31.8. Data persistence with SQLite in Flutter: Using transactions

One of the most crucial aspects of application development is data persistence. In Flutter, one of the most popular libraries for data persistence is SQLite. In this module of our course, we will cover in detail how to use transactions in SQLite with Flutter.

SQLite is an embedded SQL database engine that does not require a separate server process and allows you to store the database on disk or in memory. It is an excellent option for storing data locally on mobile devices, due to its lightness and efficiency.

Introduction to SQLite

SQLite is a relational database, which means that it organizes data into tables and allows you to perform complex query operations. The SQLite library in Flutter is called 'sqflite'. To start using it, you need to add it to your project's pubspec.yaml file.

Transactions in SQLite

A transaction is a unit of work that is performed as a single operation. This means that either all changes made during the transaction are applied to the database, or none of them are. This is useful for ensuring data consistency.

In SQLite, transactions are started with the beginTransaction method and completed with the setTransactionSuccessful method followed by the endTransaction method. If something goes wrong during the transaction, you can call the endTransaction method without calling the setTransactionSuccessful method to revert all changes.

Using transactions with Flutter and SQLite

To use transactions in Flutter with SQLite, you first need to open a database connection. This can be done with the openDatabase method, which returns a Database object.

After opening the connection, you can start a transaction by calling the transaction method on the Database object. This method receives a callback function that is called with a Transaction object. You can then use this object to perform database operations.

Here is an example of how to use a transaction to insert data into a table:

await db.transaction((txn) async {
  int id = await txn.rawInsert(
    'INSERT INTO Test(name, value) VALUES("some name", 1234)'
  );
  print('inserted: $id');
});

In this example, if the insert fails for some reason, the transaction will automatically roll back and no data will be inserted into the database.

Conclusion

Data persistence is a crucial aspect of application development, and with SQLite in Flutter, you can ensure that your data is stored securely and efficiently. Transactions provide a way to ensure data consistency by allowing multiple operations to be performed as a single operation.

We hope this module has given you a solid understanding of how to use SQLite transactions in Flutter. In the next module, we'll continue to explore more SQLite features and how they can be used in Flutter.