Using Flutter to read a single record from SQFlite, checking for null

Question

I am getting a bit confused with Futures and nulls here. I have a table in sqflite called organisations, and I am trying to read from it a organisation by id. If not found return null, otherwise return a Organisation object.

import 'database_helper.dart';
import 'package:sqflite/sqflite.dart';

class Organisation {
  late int organisationId;
  late String name;

  Organisation(
      {
        required this.organisationId,
        required this.name,
      });


  Organisation.fromJson(Map<String, dynamic> json) {
    organisationId = json["organisationId"]!;
    name = json["name"];
  }


  Map<String, dynamic> toMap() {
    return {
      'organisation' : organisationId,
      'name': name,
    };
  }
}

Future<Organisation?> readOrganisationById(int orgId) async {
  final dbHelper = DatabaseHelper();
  final db = await dbHelper.database;

  final List<Map<String, dynamic>> maps = await db.rawQuery(
      "SELECT * FROM organisations WHERE id = ?", [orgId]);

  if (maps.isEmpty) {
    return null;
  } else {
    return Organisation(
        organisationId: maps[0]['organisationId'],
        name: maps[0]['name']
    );
  }
}

I am then trying to call this like this, but the code editor is telling me : The getter 'name' isn't defined for the type 'Future<Organisation?>

Future<Organisation?> org = readOrganisationById(organisationId);
if (org != null) {
  organisationName = org.name;
}

How should I call readOrganisationById and check for null?

Answer 1

In your code, you are doing:

Future<Organisation?> org = readOrganisationById(organisationId);

However, the above is wrong. Since it's a Future, you need to await it as follows (also, I changed the type):

final Organisation? org = await readOrganisationById(organisationId);
 if (org != null) {
    print(org.name);
  }