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// SPDX-FileCopyrightText: 2022 Jonah Brüchert <jbb@kaidan.im
//
// SPDX-License-Identifier: BSD-2-Clause
/*
* This example demonstrates how to use transactions with FutureSQL
* For explanations of the general concepts, see the hello-world example,
* which is very similar (except it doesn't use transactions, of course),
* but it contains more comments.
*/
// Qt
#include <QCoreApplication>
#include <QTimer>
// QCoro
#include <QCoro/QCoroTask>
#include <QCoro/QCoroFuture>
// FutureSQL
#include <ThreadedDatabase>
// STL
#include <tuple>
// Why is this function not part of the library, I hear you ask.
// Currently, FutureSQL should not hard-depend on QCoro,
// even though with Qt5, QCoro is the only way to use it without
// hand-crafting helper functions to deal with QFutures.
template <typename Func>
QCoro::Task<> transaction(std::unique_ptr<ThreadedDatabase> &database, Func queryFunc) {
co_await database->execute(QStringLiteral("BEGIN TRANSACTION"));
co_await queryFunc();
co_await database->execute(QStringLiteral("COMMIT"));
}
struct HelloWorld {
using ColumnTypes = std::tuple<int, QString>;
// attributes
int id;
QString data;
};
QCoro::Task<> databaseExample() {
// This object contains the database configuration,
// in this case just the path to the SQLite file, and the database type (SQLite).
DatabaseConfiguration config;
config.setDatabaseName(QStringLiteral("database.sqlite"));
config.setType(DatabaseType::SQLite);
// Here we open the database file, and get a handle to the database.
auto database = ThreadedDatabase::establishConnection(config);
// Run the following steps in a transaction
co_await transaction(database, [&database]() -> QCoro::Task<> {
// Create the table
co_await database->execute(QStringLiteral("CREATE TABLE IF NOT EXISTS test (id INTEGER PRIMARY KEY AUTOINCREMENT, data TEXT)"));
// Insert some initial data
co_await database->execute(QStringLiteral("INSERT INTO test (data) VALUES (?)"), QStringLiteral("Hello World"));
});
// Retrieve some data from the database.
// The data is directly returned as our HelloWorld struct.
auto results = co_await database->getResults<HelloWorld>(QStringLiteral("SELECT * FROM test"));
// Print out the data in the result list
for (const auto &result : results) {
qDebug() << result.id << result.data;
}
// Quit the event loop as we are done
QCoreApplication::instance()->quit();
}
// Just a minimal main function for QCoro, to start the Qt event loop.
int main(int argc, char *argv[]) {
QCoreApplication app(argc, argv);
QTimer::singleShot(0, databaseExample);
return app.exec();
}
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