Segmentation fault using sqlite

[vidalpuga]

I know this is a typical error message, but I cannot find a solution in the other post I found on it.
I have the following code:

void Ligas::SetId(const QString s,QSqlDatabase *datos)
{
    if(datos == NULL){
        qDebug() << "NULL database";
        return;
    }
    if(!datos->isOpen()){
        qDebug() << "Failed to open the database";
        return;
    }
    qDebug() << "step 1: " << s;
    setWindowTitle(s);
    qDebug() << "step 2";
    ui->listWidget_estad->clear();
    qDebug() << "step 3";
    ui->listWidget_nombres->clear();
    qDebug() << "step 4";
...
}

void Ligas::SetId(const QString s,QSqlDatabase *datos)
{
    if(datos == NULL){
        qDebug() << "NULL database";
        return;
    }
    if(!datos->isOpen()){
        qDebug() << "Failed to open the database";
        return;
    }
    qDebug() << "step 1: " << s;
    setWindowTitle(s);
    qDebug() << "step 2";
    ui->listWidget_estad->clear();
    qDebug() << "step 3";
    ui->listWidget_nombres->clear();
    qDebug() << "step 4";
...
}

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I get to "Step 1" before the message error:

The inferior stopped because it received a signal from the Operating System.

Signal name : SIGSEGV
Signal meaning : Segmentation fault

If I delete setWindowTitle(s); I get the very same error after Step 2. So I am really confused. Can anybody help me?

The program used to work fine before adding new rows into the database.

[anda_skoa]

Is the Ligas object you are calling this on a valid one?

Cheers,
_

[vidalpuga]

I think so, because the program worked well before (adding new rows in the database).

The Ligas object is a MainWindow. This is ligas.h:

#ifndef LIGAS_H
#define LIGAS_H
 
#include <QMainWindow>
#include <QtSql>
 
namespace Ui {
class Ligas;
}
 
class Ligas : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit Ligas(QWidget *parent = 0);
    ~Ligas();
 
public slots:
    void SetId(const QString,QSqlDatabase *);
 
private:
    Ui::Ligas *ui;
};
 
#endif // LIGAS_H

#ifndef LIGAS_H
#define LIGAS_H

#include <QMainWindow>
#include <QtSql>

namespace Ui {
class Ligas;
}

class Ligas : public QMainWindow
{
    Q_OBJECT

public:
    explicit Ligas(QWidget *parent = 0);
    ~Ligas();

public slots:
    void SetId(const QString,QSqlDatabase *);

private:
    Ui::Ligas *ui;
};

#endif // LIGAS_H

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And this is ligas.cpp:

#include "ligas.h"
#include "mainwindow.h"
#include "ui_ligas.h"
 
Ligas::Ligas(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::Ligas)
{
    ui->setupUi(this);
}
 
Ligas::~Ligas()
{
    delete ui;
}
 
void Ligas::SetId(const QString s,QSqlDatabase *datos)
{...}

#include "ligas.h"
#include "mainwindow.h"
#include "ui_ligas.h"

Ligas::Ligas(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::Ligas)
{
    ui->setupUi(this);
}

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

void Ligas::SetId(const QString s,QSqlDatabase *datos)
{...}

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[ChrisW67]

Your parameter datos can be both not NULL and not valid. Are you sure you are passing a valid pointer that is still valid when this code uses it?

BTW,it is a little unusual to pass a QSqlDatabase by pointer.

[vidalpuga]

Your parameter datos can be both not NULL and not valid. Are you sure you are passing a valid pointer that is still valid when this code uses it?

I suspect it may be possible that I am passing an invalid pointer. But in that case I do not know why, nor why it used to work fine before.
This is the calling procedure:

void MainWindow::on_listWidget_competiciones_doubleClicked(const QModelIndex &index)
{
    qDebug() << "doubleclick";
    if(!datos.isOpen()){
        qDebug() << "Failed to open the database";
        return;
    }
    ligas->SetId(index.data().toString(),&datos);
    ligas->show();
    ligas->raise();
}

void MainWindow::on_listWidget_competiciones_doubleClicked(const QModelIndex &index)
{
    qDebug() << "doubleclick";
    if(!datos.isOpen()){
        qDebug() << "Failed to open the database";
        return;
    }
    ligas->SetId(index.data().toString(),&datos);
    ligas->show();
    ligas->raise();
}

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BTW,it is a little unusual to pass a QSqlDatabase by pointer.

So, what is the most usual way to do that ? To define it as a global variable?

[vidalpuga]

Is the Ligas object you are calling this on a valid one?

Cheers,
_

OK. I found the mistake. I had deleted "ligas = new Ligas" unwillingly. So that was the problem. Ligas was NULL.

I still don't know what is the best way to pass a QSqlDatabase. Isn't a good ideo to do it by pointer?