Problem with adding rows into QTableView

[januszmk]

Hello!
I have problem with QTableView and QStandardItemModel
My header file:

#ifndef TABLEVIEW_H
#define TABLEVIEW_H
 
#include <QtGui>
#include <QWidget>
#include <QTableView>
#include <QStandardItemModel>
#include <QStandardItem>
#include <QString>
#include <QVector>
#include <QtSql/QSqlDatabase>
#include <QtSql/QSqlError>
#include <QtSql/QSqlQuery>
#include <QtSql/QSQLiteDriver>
#include <QMessageBox>
#include <QDialog>
#include "dialog.h"
 
class tableView : public QWidget
{
    Q_OBJECT
public:
    tableView(QWidget *parent = 0);
    void db_add(QString atr1, QString atr2);
    QStandardItemModel *model;
 
private:
    QString sstr;
    QTableView *tblv;
    QLabel *label1, *label2;
    QLineEdit *lineeRow, *lineeCol;
    QPushButton *btnApply;
    int nrow, ncol;
    QVector<QString> table;
    int db_connect();
    void btnApply_clicked();
    QString asda;
    QSqlDatabase db;
    int a;
    QStandardItem *item;
private slots:
    void dial();
};
 
#endif // TABLEVIEW_H

#ifndef TABLEVIEW_H
#define TABLEVIEW_H

#include <QtGui>
#include <QWidget>
#include <QTableView>
#include <QStandardItemModel>
#include <QStandardItem>
#include <QString>
#include <QVector>
#include <QtSql/QSqlDatabase>
#include <QtSql/QSqlError>
#include <QtSql/QSqlQuery>
#include <QtSql/QSQLiteDriver>
#include <QMessageBox>
#include <QDialog>
#include "dialog.h"

class tableView : public QWidget
{
    Q_OBJECT
public:
    tableView(QWidget *parent = 0);
    void db_add(QString atr1, QString atr2);
    QStandardItemModel *model;

private:
    QString sstr;
    QTableView *tblv;
    QLabel *label1, *label2;
    QLineEdit *lineeRow, *lineeCol;
    QPushButton *btnApply;
    int nrow, ncol;
    QVector<QString> table;
    int db_connect();
    void btnApply_clicked();
    QString asda;
    QSqlDatabase db;
    int a;
    QStandardItem *item;
private slots:
    void dial();
};

#endif // TABLEVIEW_H

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source file:

#include "tableview.h"
#include <QDebug>
 
tableView::tableView(QWidget *parent)
    : QWidget(parent)
{
 
    //create layout
    QVBoxLayout *mainLayout = new QVBoxLayout();
    QHBoxLayout *horLayout1 = new QHBoxLayout;
    QHBoxLayout *horLayout2 = new QHBoxLayout;
 
    btnApply = new QPushButton(tr("Apply"));
 
 
    //create QTableView
    tblv = new QTableView();
    tblv->setSelectionBehavior(QAbstractItemView::SelectItems );
    tblv->setSelectionMode( QAbstractItemView::ExtendedSelection );
    //setting layout
    mainLayout->addLayout(horLayout1);
    mainLayout->addLayout(horLayout2);
    mainLayout->addWidget(btnApply);
    mainLayout->addWidget(tblv);
    setLayout(mainLayout);
    connect(btnApply, SIGNAL(clicked()), this, SLOT(dial()));
    btnApply_clicked();
 
}
void tableView::dial()
{
    Dialog dial;
    dial.show();
    dial.exec();
}
 
int tableView::db_connect()
{
    if(!db.isOpen())
    {
        db = QSqlDatabase::addDatabase("QSQLITE");
        db.setDatabaseName("./baza.db");
        if (!db.open())
        {
            QMessageBox::critical(0, qApp->tr("Nie udało się nawiązać połączenia z bazą danych!"),
                                              qApp->tr("Naciśnij Cancel aby zakończyć."), QMessageBox::Cancel);
        }
        return 1;
    }
    return 0;
}
 
void tableView::db_add(QString atr1, QString atr2)
{
    QSqlQuery query;
    QString asda;
    asda = QString("insert into person values(null, '");
    asda += atr1;
    asda += "', '";
    asda += atr2;
    asda += "')";
    qDebug() << asda;
    query.exec(asda);
    if(query.lastError().isValid())
        qDebug() << query.lastError();
    qDebug() << "1";
    item = new QStandardItem(query.lastInsertId().toString());
    qDebug() << "2";
    model->setItem(a, 0, item);
    qDebug() << "3";
    item = new QStandardItem(atr1);
    qDebug() << "4";
    model->setItem(a, 1, item);
    qDebug() << "5";
    item = new QStandardItem(atr2);
    qDebug() << "6";
    model->setItem(a, 2, item);
}
 
void tableView::btnApply_clicked()
{
    if(db_connect()==1)
    {
        //get number of input row and column
        nrow = 2;
        ncol = 3;
 
        //create model
        model = new QStandardItemModel( nrow, ncol, this );
 
       //create QTableview Horizontal Header
       // model->setHorizontalHeaderItem( r, new QStandardItem( QString("Column_ %0" ).arg(r+1)) );
    model->setHorizontalHeaderItem(0, new QStandardItem(QString("Lp.")));
    model->setHorizontalHeaderItem(1, new QStandardItem(QString("Nazwa")));
    model->setHorizontalHeaderItem(2, new QStandardItem(QString("Haslo")));
    QSqlQuery query;
 
    a = 0;
    query.exec("SELECT * from person");
    while(query.next())
    {
        for(int x=0; x<3; x++)
        {
            sstr = query.value(x).toString();
 
            item = new QStandardItem(sstr);
            model->setItem(a, x, item);
        }
        a++;
    }
    //set model
    tblv->setModel(model);
 
    tblv->resizeRowsToContents();
    tblv->setFixedSize(800,600);
    tblv->setColumnWidth(2,350);
    tblv->setColumnWidth(1,350);
    tblv->setColumnWidth(0,50);
    tblv->scrollToBottom();
    }
}

#include "tableview.h"
#include <QDebug>

tableView::tableView(QWidget *parent)
    : QWidget(parent)
{

    //create layout
    QVBoxLayout *mainLayout = new QVBoxLayout();
    QHBoxLayout *horLayout1 = new QHBoxLayout;
    QHBoxLayout *horLayout2 = new QHBoxLayout;

    btnApply = new QPushButton(tr("Apply"));


    //create QTableView
    tblv = new QTableView();
    tblv->setSelectionBehavior(QAbstractItemView::SelectItems );
    tblv->setSelectionMode( QAbstractItemView::ExtendedSelection );
    //setting layout
    mainLayout->addLayout(horLayout1);
    mainLayout->addLayout(horLayout2);
    mainLayout->addWidget(btnApply);
    mainLayout->addWidget(tblv);
    setLayout(mainLayout);
    connect(btnApply, SIGNAL(clicked()), this, SLOT(dial()));
    btnApply_clicked();

}
void tableView::dial()
{
    Dialog dial;
    dial.show();
    dial.exec();
}

int tableView::db_connect()
{
    if(!db.isOpen())
    {
        db = QSqlDatabase::addDatabase("QSQLITE");
        db.setDatabaseName("./baza.db");
        if (!db.open())
        {
            QMessageBox::critical(0, qApp->tr("Nie udało się nawiązać połączenia z bazą danych!"),
                                              qApp->tr("Naciśnij Cancel aby zakończyć."), QMessageBox::Cancel);
        }
        return 1;
    }
    return 0;
}

void tableView::db_add(QString atr1, QString atr2)
{
    QSqlQuery query;
    QString asda;
    asda = QString("insert into person values(null, '");
    asda += atr1;
    asda += "', '";
    asda += atr2;
    asda += "')";
    qDebug() << asda;
    query.exec(asda);
    if(query.lastError().isValid())
        qDebug() << query.lastError();
    qDebug() << "1";
    item = new QStandardItem(query.lastInsertId().toString());
    qDebug() << "2";
    model->setItem(a, 0, item);
    qDebug() << "3";
    item = new QStandardItem(atr1);
    qDebug() << "4";
    model->setItem(a, 1, item);
    qDebug() << "5";
    item = new QStandardItem(atr2);
    qDebug() << "6";
    model->setItem(a, 2, item);
}

void tableView::btnApply_clicked()
{
    if(db_connect()==1)
    {
        //get number of input row and column
        nrow = 2;
        ncol = 3;

        //create model
        model = new QStandardItemModel( nrow, ncol, this );

       //create QTableview Horizontal Header
       // model->setHorizontalHeaderItem( r, new QStandardItem( QString("Column_ %0" ).arg(r+1)) );
    model->setHorizontalHeaderItem(0, new QStandardItem(QString("Lp.")));
    model->setHorizontalHeaderItem(1, new QStandardItem(QString("Nazwa")));
    model->setHorizontalHeaderItem(2, new QStandardItem(QString("Haslo")));
    QSqlQuery query;

    a = 0;
    query.exec("SELECT * from person");
    while(query.next())
    {
        for(int x=0; x<3; x++)
        {
            sstr = query.value(x).toString();

            item = new QStandardItem(sstr);
            model->setItem(a, x, item);
        }
        a++;
    }
    //set model
    tblv->setModel(model);
 
    tblv->resizeRowsToContents();
    tblv->setFixedSize(800,600);
    tblv->setColumnWidth(2,350);
    tblv->setColumnWidth(1,350);
    tblv->setColumnWidth(0,50);
    tblv->scrollToBottom();
    }
}

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in btnApply_Clicked() I am generating a table on base sqlite data.
in Dialog window I am giving arguments and calling up db_add function, then the arguments get into sqlite database and then I want to add this arguments to next rows in the QTableView, but when I run the program I get error of memory, and information in qt creator "exited with code -1073741819" when it get to item = new QStandardItem(query.lastInsertId().toString()). I tried give other argument (item = new QStandardItem(QString("test")) but it didn't help.
I would be grateful for your help, and sory for my bad english.
Janusz

[Santosh Reddy]

You are missing this statment in the tableView ctor

model = new QStandardItemModel(this);

model = new QStandardItemModel(this);

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[januszmk]

but

model = new QStandardItemModel(this);

model = new QStandardItemModel(this);

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is initiated in function btnApply_clicked. If it is about changing (nrow, ncol, this) into (this) then i tried to do that and it didn't help. program is crashing when is in function db_add, and get to any of function in model.

[Santosh Reddy]

you might be calling db_add before btnApply_clicked

[januszmk]

btnApply_clicked is calling when program is starting, and db_add when i press the button, another window show then i press the button on that window:

void Dialog::on_pushButton_clicked()
{
    text1 = ui->lineEdit->text();
    text2 = ui->lineEdit_2->text();
    if(!text1.isEmpty() && !text2.isEmpty())
    {
        tableView *table;
        table->db_add(text1,text2);
    }
    this->close();
}

void Dialog::on_pushButton_clicked()
{
    text1 = ui->lineEdit->text();
    text2 = ui->lineEdit_2->text();
    if(!text1.isEmpty() && !text2.isEmpty())
    {
        tableView *table;
        table->db_add(text1,text2);
    }
    this->close();
}

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I just check, and if i am calling function db_add in btnApply_clicked() then its work ok, so maybe i got error in dialog class?

#ifndef DIALOG_H
#define DIALOG_H
 
#include <QDialog>
#include <QString>
 
namespace Ui {
    class Dialog;
}
 
class Dialog : public QDialog
{
    Q_OBJECT
 
public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();
 
private slots:
 
    void on_pushButton_2_clicked();
 
    void on_pushButton_clicked();
 
private:
    Ui::Dialog *ui;
    QString text1;
    QString text2;
};
 
#endif // DIALOG_H

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QString>

namespace Ui {
    class Dialog;
}

class Dialog : public QDialog
{
    Q_OBJECT

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

private slots:

    void on_pushButton_2_clicked();

    void on_pushButton_clicked();

private:
    Ui::Dialog *ui;
    QString text1;
    QString text2;
};

#endif // DIALOG_H

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#include "dialog.h"
#include "ui_dialog.h"
#include "tableview.h"
 
Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
}
 
Dialog::~Dialog()
{
    delete ui;
}
 
 
void Dialog::on_pushButton_2_clicked()
{
    this->close();
}
 
void Dialog::on_pushButton_clicked()
{
    text1 = ui->lineEdit->text();
    text2 = ui->lineEdit_2->text();
    if(!text1.isEmpty() && !text2.isEmpty())
    {
        tableView *table;
        table->db_add(text1,text2);
    }
    this->close();
}

#include "dialog.h"
#include "ui_dialog.h"
#include "tableview.h"

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

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


void Dialog::on_pushButton_2_clicked()
{
    this->close();
}

void Dialog::on_pushButton_clicked()
{
    text1 = ui->lineEdit->text();
    text2 = ui->lineEdit_2->text();
    if(!text1.isEmpty() && !text2.isEmpty())
    {
        tableView *table;
        table->db_add(text1,text2);
    }
    this->close();
}

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i get in "Build Issues" "table may be used uninitialized in this function

[januszmk]

I maybe found solution, but don't know how to do it. Could someone tell me, how can I connect to signal clicked() on button from ui from other class? because even if I declare ui as public, i can't get to that button from tableView class:

Dialog dialog = new Dialog();
dialog->show();
dialog->exec();
connect(dialog->ui->pushButton, SIGNAL(clicked()),this,on_pushButton_clicked()); // <- there i have error

Dialog dialog = new Dialog();
dialog->show();
dialog->exec();
connect(dialog->ui->pushButton, SIGNAL(clicked()),this,on_pushButton_clicked()); // <- there i have error

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[stampede]

Look like you forgot the SLOT keyword:

connect(dialog->ui->pushButton, SIGNAL(clicked()),this,SLOT(on_pushButton_clicked()));

connect(dialog->ui->pushButton, SIGNAL(clicked()),this,SLOT(on_pushButton_clicked()));

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[Santosh Reddy]

Dialog dialog = new Dialog();
dialog->show();
connect(dialog->ui->pushButton, SIGNAL(clicked()),this,SLOT(on_pushButton_clicked())); //you missed SLOT keyword, and also you should connect before calling exec()
dialog->exec();

Dialog dialog = new Dialog();
dialog->show();
connect(dialog->ui->pushButton, SIGNAL(clicked()),this,SLOT(on_pushButton_clicked())); //you missed SLOT keyword, and also you should connect before calling exec()
dialog->exec();

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[januszmk]

Thank you very much, now everything is working.