Null safety

lib/common/appstart/localization_initialize.dart

@@ -9,8 +9,8 @@ import 'package:kiwi/kiwi.dart';
 /// correct language
 ///
 class LocalizationInitialize {
-  PreferencesProvider _preferencesProvider;
-  String _languageCode;
+  PreferencesProvider? _preferencesProvider;
+  String? _languageCode;
 
   ///
   /// Initialize the localization using the provided language code

lib/common/data/database_access.dart

@@ -4,15 +4,12 @@ import 'package:sqflite/sqflite.dart';
 
 class DatabaseAccess {
   static const String _databaseName = "Database.db";
-  static Database _databaseInstance;
+  static Database? _databaseInstance;
 
   static const String idColumnName = "id";
 
   Future<Database> get _database async {
-    if (_databaseInstance != null) return _databaseInstance;
-
-    _databaseInstance = await _initDatabase();
-    return _databaseInstance;
+    return _databaseInstance ??= await _initDatabase();
   }
 
   Future<Database> _initDatabase() async {
@@ -60,19 +57,20 @@ class DatabaseAccess {
   }
 
   Future<List<Map<String, dynamic>>> queryRows(String table,
-      {bool distinct,
-      List<String> columns,
-      String where,
-      List<dynamic> whereArgs,
-      String groupBy,
-      String having,
-      String orderBy,
-      int limit,
-      int offset}) async {
+      {bool? distinct,
+      List<String>? columns,
+      String? where,
+      List<dynamic>? whereArgs,
+      String? groupBy,
+      String? having,
+      String? orderBy,
+      int? limit,
+      int? offset}) async {
     Database db = await _database;
 
+    // TODO: [Leptopoda] is there a reason this is done? or at maybe use whereArgs.removeWhere()
     for (int i = 0; i < (whereArgs?.length ?? 0); i++) {
-      whereArgs[i] = whereArgs[i] ?? "";
+      whereArgs![i] = whereArgs[i] ?? "";
     }
 
     return await db.query(
@@ -89,33 +87,33 @@ class DatabaseAccess {
     );
   }
 
-  Future<int> queryRowCount(String table) async {
+  Future<int?> queryRowCount(String table) async {
     Database db = await _database;
     return Sqflite.firstIntValue(
         await db.rawQuery('SELECT COUNT(*) FROM $table'));
   }
 
-  Future<int> queryAggregator(String query, List<dynamic> arguments) async {
+  Future<int?> queryAggregator(String query, List<dynamic> arguments) async {
     Database db = await _database;
     return Sqflite.firstIntValue(await db.rawQuery(query, arguments));
   }
 
   Future<int> update(String table, Map<String, dynamic> row) async {
     Database db = await _database;
-    int id = row[idColumnName];
+    int? id = row[idColumnName];
     return await db
         .update(table, row, where: '$idColumnName = ?', whereArgs: [id]);
   }
 
-  Future<int> delete(String table, int id) async {
+  Future<int> delete(String table, int? id) async {
     Database db = await _database;
     return await db.delete(table, where: '$idColumnName = ?', whereArgs: [id]);
   }
 
   Future<int> deleteWhere(
     String table, {
-    String where,
-    List<dynamic> whereArgs,
+    String? where,
+    List<dynamic>? whereArgs,
   }) async {
     Database db = await _database;
     return await db.delete(

lib/common/data/database_entity.dart

@@ -1,4 +1,4 @@
 abstract class DatabaseEntity {
   Map<String, dynamic> toMap();
-  void fromMap(Map<String, dynamic> map);
+  fromMap(Map<String, dynamic> map);
 }

lib/common/data/database_path_provider.dart

@@ -2,7 +2,7 @@ import 'dart:io';
 
 import 'package:path_provider/path_provider.dart';
 import 'package:path/path.dart';
-import 'package:ios_app_group/ios_app_group.dart';
+import 'package:app_group_directory/app_group_directory.dart';
 
 Future<String> getDatabasePath(String databaseName) async {
   Directory documentsDirectory = await getApplicationDocumentsDirectory();
@@ -24,12 +24,13 @@ Future<String> _getiOSDatabasePathAndMigrate(
   // it must be saved in a group shared between the app module and the widget
   // module. "Migration" means that the database at the old path gets
   // copied to the new path
+  assert(Platform.isIOS);
 
-  var groupDirectory = await IosAppGroup.getAppGroupDirectory(
+  Directory? groupDirectory = await AppGroupDirectory.getAppGroupDirectory(
     'group.de.bennik2000.dhbwstudentapp',
   );
 
-  var newPath = join(groupDirectory.path, databaseName);
+  var newPath = join(groupDirectory!.path, databaseName);
 
   var migrateSuccess = await _migrateOldDatabase(oldPath, newPath);
 

lib/common/data/preferences/app_theme_enum.dart

@@ -1,9 +1,4 @@
-
 ///
 /// Enum which holds the possible themes the app can be displayed in
 ///
-enum AppTheme {
-  Dark,
-  Light,
-  System
-}
+enum AppTheme { Dark, Light, System }

lib/common/data/preferences/preferences_access.dart

@@ -17,32 +17,26 @@ class PreferencesAccess {
       case int:
         await prefs.setInt(key, value as int);
         return;
+      default:
+        throw InvalidValueTypeException(T);
     }
-
-    throw InvalidValueTypeException(T);
   }
 
-  Future<T> get<T>(String key) async {
+  Future<T?> get<T>(String key) async {
     final SharedPreferences prefs = await SharedPreferences.getInstance();
 
-    T value;
-
     switch (T) {
       case bool:
-        value = prefs.getBool(key) as T;
-        break;
+        return prefs.getBool(key) as T?;
       case String:
-        value = prefs.getString(key) as T;
-        break;
+        return prefs.getString(key) as T?;
       case double:
-        value = prefs.getDouble(key) as T;
-        break;
+        return prefs.getDouble(key) as T?;
       case int:
-        value = prefs.getInt(key) as T;
-        break;
+        return prefs.getInt(key) as T?;
+      default:
+        return null;
     }
-
-    return value;
   }
 }