Iterable map getters

hive/lib/src/box/box.dart

@@ -33,9 +33,27 @@ abstract class Box<E> implements BoxBase<E> {
   /// exist.
   E? get(dynamic key, {E? defaultValue});
 
+  /// Read the given [key] and cast the value to [List<T>]
+  List<T>? getList<T>(dynamic key, {List<T>? defaultValue});
+
+  /// Read the given [key] and cast the value to [Set<T>]
+  Set<T>? getSet<T>(dynamic key, {Set<T>? defaultValue});
+
+  /// Read the given [key] and cast the value to [Map<K, V>]
+  Map<K, V>? getMap<K, V>(dynamic key, {Map<K, V>? defaultValue});
+
   /// Returns the value associated with the n-th key.
   E? getAt(int index);
 
+  /// Read the value at the given [index] and cast the value to [List<T>]
+  List<T>? getListAt<T>(int index, {List<T>? defaultValue});
+
+  /// Read the value at the given [index] and cast the value to [Set<T>]
+  Set<T>? getSetAt<T>(int index, {Set<T>? defaultValue});
+
+  /// Read the value at the given [index] and cast the value to [Map<K, V>]
+  Map<K, V>? getMapAt<K, V>(int index, {Map<K, V>? defaultValue});
+
   /// Returns a map which contains all key - value pairs of the box.
   Map<dynamic, E> toMap();
 }

hive/lib/src/box/box_impl.dart

@@ -4,6 +4,7 @@ import 'package:hive_ce/hive.dart';
 import 'package:hive_ce/src/binary/frame.dart';
 import 'package:hive_ce/src/box/box_base_impl.dart';
 import 'package:hive_ce/src/object/hive_object.dart';
+import 'package:hive_ce/src/util/type_utils.dart';
 
 /// Not part of public API
 class BoxImpl<E> extends BoxBaseImpl<E> implements Box<E> {
@@ -49,13 +50,37 @@ class BoxImpl<E> extends BoxBaseImpl<E> implements Box<E> {
     }
   }
 
+  @override
+  List<T>? getList<T>(dynamic key, {List<T>? defaultValue}) =>
+      castList(get(key), defaultValue: defaultValue);
+
+  @override
+  Set<T>? getSet<T>(dynamic key, {Set<T>? defaultValue}) =>
+      castSet(get(key), defaultValue: defaultValue);
+
+  @override
+  Map<K, V>? getMap<K, V>(dynamic key, {Map<K, V>? defaultValue}) =>
+      castMap(get(key), defaultValue: defaultValue);
+
   @override
   E? getAt(int index) {
     checkOpen();
 
     return keystore.getAt(index)?.value as E?;
   }
 
+  @override
+  List<T>? getListAt<T>(int index, {List<T>? defaultValue}) =>
+      castList(getAt(index), defaultValue: defaultValue);
+
+  @override
+  Set<T>? getSetAt<T>(int index, {Set<T>? defaultValue}) =>
+      castSet(getAt(index), defaultValue: defaultValue);
+
+  @override
+  Map<K, V>? getMapAt<K, V>(int index, {Map<K, V>? defaultValue}) =>
+      castMap(getAt(index), defaultValue: defaultValue);
+
   @override
   Future<void> putAll(Map<dynamic, E> kvPairs) {
     final frames = <Frame>[];

hive/lib/src/box/lazy_box.dart

@@ -10,6 +10,24 @@ abstract class LazyBox<E> extends BoxBase<E> {
   /// exist.
   Future<E?> get(dynamic key, {E? defaultValue});
 
+  /// Read the given [key] and cast the value to [List<T>]
+  Future<List<T>?> getList<T>(dynamic key, {List<T>? defaultValue});
+
+  /// Read the given [key] and cast the value to [Set<T>]
+  Future<Set<T>?> getSet<T>(dynamic key, {Set<T>? defaultValue});
+
+  /// Read the given [key] and cast the value to [Map<K, V>]
+  Future<Map<K, V>?> getMap<K, V>(dynamic key, {Map<K, V>? defaultValue});
+
   /// Returns the value associated with the n-th key.
   Future<E?> getAt(int index);
+
+  /// Read the value at the given [index] and cast the value to [List<T>]
+  Future<List<T>?> getListAt<T>(int index, {List<T>? defaultValue});
+
+  /// Read the value at the given [index] and cast the value to [Set<T>]
+  Future<Set<T>?> getSetAt<T>(int index, {Set<T>? defaultValue});
+
+  /// Read the value at the given [index] and cast the value to [Map<K, V>]
+  Future<Map<K, V>?> getMapAt<K, V>(int index, {Map<K, V>? defaultValue});
 }

hive/lib/src/box/lazy_box_impl.dart

@@ -2,6 +2,7 @@ import 'package:hive_ce/hive.dart';
 import 'package:hive_ce/src/binary/frame.dart';
 import 'package:hive_ce/src/box/box_base_impl.dart';
 import 'package:hive_ce/src/object/hive_object.dart';
+import 'package:hive_ce/src/util/type_utils.dart';
 
 /// Not part of public API
 class LazyBoxImpl<E> extends BoxBaseImpl<E> implements LazyBox<E> {
@@ -38,11 +39,41 @@ class LazyBoxImpl<E> extends BoxBaseImpl<E> implements LazyBox<E> {
     }
   }
 
+  @override
+  Future<List<T>?> getList<T>(dynamic key, {List<T>? defaultValue}) async =>
+      castList(await get(key), defaultValue: defaultValue);
+
+  @override
+  Future<Set<T>?> getSet<T>(dynamic key, {Set<T>? defaultValue}) async =>
+      castSet(await get(key), defaultValue: defaultValue);
+
+  @override
+  Future<Map<K, V>?> getMap<K, V>(
+    dynamic key, {
+    Map<K, V>? defaultValue,
+  }) async =>
+      castMap(await get(key), defaultValue: defaultValue);
+
   @override
   Future<E?> getAt(int index) {
     return get(keystore.keyAt(index));
   }
 
+  @override
+  Future<List<T>?> getListAt<T>(int index, {List<T>? defaultValue}) async =>
+      castList(await getAt(index), defaultValue: defaultValue);
+
+  @override
+  Future<Set<T>?> getSetAt<T>(int index, {Set<T>? defaultValue}) async =>
+      castSet(await getAt(index), defaultValue: defaultValue);
+
+  @override
+  Future<Map<K, V>?> getMapAt<K, V>(
+    int index, {
+    Map<K, V>? defaultValue,
+  }) async =>
+      castMap(await getAt(index), defaultValue: defaultValue);
+
   @override
   Future<void> putAll(Map<dynamic, dynamic> kvPairs) async {
     checkOpen();

hive/lib/src/isolate/isolated_box.dart

@@ -77,8 +77,26 @@ abstract class IsolatedBoxBase<E> {
   /// Get a value from the box
   Future<E?> get(dynamic key, {E? defaultValue});
 
+  /// Get a value from the box and cast the value to [List<T>]
+  Future<List<T>?> getList<T>(dynamic key, {List<T>? defaultValue});
+
+  /// Get a value from the box and cast the value to [Set<T>]
+  Future<Set<T>?> getSet<T>(dynamic key, {Set<T>? defaultValue});
+
+  /// Get a value from the box and cast the value to [Map<K, V>]
+  Future<Map<K, V>?> getMap<K, V>(dynamic key, {Map<K, V>? defaultValue});
+
   /// Get a value at the given index
   Future<E?> getAt(int index);
+
+  /// Get a value at the given index and cast the value to [List<T>]
+  Future<List<T>?> getListAt<T>(int index, {List<T>? defaultValue});
+
+  /// Get a value at the given index and cast the value to [Set<T>]
+  Future<Set<T>?> getSetAt<T>(int index, {Set<T>? defaultValue});
+
+  /// Get a value at the given index and cast the value to [Map<K, V>]
+  Future<Map<K, V>?> getMapAt<K, V>(int index, {Map<K, V>? defaultValue});
 }
 
 /// Isolated version of [Box]

hive/lib/src/isolate/isolated_box_impl/isolated_box_impl_vm.dart

@@ -5,6 +5,7 @@ import 'package:hive_ce/hive.dart';
 import 'package:hive_ce/src/binary/binary_reader_impl.dart';
 import 'package:hive_ce/src/binary/binary_writer_impl.dart';
 import 'package:hive_ce/src/isolate/isolated_hive_impl/impl/isolated_hive_impl_vm.dart';
+import 'package:hive_ce/src/util/type_utils.dart';
 import 'package:isolate_channel/isolate_channel.dart';
 
 /// Isolated implementation of [BoxBase]
@@ -154,13 +155,43 @@ abstract class IsolatedBoxBaseImpl<E> implements IsolatedBoxBase<E> {
     return _readValue(result);
   }
 
+  @override
+  Future<List<T>?> getList<T>(dynamic key, {List<T>? defaultValue}) async =>
+      castList(await get(key), defaultValue: defaultValue);
+
+  @override
+  Future<Set<T>?> getSet<T>(dynamic key, {Set<T>? defaultValue}) async =>
+      castSet(await get(key), defaultValue: defaultValue);
+
+  @override
+  Future<Map<K, V>?> getMap<K, V>(
+    dynamic key, {
+    Map<K, V>? defaultValue,
+  }) async =>
+      castMap(await get(key), defaultValue: defaultValue);
+
   @override
   Future<E?> getAt(int index) async {
     final bytes =
         await _channel.invokeMethod('getAt', {'name': name, 'index': index});
     return _readValue(bytes);
   }
 
+  @override
+  Future<List<T>?> getListAt<T>(int index, {List<T>? defaultValue}) async =>
+      castList(await getAt(index), defaultValue: defaultValue);
+
+  @override
+  Future<Set<T>?> getSetAt<T>(int index, {Set<T>? defaultValue}) async =>
+      castSet(await getAt(index), defaultValue: defaultValue);
+
+  @override
+  Future<Map<K, V>?> getMapAt<K, V>(
+    int index, {
+    Map<K, V>? defaultValue,
+  }) async =>
+      castMap(await getAt(index), defaultValue: defaultValue);
+
   Uint8List _writeValue(E value) {
     final writer = BinaryWriterImpl(_hive);
     if (_cipher != null) {

hive/lib/src/isolate/isolated_box_impl/isolated_box_impl_web.dart

@@ -1,6 +1,7 @@
 import 'dart:async';
 
 import 'package:hive_ce/hive.dart';
+import 'package:hive_ce/src/util/type_utils.dart';
 import 'package:meta/meta.dart';
 
 /// Web implementation of [IsolatedBoxBase]
@@ -93,6 +94,21 @@ abstract class IsolatedBoxBaseImpl<E> implements IsolatedBoxBase<E> {
     }
   }
 
+  @override
+  Future<List<T>?> getList<T>(dynamic key, {List<T>? defaultValue}) async =>
+      castList(await get(key), defaultValue: defaultValue);
+
+  @override
+  Future<Set<T>?> getSet<T>(dynamic key, {Set<T>? defaultValue}) async =>
+      castSet(await get(key), defaultValue: defaultValue);
+
+  @override
+  Future<Map<K, V>?> getMap<K, V>(
+    dynamic key, {
+    Map<K, V>? defaultValue,
+  }) async =>
+      castMap(await get(key), defaultValue: defaultValue);
+
   @override
   Future<E?> getAt(int index) async {
     if (lazy) {
@@ -102,6 +118,21 @@ abstract class IsolatedBoxBaseImpl<E> implements IsolatedBoxBase<E> {
     }
   }
 
+  @override
+  Future<List<T>?> getListAt<T>(int index, {List<T>? defaultValue}) async =>
+      castList(await getAt(index), defaultValue: defaultValue);
+
+  @override
+  Future<Set<T>?> getSetAt<T>(int index, {Set<T>? defaultValue}) async =>
+      castSet(await getAt(index), defaultValue: defaultValue);
+
+  @override
+  Future<Map<K, V>?> getMapAt<K, V>(
+    int index, {
+    Map<K, V>? defaultValue,
+  }) async =>
+      castMap(await getAt(index), defaultValue: defaultValue);
+
   @override
   bool operator ==(Object other) {
     return other is IsolatedBoxBaseImpl && other._box == _box;

hive/lib/src/util/type_utils.dart

@@ -15,12 +15,40 @@ void typedMapOrIterableCheck<E>() {
   final type = E.toString();
   if (type.startsWith('Map<') && type != 'Map<dynamic, dynamic>') {
     throw AssertionError(
-      'Cannot open a box of type $type. It is not possible to read typed Maps. Use Map.cast<RK, RV>() after reading.',
+      'Cannot open a box of type $type. Instead open a `Box<Map>` and call `getMap<K, V>()`.',
     );
   } else if ({'Iterable<', 'List<', 'Set<'}.any(type.startsWith) &&
       !_allowedIterableTypes.any(type.endsWith)) {
+    final iterableType = type.substring(0, type.indexOf('<'));
     throw AssertionError(
-      'Cannot open a box of type $type. It is not possible to read Iterables of custom types. Use Iterable.cast<R>() after reading.',
+      'Cannot open a box of type $type. Instead open a `Box<$iterableType>` and call `get$iterableType<T>()`.',
     );
   }
 }
+
+/// Common logic for casting a typed list
+List<T>? castList<T>(Object? value, {List<T>? defaultValue}) {
+  if (value != null) {
+    return (value as List).cast<T>();
+  } else {
+    return defaultValue;
+  }
+}
+
+/// Common logic for casting a typed set
+Set<T>? castSet<T>(Object? value, {Set<T>? defaultValue}) {
+  if (value != null) {
+    return (value as Set).cast<T>();
+  } else {
+    return defaultValue;
+  }
+}
+
+/// Common logic for casting a typed map
+Map<K, V>? castMap<K, V>(Object? value, {Map<K, V>? defaultValue}) {
+  if (value != null) {
+    return (value as Map).cast<K, V>();
+  } else {
+    return defaultValue;
+  }
+}

hive/test/tests/box/box_impl_test.dart

@@ -94,6 +94,62 @@ void main() {
       expect(box.getAt(1), 'A');
     });
 
+    group('Iterable and Map casting', () {
+      test('.getList()', () {
+        final keystore = Keystore.debug(frames: [
+          Frame(0, [1, 2, 3]),
+        ]);
+        final box = _getBox(keystore: keystore);
+
+        expect(box.getList<num>(0), [1, 2, 3]);
+      });
+
+      test('.getSet()', () {
+        final keystore = Keystore.debug(frames: [
+          Frame(0, {1, 2, 3}),
+        ]);
+        final box = _getBox(keystore: keystore);
+
+        expect(box.getSet<num>(0), {1, 2, 3});
+      });
+
+      test('.getMap()', () {
+        final keystore = Keystore.debug(frames: [
+          Frame(0, {'a': 1, 'b': 2, 'c': 3}),
+        ]);
+        final box = _getBox(keystore: keystore);
+
+        expect(box.getMap<String, num>(0), {'a': 1, 'b': 2, 'c': 3});
+      });
+
+      test('.getListAt()', () {
+        final keystore = Keystore.debug(frames: [
+          Frame(0, [1, 2, 3]),
+        ]);
+        final box = _getBox(keystore: keystore);
+
+        expect(box.getListAt<num>(0), [1, 2, 3]);
+      });
+
+      test('.getSetAt()', () {
+        final keystore = Keystore.debug(frames: [
+          Frame(0, {1, 2, 3}),
+        ]);
+        final box = _getBox(keystore: keystore);
+
+        expect(box.getSetAt<num>(0), {1, 2, 3});
+      });
+
+      test('.getMapAt()', () {
+        final keystore = Keystore.debug(frames: [
+          Frame(0, {'a': 1, 'b': 2, 'c': 3}),
+        ]);
+        final box = _getBox(keystore: keystore);
+
+        expect(box.getMapAt<String, num>(0), {'a': 1, 'b': 2, 'c': 3});
+      });
+    });
+
     group('.putAll()', () {
       test('values', () async {
         final frames = <Frame>[