Share data while the Internet is available using flutter-CodePudding

I have a query I would like to store some data in the cache in the event that the phone is not connected to the Internet and when I connect to the Internet, it is sent to the server. I would like to know the best scenario for this case...

And thank u.

CodePudding user response：

You can try saving the data to the server and on failure you can write it in cache. Like

var response = await http.post(Uri.parse("api url here"),
          body: json.encode(body),
);
if(response.statusCode != 200)
{
  //save data in local like for example
  SharedPreferences prefs = await SharedPreferences.getInstance();
  prefs.setString("apiBody", json.encode(body);
}

CodePudding user response：

If you need to store or receive a large amount of data, consider to store this datas in a localdatabase like sqflite: https://pub.dev/packages/sqflite

base on SQLLite, you can store and manipulate data with SQL queries.

Here is an example DB helper call that manipulate customer datas:

class DBProvider {
  DBProvider._();

  static final DBProvider db = DBProvider._();

  late Database _database;

  Future<Database> get database async {
    _database = await initDB();
    return _database;
  }

  initDB() async {
    Directory documentsDirectory = await getApplicationDocumentsDirectory();
    String path = join(
      documentsDirectory.path,
      "andidoor.db",
    );

    return await openDatabase(
      path,
      version: 2,
      onOpen: (db) {},
      onCreate: createDatabase,
      onUpgrade: upgradeDatabase,
    );
  }

  upgradeDatabase(Database db, int oldVersion, int newVersion) async {
    print('Upgrade Database ...');
  }

  createDatabase(Database db, int version) async {
    print('Create Database ...');
    await db.execute("CREATE TABLE customers ("
        "id INTEGER PRIMARY KEY,"
        "user_id INTEGER,"
        "company TEXT,"
        "address_1 TEXT,"
        "address_2 TEXT,"
        "address_3 TEXT,"
        "zipcode TEXT,"
        "city TEXT,"
        "country TEXT,"
        "email TEXT,"
        "phone TEXT,"
        "status INTEGER,"
        "synced TEXT"
        ")");
  /**
   * Customers helper functions
   */

  Future<List<dynamic>> getCustomers() async {
    Database db = await database;
    return await db.rawQuery('SELECT * FROM customers ');
  }

  Future<void> populateCustomers(List<dynamic> customers) async {
    final completer = Completer();

    await deleteAllcustomers();

    for (var i = 0; i < customers.length; i  ) {
      await addCustomer(Customer.fromMap(customers[i]), true);
    }

    completer.complete();

    return completer.future;
  }

  Future<dynamic> deleteAllcustomers() async {
    Database db = await database;
    return await db.rawQuery('DELETE FROM customers');
  }

  Future<dynamic> deleteCustomer(String customerID) async {
    final db = await database;
    return db.delete(
      "customers",
      where: "id = ? ",
      whereArgs: [customerID],
    );
  }
}

And in other dart file just use like this:

final db = DBProvider.db;
List<dynamic> allDatas = [];
allDatas = await db.getCustomers();