Qt 4.6: window.cpp Example File (sql/sqlwidgetmapper/window.cpp)

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# window.cpp Example File
sql/sqlwidgetmapper/window.cpp

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     #include <QtGui>
     #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, SIGNAL(clicked()),
                 mapper, SLOT(toPrevious()));
         connect(nextButton, SIGNAL(clicked()),
                 mapper, SLOT(toNext()));
         connect(mapper, SIGNAL(currentIndexChanged(int)),
                 this, SLOT(updateButtons(int)));

         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);
     }