Qt 5.9 | Qt SQL | SQL Widget Mapper Example | window.cpp Example File

Qt 5.9.9 Reference Documentation

# window.cpp Example File

sqlwidgetmapper/window.cpp

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      #include <QtWidgets>
      #include <QtSql>

      #include "window.h"

      Window::Window(QWidget *parent)
          : QWidget(parent)
      {
          setupModel();

          nameLabel = new QLabel(tr("Na&me:"));
          nameEdit = new QLineEdit();
          addressLabel = new QLabel(tr("&Address:"));
          addressEdit = new QTextEdit();
          typeLabel = new QLabel(tr("&Type:"));
          typeComboBox = new QComboBox();
          nextButton = new QPushButton(tr("&Next"));
          previousButton = new QPushButton(tr("&Previous"));

          nameLabel->setBuddy(nameEdit);
          addressLabel->setBuddy(addressEdit);
          typeLabel->setBuddy(typeComboBox);

          QSqlTableModel *relModel = model->relationModel(typeIndex);
          typeComboBox->setModel(relModel);
          typeComboBox->setModelColumn(relModel->fieldIndex("description"));

          mapper = new QDataWidgetMapper(this);
          mapper->setModel(model);
          mapper->setItemDelegate(new QSqlRelationalDelegate(this));
          mapper->addMapping(nameEdit, model->fieldIndex("name"));
          mapper->addMapping(addressEdit, model->fieldIndex("address"));
          mapper->addMapping(typeComboBox, typeIndex);

          connect(previousButton, &QPushButton::clicked,
                  mapper, &QDataWidgetMapper::toPrevious);
          connect(nextButton, &QPushButton::clicked,
                  mapper, &QDataWidgetMapper::toNext);
          connect(mapper, &QDataWidgetMapper::currentIndexChanged,
                  this, &Window::updateButtons);

          QGridLayout *layout = new QGridLayout();
          layout->addWidget(nameLabel, 0, 0, 1, 1);
          layout->addWidget(nameEdit, 0, 1, 1, 1);
          layout->addWidget(previousButton, 0, 2, 1, 1);
          layout->addWidget(addressLabel, 1, 0, 1, 1);
          layout->addWidget(addressEdit, 1, 1, 2, 1);
          layout->addWidget(nextButton, 1, 2, 1, 1);
          layout->addWidget(typeLabel, 3, 0, 1, 1);
          layout->addWidget(typeComboBox, 3, 1, 1, 1);
          setLayout(layout);

          setWindowTitle(tr("SQL Widget Mapper"));
          mapper->toFirst();
      }

      void Window::setupModel()
      {
          QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
          db.setDatabaseName(":memory:");
          if (!db.open()) {
              QMessageBox::critical(0, tr("Cannot open database"),
                  tr("Unable to establish a database connection.\n"
                     "This example needs SQLite support. Please read "
                     "the Qt SQL driver documentation for information how "
                     "to build it."), QMessageBox::Cancel);
              return;
          }

          QSqlQuery query;
          query.exec("create table person (id int primary key, "
                     "name varchar(20), address varchar(200), typeid int)");
          query.exec("insert into person values(1, 'Alice', "
                     "'<qt>123 Main Street<br/>Market Town</qt>', 101)");
          query.exec("insert into person values(2, 'Bob', "
                     "'<qt>PO Box 32<br/>Mail Handling Service"
                     "<br/>Service City</qt>', 102)");
          query.exec("insert into person values(3, 'Carol', "
                     "'<qt>The Lighthouse<br/>Remote Island</qt>', 103)");
          query.exec("insert into person values(4, 'Donald', "
                     "'<qt>47338 Park Avenue<br/>Big City</qt>', 101)");
          query.exec("insert into person values(5, 'Emma', "
                     "'<qt>Research Station<br/>Base Camp<br/>"
                     "Big Mountain</qt>', 103)");

          query.exec("create table addresstype (id int, description varchar(20))");
          query.exec("insert into addresstype values(101, 'Home')");
          query.exec("insert into addresstype values(102, 'Work')");
          query.exec("insert into addresstype values(103, 'Other')");

          model = new QSqlRelationalTableModel(this);
          model->setTable("person");
          model->setEditStrategy(QSqlTableModel::OnManualSubmit);

          typeIndex = model->fieldIndex("typeid");

          model->setRelation(typeIndex,
                 QSqlRelation("addresstype", "id", "description"));
          model->select();
      }

      void Window::updateButtons(int row)
      {
          previousButton->setEnabled(row > 0);
          nextButton->setEnabled(row < model->rowCount() - 1);
      }