Qt 5.11 | Qt SQL | SQL Browser | browser.cpp Example File

Qt 5.11.3 Reference Documentation

# browser.cpp Example File

sqlbrowser/browser.cpp

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

      #include <QtWidgets>
      #include <QtSql>

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

          table->addAction(insertRowAction);
          table->addAction(deleteRowAction);
          table->addAction(fieldStrategyAction);
          table->addAction(rowStrategyAction);
          table->addAction(manualStrategyAction);
          table->addAction(submitAction);
          table->addAction(revertAction);
          table->addAction(selectAction);

          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 CustomModel(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(), &QItemSelectionModel::currentRowChanged,
                  this, &Browser::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(QMetaType::typeName(fld.type()))
                      : QString("%1 (%2)").arg(QMetaType::typeName(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;

          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());
          }

          updateActions();
      }

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

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

          fieldStrategyAction->setEnabled(tm);
          rowStrategyAction->setEnabled(tm);
          manualStrategyAction->setEnabled(tm);
          submitAction->setEnabled(tm);
          revertAction->setEnabled(tm);
          selectAction->setEnabled(tm);

          if (tm) {
              QSqlTableModel::EditStrategy es = tm->editStrategy();
              fieldStrategyAction->setChecked(es == QSqlTableModel::OnFieldChange);
              rowStrategyAction->setChecked(es == QSqlTableModel::OnRowChange);
              manualStrategyAction->setChecked(es == QSqlTableModel::OnManualSubmit);
          }
      }

      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"));
      }

      void Browser::on_fieldStrategyAction_triggered()
      {
          QSqlTableModel * tm = qobject_cast<QSqlTableModel *>(table->model());
          if (tm)
              tm->setEditStrategy(QSqlTableModel::OnFieldChange);
      }

      void Browser::on_rowStrategyAction_triggered()
      {
          QSqlTableModel * tm = qobject_cast<QSqlTableModel *>(table->model());
          if (tm)
              tm->setEditStrategy(QSqlTableModel::OnRowChange);
      }

      void Browser::on_manualStrategyAction_triggered()
      {
          QSqlTableModel * tm = qobject_cast<QSqlTableModel *>(table->model());
          if (tm)
              tm->setEditStrategy(QSqlTableModel::OnManualSubmit);
      }

      void Browser::on_submitAction_triggered()
      {
          QSqlTableModel * tm = qobject_cast<QSqlTableModel *>(table->model());
          if (tm)
              tm->submitAll();
      }

      void Browser::on_revertAction_triggered()
      {
          QSqlTableModel * tm = qobject_cast<QSqlTableModel *>(table->model());
          if (tm)
              tm->revertAll();
      }

      void Browser::on_selectAction_triggered()
      {
          QSqlTableModel * tm = qobject_cast<QSqlTableModel *>(table->model());
          if (tm)
              tm->select();
      }