Qt 4.8: browser.cpp Example File (demos/sqlbrowser/browser.cpp)

Qt Reference Documentation

- Qt 4.8
- ALL VERSIONS

- A
- A
- A
- Print

# browser.cpp Example File

demos/sqlbrowser/browser.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2015 The Qt Company Ltd.
     ** Contact: http://www.qt.io/licensing/
     **
     ** This file is part of the demonstration applications of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:LGPL$
     ** Commercial License Usage
     ** Licensees holding valid commercial Qt licenses may use this file in
     ** accordance with the commercial license agreement provided with the
     ** Software or, alternatively, in accordance with the terms contained in
     ** a written agreement between you and The Qt Company. For licensing terms
     ** and conditions see http://www.qt.io/terms-conditions. For further
     ** information use the contact form at http://www.qt.io/contact-us.
     **
     ** GNU Lesser General Public License Usage
     ** Alternatively, this file may be used under the terms of the GNU Lesser
     ** General Public License version 2.1 or version 3 as published by the Free
     ** Software Foundation and appearing in the file LICENSE.LGPLv21 and
     ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
     ** following information to ensure the GNU Lesser General Public License
     ** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
     ** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
     **
     ** As a special exception, The Qt Company gives you certain additional
     ** rights. These rights are described in The Qt Company LGPL Exception
     ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
     **
     ** GNU General Public License Usage
     ** Alternatively, this file may be used under the terms of the GNU
     ** General Public License version 3.0 as published by the Free Software
     ** Foundation and appearing in the file LICENSE.GPL included in the
     ** packaging of this file.  Please review the following information to
     ** ensure the GNU General Public License version 3.0 requirements will be
     ** met: http://www.gnu.org/copyleft/gpl.html.
     **
     ** $QT_END_LICENSE$
     **
     ****************************************************************************/

     #include "browser.h"
     #include "qsqlconnectiondialog.h"

     #include <QtGui>
     #include <QtSql>

     Browser::Browser(QWidget *parent)
         : QWidget(parent)
     {
         setupUi(this);

         table->addAction(insertRowAction);
         table->addAction(deleteRowAction);

         if (QSqlDatabase::drivers().isEmpty())
             QMessageBox::information(this, tr("No database drivers found"),
                                      tr("This demo requires at least one Qt database driver. "
                                         "Please check the documentation how to build the "
                                         "Qt SQL plugins."));

         emit statusMessage(tr("Ready."));
     }

     Browser::~Browser()
     {
     }

     void Browser::exec()
     {
         QSqlQueryModel *model = new QSqlQueryModel(table);
         model->setQuery(QSqlQuery(sqlEdit->toPlainText(), connectionWidget->currentDatabase()));
         table->setModel(model);

         if (model->lastError().type() != QSqlError::NoError)
             emit statusMessage(model->lastError().text());
         else if (model->query().isSelect())
             emit statusMessage(tr("Query OK."));
         else
             emit statusMessage(tr("Query OK, number of affected rows: %1").arg(
                                model->query().numRowsAffected()));

         updateActions();
     }

     QSqlError Browser::addConnection(const QString &driver, const QString &dbName, const QString &host,
                                 const QString &user, const QString &passwd, int port)
     {
         static int cCount = 0;

         QSqlError err;
         QSqlDatabase db = QSqlDatabase::addDatabase(driver, QString("Browser%1").arg(++cCount));
         db.setDatabaseName(dbName);
         db.setHostName(host);
         db.setPort(port);
         if (!db.open(user, passwd)) {
             err = db.lastError();
             db = QSqlDatabase();
             QSqlDatabase::removeDatabase(QString("Browser%1").arg(cCount));
         }
         connectionWidget->refresh();

         return err;
     }

     void Browser::addConnection()
     {
         QSqlConnectionDialog dialog(this);
         if (dialog.exec() != QDialog::Accepted)
             return;

         if (dialog.useInMemoryDatabase()) {
             QSqlDatabase::database("in_mem_db", false).close();
             QSqlDatabase::removeDatabase("in_mem_db");
             QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", "in_mem_db");
             db.setDatabaseName(":memory:");
             if (!db.open())
                 QMessageBox::warning(this, tr("Unable to open database"), tr("An error occurred while "
                                                                              "opening the connection: ") + db.lastError().text());
             QSqlQuery q("", db);
             q.exec("drop table Movies");
             q.exec("drop table Names");
             q.exec("create table Movies (id integer primary key, Title varchar, Director varchar, Rating number)");
             q.exec("insert into Movies values (0, 'Metropolis', 'Fritz Lang', '8.4')");
             q.exec("insert into Movies values (1, 'Nosferatu, eine Symphonie des Grauens', 'F.W. Murnau', '8.1')");
             q.exec("insert into Movies values (2, 'Bis ans Ende der Welt', 'Wim Wenders', '6.5')");
             q.exec("insert into Movies values (3, 'Hardware', 'Richard Stanley', '5.2')");
             q.exec("insert into Movies values (4, 'Mitchell', 'Andrew V. McLaglen', '2.1')");
             q.exec("create table Names (id integer primary key, Firstname varchar, Lastname varchar, City varchar)");
             q.exec("insert into Names values (0, 'Sala', 'Palmer', 'Morristown')");
             q.exec("insert into Names values (1, 'Christopher', 'Walker', 'Morristown')");
             q.exec("insert into Names values (2, 'Donald', 'Duck', 'Andeby')");
             q.exec("insert into Names values (3, 'Buck', 'Rogers', 'Paris')");
             q.exec("insert into Names values (4, 'Sherlock', 'Holmes', 'London')");
             connectionWidget->refresh();
         } else {
             QSqlError err = addConnection(dialog.driverName(), dialog.databaseName(), dialog.hostName(),
                                dialog.userName(), dialog.password(), dialog.port());
             if (err.type() != QSqlError::NoError)
                 QMessageBox::warning(this, tr("Unable to open database"), tr("An error occurred while "
                                            "opening the connection: ") + err.text());
         }
     }

     void Browser::showTable(const QString &t)
     {
         QSqlTableModel *model = new QSqlTableModel(table, connectionWidget->currentDatabase());
         model->setEditStrategy(QSqlTableModel::OnRowChange);
         model->setTable(connectionWidget->currentDatabase().driver()->escapeIdentifier(t, QSqlDriver::TableName));
         model->select();
         if (model->lastError().type() != QSqlError::NoError)
             emit statusMessage(model->lastError().text());
         table->setModel(model);
         table->setEditTriggers(QAbstractItemView::DoubleClicked|QAbstractItemView::EditKeyPressed);

         connect(table->selectionModel(), SIGNAL(currentRowChanged(QModelIndex,QModelIndex)),
                 this, SLOT(currentChanged()));
         updateActions();
     }

     void Browser::showMetaData(const QString &t)
     {
         QSqlRecord rec = connectionWidget->currentDatabase().record(t);
         QStandardItemModel *model = new QStandardItemModel(table);

         model->insertRows(0, rec.count());
         model->insertColumns(0, 7);

         model->setHeaderData(0, Qt::Horizontal, "Fieldname");
         model->setHeaderData(1, Qt::Horizontal, "Type");
         model->setHeaderData(2, Qt::Horizontal, "Length");
         model->setHeaderData(3, Qt::Horizontal, "Precision");
         model->setHeaderData(4, Qt::Horizontal, "Required");
         model->setHeaderData(5, Qt::Horizontal, "AutoValue");
         model->setHeaderData(6, Qt::Horizontal, "DefaultValue");

         for (int i = 0; i < rec.count(); ++i) {
             QSqlField fld = rec.field(i);
             model->setData(model->index(i, 0), fld.name());
             model->setData(model->index(i, 1), fld.typeID() == -1
                     ? QString(QVariant::typeToName(fld.type()))
                     : QString("%1 (%2)").arg(QVariant::typeToName(fld.type())).arg(fld.typeID()));
             model->setData(model->index(i, 2), fld.length());
             model->setData(model->index(i, 3), fld.precision());
             model->setData(model->index(i, 4), fld.requiredStatus() == -1 ? QVariant("?")
                     : QVariant(bool(fld.requiredStatus())));
             model->setData(model->index(i, 5), fld.isAutoValue());
             model->setData(model->index(i, 6), fld.defaultValue());
         }

         table->setModel(model);
         table->setEditTriggers(QAbstractItemView::NoEditTriggers);

         updateActions();
     }

     void Browser::insertRow()
     {
         QSqlTableModel *model = qobject_cast<QSqlTableModel *>(table->model());
         if (!model)
             return;

         QModelIndex insertIndex = table->currentIndex();
         int row = insertIndex.row() == -1 ? 0 : insertIndex.row();
         model->insertRow(row);
         insertIndex = model->index(row, 0);
         table->setCurrentIndex(insertIndex);
         table->edit(insertIndex);
     }

     void Browser::deleteRow()
     {
         QSqlTableModel *model = qobject_cast<QSqlTableModel *>(table->model());
         if (!model)
             return;

         model->setEditStrategy(QSqlTableModel::OnManualSubmit);

         QModelIndexList currentSelection = table->selectionModel()->selectedIndexes();
         for (int i = 0; i < currentSelection.count(); ++i) {
             if (currentSelection.at(i).column() != 0)
                 continue;
             model->removeRow(currentSelection.at(i).row());
         }

         model->submitAll();
         model->setEditStrategy(QSqlTableModel::OnRowChange);

         updateActions();
     }

     void Browser::updateActions()
     {
         bool enableIns = qobject_cast<QSqlTableModel *>(table->model());
         bool enableDel = enableIns && table->currentIndex().isValid();

         insertRowAction->setEnabled(enableIns);
         deleteRowAction->setEnabled(enableDel);
     }

     void Browser::about()
     {
         QMessageBox::about(this, tr("About"), tr("The SQL Browser demonstration "
             "shows how a data browser can be used to visualize the results of SQL"
             "statements on a live database"));
     }