Refactored whole export/import methods in DataTransferService

assets/schema.json

@@ -0,0 +1,137 @@
+
+
+{
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "type": "object",
+  "properties": {
+    "games": {
+      "type": "array",
+      "items": [
+        {
+          "type": "object",
+          "properties": {
+            "id": {
+              "type": "string"
+            },
+            "name": {
+              "type": "string"
+            },
+            "players": {
+              "type": "null"
+            },
+            "group": {
+              "type": "null"
+            },
+            "winner": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "id",
+            "name",
+            "players",
+            "group",
+            "winner"
+          ]
+        }
+      ]
+    },
+    "groups": {
+      "type": "array",
+      "items": [
+        {
+          "type": "object",
+          "properties": {
+            "id": {
+              "type": "string"
+            },
+            "name": {
+              "type": "string"
+            },
+            "members": {
+              "type": "array",
+              "items": [
+                {
+                  "type": "object",
+                  "properties": {
+                    "id": {
+                      "type": "string"
+                    },
+                    "name": {
+                      "type": "string"
+                    }
+                  },
+                  "required": [
+                    "id",
+                    "name"
+                  ]
+                },
+                {
+                  "type": "object",
+                  "properties": {
+                    "id": {
+                      "type": "string"
+                    },
+                    "name": {
+                      "type": "string"
+                    }
+                  },
+                  "required": [
+                    "id",
+                    "name"
+                  ]
+                }
+              ]
+            }
+          },
+          "required": [
+            "id",
+            "name",
+            "members"
+          ]
+        }
+      ]
+    },
+    "players": {
+      "type": "array",
+      "items": [
+        {
+          "type": "object",
+          "properties": {
+            "id": {
+              "type": "string"
+            },
+            "name": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "id",
+            "name"
+          ]
+        },
+        {
+          "type": "object",
+          "properties": {
+            "id": {
+              "type": "string"
+            },
+            "name": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "id",
+            "name"
+          ]
+        }
+      ]
+    }
+  },
+  "required": [
+    "games",
+    "groups",
+    "players"
+  ]
+}
+

lib/data/dao/game_dao.dart

@@ -57,7 +57,7 @@ class GameDao extends DatabaseAccessor<AppDatabase> with _$GameDaoMixin {
         GameTableCompanion.insert(
           id: game.id,
           name: game.name,
-          winnerId: game.winner,
+          winnerId: Value(game.winner),
         ),
         mode: InsertMode.insertOrReplace,
       );
@@ -88,4 +88,12 @@ class GameDao extends DatabaseAccessor<AppDatabase> with _$GameDaoMixin {
     final result = await query.getSingleOrNull();
     return result != null;
   }
+
+  /// Deletes all games from the database.
+  /// Returns `true` if more than 0 rows were affected, otherwise `false`.
+  Future<bool> deleteAllGames() async {
+    final query = delete(gameTable);
+    final rowsAffected = await query.go();
+    return rowsAffected > 0;
+  }
 }

lib/data/dao/game_dao.g.dart

@@ -4,6 +4,5 @@ part of 'game_dao.dart';
 
 // ignore_for_file: type=lint
 mixin _$GameDaoMixin on DatabaseAccessor<AppDatabase> {
-  $PlayerTableTable get playerTable => attachedDatabase.playerTable;
   $GameTableTable get gameTable => attachedDatabase.gameTable;
 }

lib/data/dao/group_dao.dart

@@ -103,4 +103,12 @@ class GroupDao extends DatabaseAccessor<AppDatabase> with _$GroupDaoMixin {
     final result = await query.getSingleOrNull();
     return result != null;
   }
+
+  /// Deletes all groups from the database.
+  /// Returns `true` if more than 0 rows were affected, otherwise `false`.
+  Future<bool> deleteAllGroups() async {
+    final query = delete(groupTable);
+    final rowsAffected = await query.go();
+    return rowsAffected > 0;
+  }
 }

lib/data/dao/group_game_dao.g.dart

@@ -5,7 +5,6 @@ part of 'group_game_dao.dart';
 // ignore_for_file: type=lint
 mixin _$GroupGameDaoMixin on DatabaseAccessor<AppDatabase> {
   $GroupTableTable get groupTable => attachedDatabase.groupTable;
-  $PlayerTableTable get playerTable => attachedDatabase.playerTable;
   $GameTableTable get gameTable => attachedDatabase.gameTable;
   $GroupGameTableTable get groupGameTable => attachedDatabase.groupGameTable;
 }

lib/data/dao/player_dao.dart

@@ -70,4 +70,12 @@ class PlayerDao extends DatabaseAccessor<AppDatabase> with _$PlayerDaoMixin {
             .getSingle();
     return count ?? 0;
   }
+
+  /// Deletes all players from the database.
+  /// Returns `true` if more than 0 rows were affected, otherwise `false`.
+  Future<bool> deleteAllPlayers() async {
+    final query = delete(playerTable);
+    final rowsAffected = await query.go();
+    return rowsAffected > 0;
+  }
 }

lib/data/db/database.dart

@@ -40,6 +40,15 @@ class AppDatabase extends _$AppDatabase {
   @override
   int get schemaVersion => 1;
 
+  @override
+  MigrationStrategy get migration {
+    return MigrationStrategy(
+      beforeOpen: (details) async {
+        await customStatement('PRAGMA foreign_keys = ON');
+      },
+    );
+  }
+
   static QueryExecutor _openConnection() {
     return driftDatabase(
       name: 'gametracker_db',

lib/data/db/database.g.dart

@@ -444,12 +444,9 @@ class $GameTableTable extends GameTable
   late final GeneratedColumn<String> winnerId = GeneratedColumn<String>(
     'winner_id',
     aliasedName,
-    false,
+    true,
     type: DriftSqlType.string,
-    requiredDuringInsert: true,
-    defaultConstraints: GeneratedColumn.constraintIsAlways(
-      'REFERENCES player_table (id) ON DELETE CASCADE',
-    ),
+    requiredDuringInsert: false,
   );
   @override
   List<GeneratedColumn> get $columns => [id, name, winnerId];
@@ -483,8 +480,6 @@ class $GameTableTable extends GameTable
         _winnerIdMeta,
         winnerId.isAcceptableOrUnknown(data['winner_id']!, _winnerIdMeta),
       );
-    } else if (isInserting) {
-      context.missing(_winnerIdMeta);
     }
     return context;
   }
@@ -506,7 +501,7 @@ class $GameTableTable extends GameTable
       winnerId: attachedDatabase.typeMapping.read(
         DriftSqlType.string,
         data['${effectivePrefix}winner_id'],
-      )!,
+      ),
     );
   }
 
@@ -519,18 +514,16 @@ class $GameTableTable extends GameTable
 class GameTableData extends DataClass implements Insertable<GameTableData> {
   final String id;
   final String name;
-  final String winnerId;
-  const GameTableData({
-    required this.id,
-    required this.name,
-    required this.winnerId,
-  });
+  final String? winnerId;
+  const GameTableData({required this.id, required this.name, this.winnerId});
   @override
   Map<String, Expression> toColumns(bool nullToAbsent) {
     final map = <String, Expression>{};
     map['id'] = Variable<String>(id);
     map['name'] = Variable<String>(name);
+    if (!nullToAbsent || winnerId != null) {
       map['winner_id'] = Variable<String>(winnerId);
+    }
     return map;
   }
 
@@ -538,7 +531,9 @@ class GameTableData extends DataClass implements Insertable<GameTableData> {
     return GameTableCompanion(
       id: Value(id),
       name: Value(name),
-      winnerId: Value(winnerId),
+      winnerId: winnerId == null && nullToAbsent
+          ? const Value.absent()
+          : Value(winnerId),
     );
   }
 
@@ -550,7 +545,7 @@ class GameTableData extends DataClass implements Insertable<GameTableData> {
     return GameTableData(
       id: serializer.fromJson<String>(json['id']),
       name: serializer.fromJson<String>(json['name']),
-      winnerId: serializer.fromJson<String>(json['winnerId']),
+      winnerId: serializer.fromJson<String?>(json['winnerId']),
     );
   }
   @override
@@ -559,15 +554,18 @@ class GameTableData extends DataClass implements Insertable<GameTableData> {
     return <String, dynamic>{
       'id': serializer.toJson<String>(id),
       'name': serializer.toJson<String>(name),
-      'winnerId': serializer.toJson<String>(winnerId),
+      'winnerId': serializer.toJson<String?>(winnerId),
     };
   }
 
-  GameTableData copyWith({String? id, String? name, String? winnerId}) =>
-      GameTableData(
+  GameTableData copyWith({
+    String? id,
+    String? name,
+    Value<String?> winnerId = const Value.absent(),
+  }) => GameTableData(
     id: id ?? this.id,
     name: name ?? this.name,
-        winnerId: winnerId ?? this.winnerId,
+    winnerId: winnerId.present ? winnerId.value : this.winnerId,
   );
   GameTableData copyWithCompanion(GameTableCompanion data) {
     return GameTableData(
@@ -601,7 +599,7 @@ class GameTableData extends DataClass implements Insertable<GameTableData> {
 class GameTableCompanion extends UpdateCompanion<GameTableData> {
   final Value<String> id;
   final Value<String> name;
-  final Value<String> winnerId;
+  final Value<String?> winnerId;
   final Value<int> rowid;
   const GameTableCompanion({
     this.id = const Value.absent(),
@@ -612,11 +610,10 @@ class GameTableCompanion extends UpdateCompanion<GameTableData> {
   GameTableCompanion.insert({
     required String id,
     required String name,
-    required String winnerId,
+    this.winnerId = const Value.absent(),
     this.rowid = const Value.absent(),
   }) : id = Value(id),
-       name = Value(name),
-       winnerId = Value(winnerId);
+       name = Value(name);
   static Insertable<GameTableData> custom({
     Expression<String>? id,
     Expression<String>? name,
@@ -634,7 +631,7 @@ class GameTableCompanion extends UpdateCompanion<GameTableData> {
   GameTableCompanion copyWith({
     Value<String>? id,
     Value<String>? name,
-    Value<String>? winnerId,
+    Value<String?>? winnerId,
     Value<int>? rowid,
   }) {
     return GameTableCompanion(
@@ -1381,13 +1378,6 @@ abstract class _$AppDatabase extends GeneratedDatabase {
   ];
   @override
   StreamQueryUpdateRules get streamUpdateRules => const StreamQueryUpdateRules([
-    WritePropagation(
-      on: TableUpdateQuery.onTableName(
-        'player_table',
-        limitUpdateKind: UpdateKind.delete,
-      ),
-      result: [TableUpdate('game_table', kind: UpdateKind.delete)],
-    ),
     WritePropagation(
       on: TableUpdateQuery.onTableName(
         'player_table',
@@ -1450,24 +1440,6 @@ final class $$PlayerTableTableReferences
     extends BaseReferences<_$AppDatabase, $PlayerTableTable, PlayerTableData> {
   $$PlayerTableTableReferences(super.$_db, super.$_table, super.$_typedResult);
 
-  static MultiTypedResultKey<$GameTableTable, List<GameTableData>>
-  _gameTableRefsTable(_$AppDatabase db) => MultiTypedResultKey.fromTable(
-    db.gameTable,
-    aliasName: $_aliasNameGenerator(db.playerTable.id, db.gameTable.winnerId),
-  );
-
-  $$GameTableTableProcessedTableManager get gameTableRefs {
-    final manager = $$GameTableTableTableManager(
-      $_db,
-      $_db.gameTable,
-    ).filter((f) => f.winnerId.id.sqlEquals($_itemColumn<String>('id')!));
-
-    final cache = $_typedResult.readTableOrNull(_gameTableRefsTable($_db));
-    return ProcessedTableManager(
-      manager.$state.copyWith(prefetchedData: cache),
-    );
-  }
-
   static MultiTypedResultKey<$PlayerGroupTableTable, List<PlayerGroupTableData>>
   _playerGroupTableRefsTable(_$AppDatabase db) => MultiTypedResultKey.fromTable(
     db.playerGroupTable,
@@ -1534,31 +1506,6 @@ class $$PlayerTableTableFilterComposer
     builder: (column) => ColumnFilters(column),
   );
 
-  Expression<bool> gameTableRefs(
-    Expression<bool> Function($$GameTableTableFilterComposer f) f,
-  ) {
-    final $$GameTableTableFilterComposer composer = $composerBuilder(
-      composer: this,
-      getCurrentColumn: (t) => t.id,
-      referencedTable: $db.gameTable,
-      getReferencedColumn: (t) => t.winnerId,
-      builder:
-          (
-            joinBuilder, {
-            $addJoinBuilderToRootComposer,
-            $removeJoinBuilderFromRootComposer,
-          }) => $$GameTableTableFilterComposer(
-            $db: $db,
-            $table: $db.gameTable,
-            $addJoinBuilderToRootComposer: $addJoinBuilderToRootComposer,
-            joinBuilder: joinBuilder,
-            $removeJoinBuilderFromRootComposer:
-                $removeJoinBuilderFromRootComposer,
-          ),
-    );
-    return f(composer);
-  }
-
   Expression<bool> playerGroupTableRefs(
     Expression<bool> Function($$PlayerGroupTableTableFilterComposer f) f,
   ) {
@@ -1645,31 +1592,6 @@ class $$PlayerTableTableAnnotationComposer
   GeneratedColumn<String> get name =>
       $composableBuilder(column: $table.name, builder: (column) => column);
 
-  Expression<T> gameTableRefs<T extends Object>(
-    Expression<T> Function($$GameTableTableAnnotationComposer a) f,
-  ) {
-    final $$GameTableTableAnnotationComposer composer = $composerBuilder(
-      composer: this,
-      getCurrentColumn: (t) => t.id,
-      referencedTable: $db.gameTable,
-      getReferencedColumn: (t) => t.winnerId,
-      builder:
-          (
-            joinBuilder, {
-            $addJoinBuilderToRootComposer,
-            $removeJoinBuilderFromRootComposer,
-          }) => $$GameTableTableAnnotationComposer(
-            $db: $db,
-            $table: $db.gameTable,
-            $addJoinBuilderToRootComposer: $addJoinBuilderToRootComposer,
-            joinBuilder: joinBuilder,
-            $removeJoinBuilderFromRootComposer:
-                $removeJoinBuilderFromRootComposer,
-          ),
-    );
-    return f(composer);
-  }
-
   Expression<T> playerGroupTableRefs<T extends Object>(
     Expression<T> Function($$PlayerGroupTableTableAnnotationComposer a) f,
   ) {
@@ -1735,7 +1657,6 @@ class $$PlayerTableTableTableManager
           (PlayerTableData, $$PlayerTableTableReferences),
           PlayerTableData,
           PrefetchHooks Function({
-            bool gameTableRefs,
             bool playerGroupTableRefs,
             bool playerGameTableRefs,
           })
@@ -1773,42 +1694,16 @@ class $$PlayerTableTableTableManager
               )
               .toList(),
           prefetchHooksCallback:
-              ({
-                gameTableRefs = false,
-                playerGroupTableRefs = false,
-                playerGameTableRefs = false,
-              }) {
+              ({playerGroupTableRefs = false, playerGameTableRefs = false}) {
                 return PrefetchHooks(
                   db: db,
                   explicitlyWatchedTables: [
-                    if (gameTableRefs) db.gameTable,
                     if (playerGroupTableRefs) db.playerGroupTable,
                     if (playerGameTableRefs) db.playerGameTable,
                   ],
                   addJoins: null,
                   getPrefetchedDataCallback: (items) async {
                     return [
-                      if (gameTableRefs)
-                        await $_getPrefetchedData<
-                          PlayerTableData,
-                          $PlayerTableTable,
-                          GameTableData
-                        >(
-                          currentTable: table,
-                          referencedTable: $$PlayerTableTableReferences
-                              ._gameTableRefsTable(db),
-                          managerFromTypedResult: (p0) =>
-                              $$PlayerTableTableReferences(
-                                db,
-                                table,
-                                p0,
-                              ).gameTableRefs,
-                          referencedItemsForCurrentItem:
-                              (item, referencedItems) => referencedItems.where(
-                                (e) => e.winnerId == item.id,
-                              ),
-                          typedResults: items,
-                        ),
                       if (playerGroupTableRefs)
                         await $_getPrefetchedData<
                           PlayerTableData,
@@ -1872,7 +1767,6 @@ typedef $$PlayerTableTableProcessedTableManager =
       (PlayerTableData, $$PlayerTableTableReferences),
       PlayerTableData,
       PrefetchHooks Function({
-        bool gameTableRefs,
         bool playerGroupTableRefs,
         bool playerGameTableRefs,
       })
@@ -2227,14 +2121,14 @@ typedef $$GameTableTableCreateCompanionBuilder =
     GameTableCompanion Function({
       required String id,
       required String name,
-      required String winnerId,
+      Value<String?> winnerId,
       Value<int> rowid,
     });
 typedef $$GameTableTableUpdateCompanionBuilder =
     GameTableCompanion Function({
       Value<String> id,
       Value<String> name,
-      Value<String> winnerId,
+      Value<String?> winnerId,
       Value<int> rowid,
     });
 
@@ -2242,25 +2136,6 @@ final class $$GameTableTableReferences
     extends BaseReferences<_$AppDatabase, $GameTableTable, GameTableData> {
   $$GameTableTableReferences(super.$_db, super.$_table, super.$_typedResult);
 
-  static $PlayerTableTable _winnerIdTable(_$AppDatabase db) =>
-      db.playerTable.createAlias(
-        $_aliasNameGenerator(db.gameTable.winnerId, db.playerTable.id),
-      );
-
-  $$PlayerTableTableProcessedTableManager get winnerId {
-    final $_column = $_itemColumn<String>('winner_id')!;
-
-    final manager = $$PlayerTableTableTableManager(
-      $_db,
-      $_db.playerTable,
-    ).filter((f) => f.id.sqlEquals($_column));
-    final item = $_typedResult.readTableOrNull(_winnerIdTable($_db));
-    if (item == null) return manager;
-    return ProcessedTableManager(
-      manager.$state.copyWith(prefetchedData: [item]),
-    );
-  }
-
   static MultiTypedResultKey<$PlayerGameTableTable, List<PlayerGameTableData>>
   _playerGameTableRefsTable(_$AppDatabase db) => MultiTypedResultKey.fromTable(
     db.playerGameTable,
@@ -2319,28 +2194,10 @@ class $$GameTableTableFilterComposer
     builder: (column) => ColumnFilters(column),
   );
 
-  $$PlayerTableTableFilterComposer get winnerId {
-    final $$PlayerTableTableFilterComposer composer = $composerBuilder(
-      composer: this,
-      getCurrentColumn: (t) => t.winnerId,
-      referencedTable: $db.playerTable,
-      getReferencedColumn: (t) => t.id,
-      builder:
-          (
-            joinBuilder, {
-            $addJoinBuilderToRootComposer,
-            $removeJoinBuilderFromRootComposer,
-          }) => $$PlayerTableTableFilterComposer(
-            $db: $db,
-            $table: $db.playerTable,
-            $addJoinBuilderToRootComposer: $addJoinBuilderToRootComposer,
-            joinBuilder: joinBuilder,
-            $removeJoinBuilderFromRootComposer:
-                $removeJoinBuilderFromRootComposer,
-          ),
+  ColumnFilters<String> get winnerId => $composableBuilder(
+    column: $table.winnerId,
+    builder: (column) => ColumnFilters(column),
   );
-    return composer;
-  }
 
   Expression<bool> playerGameTableRefs(
     Expression<bool> Function($$PlayerGameTableTableFilterComposer f) f,
@@ -2412,28 +2269,10 @@ class $$GameTableTableOrderingComposer
     builder: (column) => ColumnOrderings(column),
   );
 
-  $$PlayerTableTableOrderingComposer get winnerId {
-    final $$PlayerTableTableOrderingComposer composer = $composerBuilder(
-      composer: this,
-      getCurrentColumn: (t) => t.winnerId,
-      referencedTable: $db.playerTable,
-      getReferencedColumn: (t) => t.id,
-      builder:
-          (
-            joinBuilder, {
-            $addJoinBuilderToRootComposer,
-            $removeJoinBuilderFromRootComposer,
-          }) => $$PlayerTableTableOrderingComposer(
-            $db: $db,
-            $table: $db.playerTable,
-            $addJoinBuilderToRootComposer: $addJoinBuilderToRootComposer,
-            joinBuilder: joinBuilder,
-            $removeJoinBuilderFromRootComposer:
-                $removeJoinBuilderFromRootComposer,
-          ),
+  ColumnOrderings<String> get winnerId => $composableBuilder(
+    column: $table.winnerId,
+    builder: (column) => ColumnOrderings(column),
   );
-    return composer;
-  }
 }
 
 class $$GameTableTableAnnotationComposer
@@ -2451,28 +2290,8 @@ class $$GameTableTableAnnotationComposer
   GeneratedColumn<String> get name =>
       $composableBuilder(column: $table.name, builder: (column) => column);
 
-  $$PlayerTableTableAnnotationComposer get winnerId {
-    final $$PlayerTableTableAnnotationComposer composer = $composerBuilder(
-      composer: this,
-      getCurrentColumn: (t) => t.winnerId,
-      referencedTable: $db.playerTable,
-      getReferencedColumn: (t) => t.id,
-      builder:
-          (
-            joinBuilder, {
-            $addJoinBuilderToRootComposer,
-            $removeJoinBuilderFromRootComposer,
-          }) => $$PlayerTableTableAnnotationComposer(
-            $db: $db,
-            $table: $db.playerTable,
-            $addJoinBuilderToRootComposer: $addJoinBuilderToRootComposer,
-            joinBuilder: joinBuilder,
-            $removeJoinBuilderFromRootComposer:
-                $removeJoinBuilderFromRootComposer,
-          ),
-    );
-    return composer;
-  }
+  GeneratedColumn<String> get winnerId =>
+      $composableBuilder(column: $table.winnerId, builder: (column) => column);
 
   Expression<T> playerGameTableRefs<T extends Object>(
     Expression<T> Function($$PlayerGameTableTableAnnotationComposer a) f,
@@ -2539,7 +2358,6 @@ class $$GameTableTableTableManager
           (GameTableData, $$GameTableTableReferences),
           GameTableData,
           PrefetchHooks Function({
-            bool winnerId,
             bool playerGameTableRefs,
             bool groupGameTableRefs,
           })
@@ -2559,7 +2377,7 @@ class $$GameTableTableTableManager
               ({
                 Value<String> id = const Value.absent(),
                 Value<String> name = const Value.absent(),
-                Value<String> winnerId = const Value.absent(),
+                Value<String?> winnerId = const Value.absent(),
                 Value<int> rowid = const Value.absent(),
               }) => GameTableCompanion(
                 id: id,
@@ -2571,7 +2389,7 @@ class $$GameTableTableTableManager
               ({
                 required String id,
                 required String name,
-                required String winnerId,
+                Value<String?> winnerId = const Value.absent(),
                 Value<int> rowid = const Value.absent(),
               }) => GameTableCompanion.insert(
                 id: id,
@@ -2588,49 +2406,14 @@ class $$GameTableTableTableManager
               )
               .toList(),
           prefetchHooksCallback:
-              ({
-                winnerId = false,
-                playerGameTableRefs = false,
-                groupGameTableRefs = false,
-              }) {
+              ({playerGameTableRefs = false, groupGameTableRefs = false}) {
                 return PrefetchHooks(
                   db: db,
                   explicitlyWatchedTables: [
                     if (playerGameTableRefs) db.playerGameTable,
                     if (groupGameTableRefs) db.groupGameTable,
                   ],
-                  addJoins:
-                      <
-                        T extends TableManagerState<
-                          dynamic,
-                          dynamic,
-                          dynamic,
-                          dynamic,
-                          dynamic,
-                          dynamic,
-                          dynamic,
-                          dynamic,
-                          dynamic,
-                          dynamic,
-                          dynamic
-                        >
-                      >(state) {
-                        if (winnerId) {
-                          state =
-                              state.withJoin(
-                                    currentTable: table,
-                                    currentColumn: table.winnerId,
-                                    referencedTable: $$GameTableTableReferences
-                                        ._winnerIdTable(db),
-                                    referencedColumn: $$GameTableTableReferences
-                                        ._winnerIdTable(db)
-                                        .id,
-                                  )
-                                  as T;
-                        }
-
-                        return state;
-                      },
+                  addJoins: null,
                   getPrefetchedDataCallback: (items) async {
                     return [
                       if (playerGameTableRefs)
@@ -2696,7 +2479,6 @@ typedef $$GameTableTableProcessedTableManager =
       (GameTableData, $$GameTableTableReferences),
       GameTableData,
       PrefetchHooks Function({
-        bool winnerId,
         bool playerGameTableRefs,
         bool groupGameTableRefs,
       })

lib/data/db/tables/game_table.dart

@@ -1,11 +1,9 @@
 import 'package:drift/drift.dart';
-import 'package:game_tracker/data/db/tables/player_table.dart';
 
 class GameTable extends Table {
   TextColumn get id => text()();
   TextColumn get name => text()();
-  TextColumn get winnerId =>
-      text().references(PlayerTable, #id, onDelete: KeyAction.cascade)();
+  late final winnerId = text().nullable()();
 
   @override
   Set<Column<Object>> get primaryKey => {id};

lib/data/dto/game.dart

@@ -7,18 +7,34 @@ class Game {
   final String name;
   final List<Player>? players;
   final Group? group;
-  final String winner;
+  final String? winner;
 
-  Game({
-    String? id,
-    required this.name,
-    this.players,
-    this.group,
-    this.winner = '',
-  }) : id = id ?? const Uuid().v4();
+  Game({String? id, required this.name, this.players, this.group, this.winner})
+    : id = id ?? const Uuid().v4();
 
   @override
   String toString() {
     return 'Game{\n\tid: $id,\n\tname: $name,\n\tplayers: $players,\n\tgroup: $group,\n\twinner: $winner\n}';
   }
+
+  /// Creates a Game instance from a JSON object.
+  Game.fromJson(Map<String, dynamic> json)
+    : id = json['id'],
+      name = json['name'],
+      players = json['players'] != null
+          ? (json['players'] as List)
+                .map((playerJson) => Player.fromJson(playerJson))
+                .toList()
+          : null,
+      group = json['group'] != null ? Group.fromJson(json['group']) : null,
+      winner = json['winner'] ?? '';
+
+  /// Converts the Game instance to a JSON object.
+  Map<String, dynamic> toJson() => {
+    'id': id,
+    'name': name,
+    'players': players?.map((player) => player.toJson()).toList(),
+    'group': group?.toJson(),
+    'winner': winner,
+  };
 }

lib/data/dto/group.dart

@@ -13,4 +13,19 @@ class Group {
   String toString() {
     return 'Group{id: $id, name: $name,members: $members}';
   }
+
+  /// Creates a Group instance from a JSON object.
+  Group.fromJson(Map<String, dynamic> json)
+    : id = json['id'],
+      name = json['name'],
+      members = (json['members'] as List)
+          .map((memberJson) => Player.fromJson(memberJson))
+          .toList();
+
+  /// Converts the Group instance to a JSON object.
+  Map<String, dynamic> toJson() => {
+    'id': id,
+    'name': name,
+    'members': members.map((member) => member.toJson()).toList(),
+  };
 }

lib/data/dto/player.dart

@@ -10,4 +10,12 @@ class Player {
   String toString() {
     return 'Player{id: $id,name: $name}';
   }
+
+  /// Creates a Player instance from a JSON object.
+  Player.fromJson(Map<String, dynamic> json)
+    : id = json['id'],
+      name = json['name'];
+
+  /// Converts the Player instance to a JSON object.
+  Map<String, dynamic> toJson() => {'id': id, 'name': name};
 }

lib/presentation/views/main_menu/settings_view.dart

@@ -1,10 +1,41 @@
+import 'dart:convert';
+
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 import 'package:game_tracker/core/custom_theme.dart';
 import 'package:game_tracker/presentation/widgets/tiles/settings_list_tile.dart';
+import 'package:game_tracker/services/data_transfer_service.dart';
+import 'package:json_schema/json_schema.dart';
 
-class SettingsView extends StatelessWidget {
+class SettingsView extends StatefulWidget {
   const SettingsView({super.key});
 
+  @override
+  State<SettingsView> createState() => _SettingsViewState();
+
+  static Future<bool> validateJsonSchema(String jsonString) async {
+    final String schemaString;
+
+    schemaString = await rootBundle.loadString('assets/schema.json');
+
+    try {
+      final schema = JsonSchema.create(json.decode(schemaString));
+      final jsonData = json.decode(jsonString);
+      final result = schema.validate(jsonData);
+
+      if (result.isValid) {
+        return true;
+      }
+      return false;
+    } catch (e, stack) {
+      print('[validateJsonSchema] $e');
+      print(stack);
+      return false;
+    }
+  }
+}
+
+class _SettingsViewState extends State<SettingsView> {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -39,41 +70,30 @@ class SettingsView extends StatelessWidget {
                       ),
                     ),
                   ),
-
                   SettingsListTile(
-                    title: 'Export Data',
+                    title: 'Export data',
                     icon: Icons.upload_outlined,
                     suffixWidget: const Icon(Icons.arrow_forward_ios, size: 16),
-                    onPressed: () => exportData(),
+                    onPressed: () async {
+                      final String json =
+                          await DataTransferService.getAppDataAsJson(context);
+                      await DataTransferService.exportData(
+                        json,
+                        'exported_data',
+                      );
+                    },
                   ),
                   SettingsListTile(
-                    title: 'Import Data',
+                    title: 'Import data',
                     icon: Icons.download_outlined,
                     suffixWidget: const Icon(Icons.arrow_forward_ios, size: 16),
-                    onPressed: () => importData(),
-                  ),
-                  const Padding(
-                    padding: EdgeInsets.symmetric(horizontal: 24, vertical: 10),
-                    child: Text(
-                      textAlign: TextAlign.start,
-                      'Example Headline',
-                      style: TextStyle(
-                        fontSize: 22,
-                        fontWeight: FontWeight.bold,
-                      ),
-                    ),
+                    onPressed: () => DataTransferService.importData(context),
                   ),
                   SettingsListTile(
-                    title: 'Example Tile',
-                    icon: Icons.upload_outlined,
-                    suffixWidget: const Icon(Icons.arrow_forward_ios, size: 16),
-                    onPressed: () => print('Example Tile'),
-                  ),
-                  SettingsListTile(
-                    title: 'Example Tile',
+                    title: 'Delete all data',
                     icon: Icons.download_outlined,
                     suffixWidget: const Icon(Icons.arrow_forward_ios, size: 16),
-                    onPressed: () => print('Example Tile'),
+                    onPressed: () => DataTransferService.deleteAllData(context),
                   ),
                 ],
               ),
@@ -81,10 +101,4 @@ class SettingsView extends StatelessWidget {
       ),
     );
   }
-
-  // TODO: Implement export functionality
-  void exportData() {}
-
-  // TODO: Implement import functionality
-  void importData() {}
 }

lib/services/data_transfer_service.dart

@@ -0,0 +1,135 @@
+import 'dart:convert';
+import 'dart:io';
+import 'dart:typed_data';
+
+import 'package:file_picker/file_picker.dart';
+import 'package:flutter/material.dart';
+import 'package:game_tracker/data/db/database.dart';
+import 'package:game_tracker/data/dto/game.dart';
+import 'package:game_tracker/data/dto/group.dart';
+import 'package:game_tracker/data/dto/player.dart';
+import 'package:game_tracker/presentation/views/main_menu/settings_view.dart';
+import 'package:provider/provider.dart';
+
+class DataTransferService {
+  /// Deletes all data from the database.
+  static Future<void> deleteAllData(BuildContext context) async {
+    final db = Provider.of<AppDatabase>(context, listen: false);
+    await db.gameDao.deleteAllGames();
+    await db.groupDao.deleteAllGroups();
+    await db.playerDao.deleteAllPlayers();
+    print('[deleteAllData] All data deleted');
+  }
+
+  static Future<String> getAppDataAsJson(BuildContext context) async {
+    final db = Provider.of<AppDatabase>(context, listen: false);
+    final games = await db.gameDao.getAllGames();
+    final groups = await db.groupDao.getAllGroups();
+    final players = await db.playerDao.getAllPlayers();
+
+    // Construct a JSON representation of the data
+    final Map<String, dynamic> jsonMap = {
+      'games': games.map((game) => game.toJson()).toList(),
+      'groups': groups.map((group) => group.toJson()).toList(),
+      'players': players.map((player) => player.toJson()).toList(),
+    };
+
+    return json.encode(jsonMap);
+  }
+
+  /// Exports the given JSON string to a file with the specified name.
+  static Future<bool> exportData(String jsonString, String fileName) async {
+    try {
+      final bytes = Uint8List.fromList(utf8.encode(jsonString));
+      await FilePicker.platform.saveFile(
+        fileName: '$fileName.json',
+        bytes: bytes,
+      );
+      return true;
+    } catch (e, stack) {
+      print('[exportData] $e');
+      print(stack);
+      return false;
+    }
+  }
+
+  /// Imports data from a selected JSON file into the database.
+  static Future<void> importData(BuildContext context) async {
+    final db = Provider.of<AppDatabase>(context, listen: false);
+
+    final path = await FilePicker.platform.pickFiles(
+      type: FileType.custom,
+      allowedExtensions: ['json'],
+    );
+
+    if (path == null) {
+      print('[importData] No file selected');
+      return;
+    }
+
+    try {
+      final jsonString = await _readFileContent(path.files.single);
+
+      if (await SettingsView.validateJsonSchema(jsonString)) {
+        final Map<String, dynamic> jsonData =
+            json.decode(jsonString) as Map<String, dynamic>;
+
+        final List<dynamic>? gamesJson = jsonData['games'] as List<dynamic>?;
+        final List<dynamic>? groupsJson = jsonData['groups'] as List<dynamic>?;
+        final List<dynamic>? playersJson =
+            jsonData['players'] as List<dynamic>?;
+
+        final List<Game> importedGames =
+            gamesJson
+                ?.map((g) => Game.fromJson(g as Map<String, dynamic>))
+                .toList() ??
+            [];
+        final List<Group> importedGroups =
+            groupsJson
+                ?.map((g) => Group.fromJson(g as Map<String, dynamic>))
+                .toList() ??
+            [];
+        final List<Player> importedPlayers =
+            playersJson
+                ?.map((p) => Player.fromJson(p as Map<String, dynamic>))
+                .toList() ??
+            [];
+
+        for (Player player in importedPlayers) {
+          await db.playerDao.addPlayer(player: player);
+        }
+
+        for (Group group in importedGroups) {
+          await db.groupDao.addGroup(group: group);
+        }
+
+        for (Game game in importedGames) {
+          await db.gameDao.addGame(game: game);
+        }
+      } else {
+        print('[importData] Invalid JSON schema');
+        return;
+      }
+      print('[importData] Data imported successfully');
+      return;
+    } on FormatException catch (e, stack) {
+      print('[importData] FormatException');
+      print('[importData] $e');
+      print(stack);
+      return;
+    } on Exception catch (e, stack) {
+      print('[importData] Exception');
+      print('[importData] $e');
+      print(stack);
+      return;
+    }
+  }
+
+  /// Helper method to read file content from either bytes or path
+  static Future<String> _readFileContent(PlatformFile file) async {
+    if (file.bytes != null) return utf8.decode(file.bytes!);
+    if (file.path != null) return await File(file.path!).readAsString();
+
+    throw Exception('Die Datei hat keinen lesbaren Inhalt');
+  }
+}

pubspec.yaml

@@ -20,6 +20,9 @@ dependencies:
   provider: ^6.1.5
   skeletonizer: ^2.1.0+1
   uuid: ^4.5.2
+  file_picker: ^10.3.6
+  json_schema: ^5.2.2
+  file_saver: ^0.3.1
 
 dev_dependencies:
   flutter_test:
@@ -30,3 +33,5 @@ dev_dependencies:
 
 flutter:
   uses-material-design: true
+  assets:
+    - assets/schema.json