Using SQLite in main.dart from seperate file? - sqlite

Question

I've followed this easy example from the flutter documentation. However, this is wrote in a separate file (db_test.db). I'm aiming to convert data into a ListView at some point. So, how would I use CRUD operations like retrieving data in my main.dart? I could add this to my main.dart file but I'd like to keep it clean and separate.
Official Flutter tutorial
My db.dart file
void main () async {
final database = openDatabase(
join(await getDatabasesPath(), 'to_do.db'),
onCreate: (db, version) {
return db.execute("CREATE TABLE tasks(id INTEGER PRIMARY KEY, title TEXT, created TEXT, INTEGER is_complete)");
},
version: 1,
);
Future<void> insertTask (Task task) async {
final Database db = await database;
await db.insert(
'tasks',
task.toMap(),
conflictAlgorithm: ConflictAlgorithm.replace
);
}
Future<List<Task>> tasks () async {
final Database db = await database;
final List<Map<String, dynamic>> maps = await db.query('tasks');
return List.generate(maps.length, (i) {
return Task(
id: maps[i]['id'],
title: maps[i]['title'],
created: maps[i]['created'],
isComplete: maps[i]['is_complete']
);
});
}
Future<void> updateTask(Task task) async {
// Get a reference to the database.
final db = await database;
// Update the given Dog.
await db.update(
'tasks',
task.toMap(),
// Ensure that the Dog has a matching id.
where: "id = ?",
// Pass the Dog's id as a whereArg to prevent SQL injection.
whereArgs: [task.id],
);
}
Future<void> deleteTask(int id) async {
// Get a reference to the database.
final db = await database;
// Remove the Dog from the database.
await db.delete(
'tasks',
// Use a `where` clause to delete a specific dog.
where: "id = ?",
// Pass the Dog's id as a whereArg to prevent SQL injection.
whereArgs: [id],
);
}
}

Answer 1

You can create a new file containing Class with static members to help. Static members ensure that only one instance of database is created in your whole app.
class DatabaseHelper {
static Database _database;
///Returns db instance if already opened
///else call the initDatabase
static Future<Database> getDBConnector() async {
if (_database != null) {
return _database;
}
return await _initDatabase();
}
///Open DB Connection, returns a Database instance.
///
static Future<Database> _initDatabase() async {
_database = await openDatabase(
join(await getDatabasesPath(), "my_path.db"),
onCreate: (db, version) async {
//on create
},
version: 1,
);
return _database;
}
//put your CRUD in static function
static Future<void> insertTask (Task task) async {
final Database db = await getDBConnector();
await db.insert(
'tasks',
task.toMap(),
conflictAlgorithm: ConflictAlgorithm.replace
);
}
//the same with edit, delete
}
Then in your other file (like main.dart) you can just call it like this:
import "./databaseHelper.dart";
void caller() async{
//create task
//insert
await DatabaseHelper.insertTask(task);
}
Make sure the caller is asynchronous.