Write Data to a Synced Database

struct Item {
  realm::primary_key<realm::object_id> _id{realm::object_id::generate()};
  std::string ownerId;
  std::string itemName;
  int64_t complexity;
};
REALM_SCHEMA(Item, _id, ownerId, itemName, complexity)

// The documentation does not currently have this code example in C#.
// Please refer to the other languages or related pages for example code.

@RealmModel()
class _Car {
  @MapTo("_id")
  @PrimaryKey()
  late ObjectId id;
  // This is the queryable field
  late String ownerId;
  late String make;
  late String? model;
  late int? miles;
}

// The documentation does not currently have this code example in JavaScript.
// Please refer to the other languages or related pages for example code.

class Item : RealmObject {
    @PrimaryKey
    var _id: ObjectId = ObjectId()
    var ownerId: String = ""
    var itemName: String = ""
    var complexity: Int = 0
}

class Item: Object {
    @Persisted(primaryKey: true) var _id: ObjectId
    @Persisted var ownerId: String
    @Persisted var itemName: String
    @Persisted var complexity: Int
}

// The documentation does not currently have this code example in TypeScript.
// Please refer to the other languages or related pages for example code.

auto appConfig = realm::App::configuration();
appConfig.app_id = APP_ID;
auto app = realm::App(appConfig);
auto user = app.login(realm::App::credentials::anonymous()).get();
auto dbConfig = user.flexible_sync_configuration();
auto syncRealm = realm::db(dbConfig);
// Add subscription
auto subscriptionUpdateSuccess =
    syncRealm.subscriptions()
        .update([](realm::mutable_sync_subscription_set &subs) {
          // Get Items from Atlas that match this query.
          // Uses the queryable field `complexity`.
          // Sync Item objects with complexity less than or equal to 4.
          subs.add<realm::Item>(
              "simple items", [](auto &obj) { return obj.complexity <= 4; });
        })
        .get();

final app = App(AppConfiguration(APP_ID));
final user = await app.logIn(Credentials.anonymous());
final config = Configuration.flexibleSync(user, [Car.schema]);
final realm = Realm(config);
// Add subscriptions
realm.subscriptions.update((mutableSubscriptions) {
  // Get Cars from Atlas that match the Realm Query Language query.
  // Uses the queryable field `miles`.
  // Query matches cars with less than 100 miles or `null` miles.
  final newCarQuery = realm.query<Car>("miles < 100 OR miles == \$0", [null]);
  mutableSubscriptions.add(newCarQuery, name: "new-car-subscription");
});
await realm.subscriptions.waitForSynchronization();

// The documentation does not currently have this code example in JavaScript.
// Please refer to the other languages or related pages for example code.

val app = App.create(FLEXIBLE_APP_ID)
val user = app.login(credentials)
val flexSyncConfig = SyncConfiguration.Builder(user, setOf(Item::class))
    // Add subscription
    .initialSubscriptions { realm ->
        add(
            // Get Items from Atlas that match the Realm Query Language query.
            // Uses the queryable field `complexity`.
            // Query matches objects with complexity less than or equal to 4.
            realm.query<Item>("complexity <= 4"),
            "simple-items"
        )
    }
    .build()
val syncRealm = Realm.open(flexSyncConfig)
syncRealm.subscriptions.waitForSynchronization()
Log.v("Successfully opened realm: ${syncRealm.configuration}")

let app = App(id: YOUR_APP_ID_HERE)
do {
    let user = try await app.login(credentials: Credentials.anonymous)
    do {
        var flexSyncConfig = user.flexibleSyncConfiguration()
        flexSyncConfig.objectTypes = [Item.self]
        let realm = try await Realm(configuration: flexSyncConfig)
        let subscriptions = realm.subscriptions
        try await subscriptions.update {
            subscriptions.append(
                QuerySubscription<Item>(name: "simple-items") {
                 $0.complexity <= 4
            })
        }
        print("Successfully opened realm: \(realm)")
    } catch {
        print("Failed to open realm: \(error.localizedDescription)")
        // handle error
    }
} catch {
    fatalError("Login failed: \(error.localizedDescription)")
}

// The documentation does not currently have this code example in TypeScript.
// Please refer to the other languages or related pages for example code.

// Per the Device Sync permissions, users can only read and write data
// where the `Item.ownerId` property matches their own user ID.
auto simpleItem =
    realm::Item{.ownerId = user.identifier(),
                          .itemName = "This item meets sync criteria",
                          .complexity = 3};
// `simpleItem` successfully writes to the realm and syncs to Atlas
// because its data matches the subscription query (complexity <= 4)
// and its `ownerId` field matches the user ID.
syncRealm.write([&] { syncRealm.add(std::move(simpleItem)); });

// The documentation does not currently have this code example in C#.
// Please refer to the other languages or related pages for example code.

// Per the Device Sync permissions, users can only read and write data
// where the `Car.ownerId` property matches their own user ID.
final userId = user.id;
realm.write(() {
  // WRITE SUCCEEDS
  // `newCar` is successfully written to the realm and synced to Atlas
  // because it's data matches the subscription query (miles < 100)
  // and it's `ownerId` field matches the user ID.
  final newCar = Car(ObjectId(), userId, 'Toyota', miles: 2);
  realm.add(newCar);
});

// The documentation does not currently have this code example in JavaScript.
// Please refer to the other languages or related pages for example code.

// Per the Device Sync permissions, users can only read and write data
// where the `Item.ownerId` property matches their own user ID.
val userId = user.id
val newItem = Item().apply {
    ownerId = userId
    itemName = "This item meets sync criteria"
    complexity = 3
}
syncRealm.write {
    // `newItem` is successfully written to the realm and synced to Atlas
    // because its data matches the subscription query (complexity <= 4)
    // and its `ownerId` field matches the user ID.
    copyToRealm(newItem)
}

// This write falls within the subscription query and complies
// with the Device Sync permissions, so this write should succeed.
do {
    let learnRealm = Item()
    learnRealm.ownerId = user.id
    learnRealm.itemName = "Learn Realm CRUD stuff"
    learnRealm.complexity = 3
    try realm.write {
        realm.add(learnRealm)
    }
} catch {
    print("Failed to write to realm: \(error.localizedDescription)")
}

// The documentation does not currently have this code example in TypeScript.
// Please refer to the other languages or related pages for example code.