QTableView

lincoln

good afternoon with everyone, I have the following QDialog with a QTableView and a QLabel; then what I did was connect to a database, where I have saved images, these images, the information of these images I show them in rows in the QTableView and every time I select one of them the corresponding image is shown in the QLabel, until there everything is great; My question is how do I do the same when I go through each row of the QTableView, I mean when I use the keys up and down, because when I do that nothing is shown in the QLabel, I tried several things but it did not work, I hope you can help me is for a university project, I would appreciate any help, thanks in advance.

I hope you have given me to understand.

Note:
I leave the source code here.

the code of the main form.

#ifndef PRINCIPALFRM_H
#define PRINCIPALFRM_H

#include <QDialog>
#include <QSqlDatabase>
#include <QFile>
#include <QSqlTableModel>
namespace Ui {
class PrincipalFrm;
}

class PrincipalFrm : public QDialog
{
    Q_OBJECT

public:
    explicit PrincipalFrm(QWidget *parent = nullptr);
    ~PrincipalFrm();

private slots:
    void on_toolButton_clicked();

    void on_pushButton_clicked();
    void on_tableView_clicked(const QModelIndex &index);
    void on_pushButton_2_clicked();

private:
    Ui::PrincipalFrm *ui;
    QSqlDatabase db;
    QFile file;
    QSqlTableModel *model;
};

#endif // PRINCIPALFRM_H

here the .cpp

#include "principalfrm.h"
#include "ui_principalfrm.h"
#include <QMessageBox>
#include <QSqlError>
#include <QFileInfo>
#include <QFileDialog>
#include <QSqlQuery>
#include <QKeyEvent>
PrincipalFrm::PrincipalFrm(QWidget *parent) :
    QDialog(parent),ui(new Ui::PrincipalFrm)
{
    ui->setupUi(this);
    db=QSqlDatabase::addDatabase("QPSQL");
    if(!db.isDriverAvailable("QPSQL")){
        QMessageBox::critical(this,qApp->applicationName(),
                              tr("Ocurrio un error al cargar el controlador.\n").append(
                                  db.lastError().text()));
        return;
    }
    db.setHostName("127.0.0.1");
    db.setPort(5432);
    db.setDatabaseName("dbimagenes");
    db.setUserName("postgres");
    db.setPassword("2311046");
    if(!db.open()){
        QMessageBox::critical(this,qApp->applicationName(),
                              tr("Ocurrio un error al abrir la base de datos.\n").append(
                                  db.lastError().text()));
        return;
    }
    model=new QSqlTableModel(this);

    model->setTable("imagenes");
    model->select();
    model->setHeaderData(1,Qt::Horizontal,"Nombre imagen");
    model->setHeaderData(2,Qt::Horizontal,"Descripcion imagen");
    model->setHeaderData(3,Qt::Horizontal,"Imagen");
    ui->tableView->setModel(model);
//    setWindowFlags(Qt::Dialog|Qt::MSWindowsFixedSizeDialogHint|
//                   Qt::WindowMinimizeButtonHint|Qt::WindowCloseButtonHint);
    setWindowFlags(Qt::MSWindowsFixedSizeDialogHint);

    ui->tableView->setSelectionBehavior(QAbstractItemView::SelectRows);
    ui->tableView->setSelectionMode(QAbstractItemView::SingleSelection);
    ui->tableView->hideColumn(0);

    if(model->rowCount()==0){
        ui->pushButton_2->setEnabled(false);
    }
    ui->pushButton->setDefault(true);
    ui->pushButton_2->setShortcut(QKeySequence(Qt::Key_Q));
    ui->toolButton->setShortcut(QKeySequence(Qt::Key_A));

    ui->tableView->setColumnWidth(2,120);
}

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

void PrincipalFrm::on_toolButton_clicked()
{
    QString fileName=QFileDialog::getOpenFileName(this,"Abrir un aimagen",
                                 QDir::rootPath(),"Imagenes (*.png *.jpg *.jpeg)");
    file.setFileName(fileName);
    if(fileName.isEmpty()){
        return;
    }
    ui->lineEdit->setText(fileName);
    file.setFileName(fileName);
    QPixmap pixmap(fileName);
    ui->lblFoto->setPixmap(pixmap.scaled(ui->lblFoto->size()));

}
void PrincipalFrm::on_pushButton_clicked()
{
    if(ui->lineEdit->text().isEmpty()||ui->lineEdit_2->text().isEmpty()){
        QMessageBox::critical(this,qApp->applicationName(),
                              tr("Complete todos los campos."));
        ui->lineEdit_2->setFocus();
        return;
    }
    QFileInfo info(file);
    if(!file.open(QIODevice::ReadOnly)){
        return;
    }
    QByteArray imagen=file.readAll();
    QSqlQuery qry;
    qry.prepare("INSERT INTO imagenes(nombre,descripcion,img) VALUES(?,?,?)");
    qry.addBindValue(info.fileName(),QSql::In);
    qry.addBindValue(ui->lineEdit_2->text(),QSql::In);
    qry.addBindValue(imagen,QSql::In);
    if(!qry.exec()){
        QMessageBox::critical(this,qApp->applicationName(),
                              tr("Error de ejecucion.\n").append(
                                  qry.lastError().text()));
        return;
    }
    QMessageBox::information(this,qApp->applicationName(),
                             "Datos gusrdados!");
    ui->lineEdit->clear();
    ui->lineEdit_2->clear();
    ui->lblFoto->clear();
    model->select();
    file.close();
    if(model->rowCount()!=0){
        ui->pushButton_2->setEnabled(true);
    }

}
/**
This is where I show the images in the QLabel, by clicking on a row of the QTableView,
I want to do the same but when I slide through each row of the QTableView with the arrow keys,
that is the question.
**/
void PrincipalFrm::on_tableView_clicked(const QModelIndex &index)
{
    QSqlQuery qry;
    qry.prepare(("SELECT img FROM imagenes WHERE id_imagen=?"));
    qry.addBindValue(model->index(index.row(),0).data().toString());
    if(!qry.exec()){
        QMessageBox::critical(this,qApp->applicationName(),
                              tr("Error de ejecucion.\n").append(
                                  qry.lastError().text()));
        return;
    }
    qry.next();
    QByteArray imagen=qry.value(0).toByteArray();
    QPixmap pixmap;
    pixmap.loadFromData(imagen);
    ui->lblFoto->setPixmap(pixmap.scaled(ui->lblFoto->size()));
}

void PrincipalFrm::on_pushButton_2_clicked()
{
    QString nombre= model->index(ui->tableView->currentIndex().row(),1).data().toString();
   int res= QMessageBox::question(this,qApp->applicationName(),
                          QString("Seguro que quiere eliminar.").append("<h3>"+nombre+"</h3>"),
                                  QMessageBox::Yes|QMessageBox::No);

   if(res==QMessageBox::Yes){
       model->removeRow(ui->tableView->currentIndex().row());
       model->select();
       ui->tableView->selectRow(0);
   }

    if(model->rowCount()==0){
        ui->lblFoto->clear();
        ui->pushButton_2->setEnabled(false);
    }
    
}

Christian Ehrlicher

You can listen on QAbstractItemView::currentChanged()

lincoln

Some concrete example that you could provide, I say if it is possible.

Christian Ehrlicher

Just connect the signal with a slot in PrincipalFrm and do what you're doing in on_tableView_clicked()

lincoln

Hi, you know I did what you said, but when I want to connect the currentChanged signal, it just does not appear, which is what I'm doing wrong.

QObject::connect(ui->tableView, &QTableView::    ,this,[&](){

      QMessageBox::information(this,qApp->applicationName(),"Mensaje");
    });

SGaist

Hi,

Do you mean there's no auto-completion ? If so, that shouldn't stop you, write the name of the signal. If you make any mistake in it, the compilation will fail.

lincoln

the problem is not the auto completed, the problem is that the currentChanged () signal does not appear, when putting the four points, only one eslot appears and a function with the same name of the signal.

SGaist

Well, that sounds like the auto-complete feature malfunctioning. But again, that's just a helper. Write the signal name and go on with your application.

lincoln

Well, what I can say is that I have not achieved anything yet, and the truth is that I'm tired of searching and not getting an answer, thanks anyway.

jsulm

@lincoln Did you try to write

QObject::connect(ui->tableView, &QTableView::currentChanged, this,[&](){

      QMessageBox::information(this,qApp->applicationName(),"Mensaje");
    });

?
There is nothing to search, you just need to write what was already suggested...

lincoln

@jsulm said in QTableView:

QMessageBox::information(this,qApp->applicationName(),"Mensaje");

I already did that and when I do I get this error.

semmantic issue
55:49: error 'currentChanged' is a protected member of 'QTableView'
qtableview.h: 176: 10: note: declared protedted here

note:

I attached an image with the screenshot of the error that I get, thanks.![alt text]( image url)

Christian Ehrlicher

@Christian-Ehrlicher said in QTableView:

QAbstractItemView::currentChanged()

Ah, you have to go through the selectionModel, sorry

connect(ui->tableView->selectionModel, &QItemSelectionModel::currentChanged, ...)

lincoln

deluxe brother, thank you already solved my problem, greetings.