code:

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#ifndef PARATHIRO_H
#define PARATHIRO_H
 
#include <QtGui/QMainWindow>
#include "ui_parathiro.h"
#include "../database/database.h"
database *d;
class parathiro : public QMainWindow
{
    Q_OBJECT
public:
    parathiro(QWidget *parent = 0,database *d = 0);//err= after previous specification in parathiro::parathiro(QWidget*.database*)
    ~parathiro();

#ifndef PARATHIRO_H
#define PARATHIRO_H

#include <QtGui/QMainWindow>
#include "ui_parathiro.h"
#include "../database/database.h"
database *d;
class parathiro : public QMainWindow
{
    Q_OBJECT
public:
    parathiro(QWidget *parent = 0,database *d = 0);//err= after previous specification in parathiro::parathiro(QWidget*.database*)
    ~parathiro();

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and in the parathiro.cpp:

Qt Code:

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#include "parathiro.h"
#include <iostream>
#include <QString>
#include "../diafores_sinartisis/sinartisis.h"
#include "../database/database.h"
 #include <QMainWindow>
using namespace std;
 
parathiro::parathiro(QWidget *parent = 0, database *d)//Multiple markers at this line
//	- default argument given for parameter 1 of 
//	 ‘parathiro::parathiro(QWidget*, database*)’
//	- unused parameter ‘d’
    : QMainWindow(parent)
{
	ui.setupUi(this);
	connect(ui.anixe, SIGNAL(clicked()) , this , SLOT(anixe()));
	connect(ui.pare, SIGNAL(clicked()) , this , SLOT(pare()));
	connect(ui.proto,SIGNAL(textChanged(const QString&)),this,SLOT(alagi()));
}
 
void parathiro::alagi(){
  QSqlQuery erotisi(d->get_db());// no matching function to call 'Qsqlquery::QSqlquery(QSqlDatabase)
  proto = sinartisi_SELECT( "onoma,epitheto" ,"onomata", "onoma", ui.proto->text());
  ui.deytero->setText(proto);
  erotisi.exec(proto);
  variant = erotisi.size();
  ui.trito->setText(variant.toString());
}

#include "parathiro.h"
#include <iostream>
#include <QString>
#include "../diafores_sinartisis/sinartisis.h"
#include "../database/database.h"
 #include <QMainWindow>
using namespace std;

parathiro::parathiro(QWidget *parent = 0, database *d)//Multiple markers at this line
//	- default argument given for parameter 1 of 
//	 ‘parathiro::parathiro(QWidget*, database*)’
//	- unused parameter ‘d’
    : QMainWindow(parent)
{
	ui.setupUi(this);
	connect(ui.anixe, SIGNAL(clicked()) , this , SLOT(anixe()));
	connect(ui.pare, SIGNAL(clicked()) , this , SLOT(pare()));
	connect(ui.proto,SIGNAL(textChanged(const QString&)),this,SLOT(alagi()));
}

void parathiro::alagi(){
  QSqlQuery erotisi(d->get_db());// no matching function to call 'Qsqlquery::QSqlquery(QSqlDatabase)
  proto = sinartisi_SELECT( "onoma,epitheto" ,"onomata", "onoma", ui.proto->text());
  ui.deytero->setText(proto);
  erotisi.exec(proto);
  variant = erotisi.size();
  ui.trito->setText(variant.toString());
}

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**spirit** · 23rd September 2008, 10:57

the wrong code in cpp file

Qt Code:

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...
parathiro::parathiro(QWidget *parent = 0, database *d)
...

...
parathiro::parathiro(QWidget *parent = 0, database *d)
...

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must be

Qt Code:

Switch view

...
parathiro::parathiro(QWidget *parent, database *d)
...

...
parathiro::parathiro(QWidget *parent, database *d)
...

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**spirit** · 23rd September 2008, 11:32

actually, I suggest you to use QSqlDatabase::database and refuse to use pointer to database object.

**cbarmpar** · 23rd September 2008, 14:42

i tried almost everything and it doesnt seem to work. Additionaly the eclipse IDE seems to stuck sometimes and i need to clean the project. most of the times even when i made the correct change the moc files get stuck andt.I see now why people dont prefer linux

I have attached the implementation together with the errors i recieve:

Qt Code:

Switch view

#include "kentriko.h"
#include <iostream>
#include <QString>
#include "../diafores_sinartisis/sinartisis.h"
#include <QMdiArea>
#include <QMdiSubWindow>
#include "../kentriko/parathiro/parathiro.h"
using namespace std;
 
kentriko::kentriko(QWidget *parent)
    : QMainWindow(parent)
{
	ui.setupUi(this);
	connect(ui.neo_parathiro, SIGNAL(triggered()), this, SLOT(anixe()));
	connect(ui.sindesi,SIGNAL(triggered()),this,SLOT(sindesi()));
}
void kentriko::anixe(){
    parathiro *para = new parathiro(0,d);
	QMdiSubWindow *subwindow = ui.mdiArea->addSubWindow(para);
	subwindow->setAttribute(Qt::WA_DeleteOnClose);
	subwindow->resize(sizeHint());
	subwindow->show();
}
 
void kentriko::sindesi(){
	database *d = new database;
	d->show();
}

#include "kentriko.h"
#include <iostream>
#include <QString>
#include "../diafores_sinartisis/sinartisis.h"
#include <QMdiArea>
#include <QMdiSubWindow>
#include "../kentriko/parathiro/parathiro.h"
using namespace std;

kentriko::kentriko(QWidget *parent)
    : QMainWindow(parent)
{
	ui.setupUi(this);
	connect(ui.neo_parathiro, SIGNAL(triggered()), this, SLOT(anixe()));
	connect(ui.sindesi,SIGNAL(triggered()),this,SLOT(sindesi()));
}
void kentriko::anixe(){
    parathiro *para = new parathiro(0,d);
	QMdiSubWindow *subwindow = ui.mdiArea->addSubWindow(para);
	subwindow->setAttribute(Qt::WA_DeleteOnClose);
	subwindow->resize(sizeHint());
	subwindow->show();
}

void kentriko::sindesi(){
	database *d = new database;
	d->show();
}

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the parathiro implementation:

Qt Code:

Switch view

#include "parathiro.h"
#include <iostream>
#include <QString>
#include "../diafores_sinartisis/sinartisis.h"
#include "../database/database.h"
 #include <QMainWindow>
using namespace std;
 
parathiro::parathiro(QWidget *parent, database *d)//<--- unsued parameter 'd'
    : QMainWindow(parent)
{
	ui.setupUi(this);
	connect(ui.anixe, SIGNAL(clicked()) , this , SLOT(anixe()));
	connect(ui.pare, SIGNAL(clicked()) , this , SLOT(pare()));
	connect(ui.proto,SIGNAL(textChanged(const QString&)),this,SLOT(alagi()));
}
 
void parathiro::alagi(){
  QSqlQuery erotisi( *d->get_db());
  proto = sinartisi_SELECT( "onoma,epitheto" ,"onomata", "onoma", ui.proto->text());
  ui.deytero->setText(proto);
  erotisi.exec(proto);
  variant = erotisi.size();
  ui.trito->setText(variant.toString());
}

#include "parathiro.h"
#include <iostream>
#include <QString>
#include "../diafores_sinartisis/sinartisis.h"
#include "../database/database.h"
 #include <QMainWindow>
using namespace std;

parathiro::parathiro(QWidget *parent, database *d)//<--- unsued parameter 'd'
    : QMainWindow(parent)
{
	ui.setupUi(this);
	connect(ui.anixe, SIGNAL(clicked()) , this , SLOT(anixe()));
	connect(ui.pare, SIGNAL(clicked()) , this , SLOT(pare()));
	connect(ui.proto,SIGNAL(textChanged(const QString&)),this,SLOT(alagi()));
}

void parathiro::alagi(){
  QSqlQuery erotisi( *d->get_db());
  proto = sinartisi_SELECT( "onoma,epitheto" ,"onomata", "onoma", ui.proto->text());
  ui.deytero->setText(proto);
  erotisi.exec(proto);
  variant = erotisi.size();
  ui.trito->setText(variant.toString());
}

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and finally the database implementation:

Qt Code:

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#include "database.h"
 
database::database(QWidget *parent) :
	QDialog(parent) {
	ui.setupUi(this);
	db = QSqlDatabase::addDatabase("QMYSQL");
	connect(ui.sindesi, SIGNAL(clicked()), this, SLOT(sindesou()));
	connect(ui.aposindesi, SIGNAL(clicked()), this, SLOT(aposindesou()));
	connect(ui.pliroforia_k, SIGNAL(clicked()), this, SLOT(pliroforia()));
}
void database::sindesou() {
	ena.pinakas = ui.pinakas->text();
	ena.onoma = ui.onoma->text();
	ena.kodikos = ui.kodikos->text();
	if (!db.isOpen()) {
		db.setDatabaseName(ena.pinakas);
		db.setUserName(ena.onoma);
		db.setPassword(ena.kodikos);
		db.setHostName("127.0.0.1");
		db.setPort( 3306);
		if (!db.open()) {
			ui.katastasi->setText("Not connected");
		} else {
			ui.katastasi->setText("connected");
		}
	} else {
		ui.katastasi->setText("It has already been connected");
	}
}
 
..............
QSqlDatabase * database::get_db() {
	return &db;
}

#include "database.h"

database::database(QWidget *parent) :
	QDialog(parent) {
	ui.setupUi(this);
	db = QSqlDatabase::addDatabase("QMYSQL");
	connect(ui.sindesi, SIGNAL(clicked()), this, SLOT(sindesou()));
	connect(ui.aposindesi, SIGNAL(clicked()), this, SLOT(aposindesou()));
	connect(ui.pliroforia_k, SIGNAL(clicked()), this, SLOT(pliroforia()));
}
void database::sindesou() {
	ena.pinakas = ui.pinakas->text();
	ena.onoma = ui.onoma->text();
	ena.kodikos = ui.kodikos->text();
	if (!db.isOpen()) {
		db.setDatabaseName(ena.pinakas);
		db.setUserName(ena.onoma);
		db.setPassword(ena.kodikos);
		db.setHostName("127.0.0.1");
		db.setPort( 3306);
		if (!db.open()) {
			ui.katastasi->setText("Not connected");
		} else {
			ui.katastasi->setText("connected");
		}
	} else {
		ui.katastasi->setText("It has already been connected");
	}
}

..............
QSqlDatabase * database::get_db() {
	return &db;
}

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Many thanks for your support so far.

Regards.

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