feat: add HiveConverter for custom TypeAdapter field conversion

hive/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 2.20.0
+
+- Adds `HiveConverter` for custom field conversion during TypeAdapter generation (similar to `json_serializable`'s `JsonConverter`)
+- Adds `converters` parameter to `GenerateAdapters`
+
 ## 2.19.3
 
 - IsolatedHive: Handles stale send ports on hot restart

hive/lib/hive.dart

@@ -11,6 +11,7 @@ export 'src/box_collection/box_collection_stub.dart'
 export 'src/object/hive_object.dart' show HiveObject, HiveObjectMixin;
 
 export 'src/annotations/generate_adapters.dart';
+export 'src/annotations/hive_converter.dart';
 export 'src/annotations/hive_field.dart';
 export 'src/annotations/hive_type.dart';
 export 'src/binary/binary_reader.dart';

hive/lib/src/annotations/generate_adapters.dart

@@ -1,3 +1,4 @@
+import 'package:hive_ce/src/annotations/hive_converter.dart';
 import 'package:meta/meta.dart';
 
 /// Annotation to generate TypeAdapters for the given [specs]
@@ -9,6 +10,7 @@ class GenerateAdapters {
     this.specs, {
     this.firstTypeId = 0,
     this.reservedTypeIds = const {},
+    this.converters = const [],
   });
   // coverage:ignore-end
 
@@ -22,6 +24,12 @@ class GenerateAdapters {
   ///
   /// These type ids will be skipped during generation
   final Set<int> reservedTypeIds;
+
+  /// A list of [HiveConverter]s to apply when generating adapters for [specs]
+  ///
+  /// A converter is selected by matching its type parameter [T] against each
+  /// field type. See [HiveConverter] for details.
+  final List<HiveConverter> converters;
 }
 
 /// Configuration that specifies the generation of a TypeAdapter

hive/lib/src/annotations/hive_converter.dart

@@ -0,0 +1,42 @@
+import 'package:meta/meta.dart';
+
+/// Implement this class to provide custom converters for a specific [Type].
+///
+/// [T] is the data type you'd like to convert to and from.
+///
+/// [S] is the type of the value stored in Hive. It must be a type Hive can
+/// write natively (such as [String], [int], [List], [Set], or [Map]) or a type
+/// with a registered [TypeAdapter].
+///
+/// Pass converter instances to [GenerateAdapters.converters]:
+///
+/// ```dart
+/// class UriConverter implements HiveConverter<Uri, String> {
+///   const UriConverter();
+///
+///   @override
+///   Uri fromHive(String hive) => Uri.parse(hive);
+///
+///   @override
+///   String toHive(Uri object) => object.toString();
+/// }
+///
+/// @GenerateAdapters(
+///   [AdapterSpec<Website>()],
+///   converters: [UriConverter()],
+/// )
+/// class Website {
+///   final Uri url;
+/// }
+/// ```
+@immutable
+abstract class HiveConverter<T, S> {
+  /// Constructor
+  const HiveConverter();
+
+  /// Convert a value read from Hive into [T].
+  T fromHive(S hive);
+
+  /// Convert a [T] value into a value Hive can write.
+  S toHive(T object);
+}

hive/pubspec.yaml

@@ -1,6 +1,6 @@
 name: hive_ce
 description: Hive Community Edition - A spiritual continuation of Hive v2
-version: 2.19.3
+version: 2.20.0
 homepage: https://github.com/IO-Design-Team/hive_ce/tree/main/hive
 
 topics:

hive_generator/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 1.12.0
+
+- Adds support for `HiveConverter` via `GenerateAdapters.converters` (similar to `json_serializable`'s `JsonConverter`)
+- Supports generic converters with inferred type arguments (e.g. `WrappedListConverter<String>`)
+
 ## 1.11.3
 
 - Upgrades `analyzer` to `14.0.0`

hive_generator/example/lib/hive/hive_adapters.dart

@@ -1,15 +1,31 @@
 import 'package:hive_ce/hive_ce.dart';
 import 'package:meta/meta.dart';
 
-@GenerateAdapters([
-  AdapterSpec<ClassSpec1>(),
-  AdapterSpec<ClassSpec2>(),
-  AdapterSpec<ClassSpec3>(),
-  AdapterSpec<ClassSpec4>(),
-  AdapterSpec<EnumSpec>(),
-], firstTypeId: 50)
+@GenerateAdapters(
+  [
+    AdapterSpec<ClassSpec1>(),
+    AdapterSpec<ClassSpec2>(),
+    AdapterSpec<ClassSpec3>(),
+    AdapterSpec<ClassSpec4>(),
+    AdapterSpec<EnumSpec>(),
+    AdapterSpec<ClassSpec5>(),
+  ],
+  firstTypeId: 50,
+  converters: [UriConverter()],
+)
 part 'hive_adapters.g.dart';
 
+/// Example converter matching json_serializable's JsonConverter pattern
+class UriConverter implements HiveConverter<Uri, String> {
+  const UriConverter();
+
+  @override
+  Uri fromHive(String hive) => Uri.parse(hive);
+
+  @override
+  String toHive(Uri object) => object.toString();
+}
+
 @immutable
 class ClassSpec1 {
   final int value;
@@ -41,3 +57,11 @@ enum EnumSpec {
 
   EnumSpec get getter => EnumSpec.value2;
 }
+
+@immutable
+class ClassSpec5 {
+  final Uri url;
+  final Uri? optionalUrl;
+
+  const ClassSpec5(this.url, this.optionalUrl);
+}

hive_generator/example/lib/hive/hive_adapters.g.yaml

@@ -1,7 +1,7 @@
 # Generated by Hive CE
 # Manual modifications may be necessary for certain migrations
 # Check in to version control
-nextTypeId: 55
+nextTypeId: 56
 types:
   ClassSpec1:
     typeId: 50
@@ -39,6 +39,14 @@ types:
     fields:
       value:
         index: 0
+  ClassSpec5:
+    typeId: 55
+    nextIndex: 2
+    fields:
+      url:
+        index: 0
+      optionalUrl:
+        index: 1
   ClassSpec4:
     typeId: 54
     nextIndex: 0

hive_generator/example/lib/hive/hive_registrar.g.dart

@@ -16,6 +16,7 @@ extension HiveRegistrar on HiveInterface {
     registerAdapter(ClassSpec2Adapter());
     registerAdapter(ClassSpec3Adapter());
     registerAdapter(ClassSpec4Adapter());
+    registerAdapter(ClassSpec5Adapter());
     registerAdapter(ConstructorDefaultsAdapter());
     registerAdapter(EmptyClassAdapter());
     registerAdapter(Enum1Adapter());
@@ -34,6 +35,7 @@ extension IsolatedHiveRegistrar on IsolatedHiveInterface {
     registerAdapter(ClassSpec2Adapter());
     registerAdapter(ClassSpec3Adapter());
     registerAdapter(ClassSpec4Adapter());
+    registerAdapter(ClassSpec5Adapter());
     registerAdapter(ConstructorDefaultsAdapter());
     registerAdapter(EmptyClassAdapter());
     registerAdapter(Enum1Adapter());

hive_generator/lib/src/adapter_builder/adapter_builder.dart

@@ -49,12 +49,16 @@ abstract class AdapterBuilder {
   /// TODO: Document this!
   final List<AdapterField> setters;
 
+  /// Converters from [GenerateAdapters.converters]
+  final List<DartObject> converters;
+
   /// TODO: Document this!
   const AdapterBuilder(
     this.cls,
-    this.getters, [
+    this.getters, {
     this.setters = const <AdapterField>[],
-  ]);
+    this.converters = const [],
+  });
 
   /// TODO: Document this!
   String buildRead();

hive_generator/lib/src/adapter_builder/class_adapter_builder.dart

@@ -12,16 +12,18 @@ import 'package:hive_ce_generator/src/adapter_builder/adapter_builder.dart';
 import 'package:hive_ce_generator/src/helper/helper.dart';
 import 'package:source_gen/source_gen.dart';
 
+import 'package:hive_ce_generator/src/helper/hive_converter_helper.dart';
 import 'package:hive_ce_generator/src/helper/type_helper.dart';
 
 /// TODO: Document this!
 class ClassAdapterBuilder extends AdapterBuilder {
   /// TODO: Document this!
   const ClassAdapterBuilder(
     super.cls,
-    super.getters,
+    super.getters, {
     super.setters,
-  );
+    super.converters,
+  });
 
   /// [TypeChecker] for [HiveList].
   final hiveListChecker =
@@ -121,6 +123,13 @@ class ClassAdapterBuilder extends AdapterBuilder {
   }
 
   String _cast(DartType type, String variable) {
+    final converter = _converterFor(type);
+    if (converter != null) {
+      final call =
+          '${converter.access}.fromHive($variable as ${converter.hiveType})';
+      return _nullSafe(type, variable, call);
+    }
+
     final suffix = _suffixFromType(type);
     if (hiveListChecker.isAssignableFromType(type)) {
       return '($variable as HiveList$suffix)$suffix.castHiveList()';
@@ -155,7 +164,8 @@ class ClassAdapterBuilder extends AdapterBuilder {
     final paramType = type as ParameterizedType;
     final arg = paramType.typeArguments.first;
     final suffix = _accessorSuffixFromType(type);
-    if (isMapOrIterable(arg) && !isUint8List(arg)) {
+    if (isMapOrIterable(arg) && !isUint8List(arg) ||
+        _converterFor(arg) != null) {
       var cast = '';
       // Using assignable because Set? is not exactly Set
       if (setChecker.isAssignableFromType(type)) {
@@ -176,7 +186,10 @@ class ClassAdapterBuilder extends AdapterBuilder {
     final arg1 = paramType.typeArguments[0];
     final arg2 = paramType.typeArguments[1];
     final suffix = _accessorSuffixFromType(type);
-    if (isMapOrIterable(arg1) || isMapOrIterable(arg2)) {
+    if (isMapOrIterable(arg1) ||
+        isMapOrIterable(arg2) ||
+        _converterFor(arg1) != null ||
+        _converterFor(arg2) != null) {
       return '$suffix.map((dynamic k, dynamic v)=>'
           'MapEntry(${_cast(arg1, 'k')},${_cast(arg2, 'v')}))';
     } else {
@@ -195,12 +208,58 @@ class ClassAdapterBuilder extends AdapterBuilder {
     for (final field in getters) {
       code.writeln('''
       ..writeByte(${field.index})
-      ..write(obj.${field.name})''');
+      ..write(${_writeValue(field.type, 'obj.${field.name}')})''');
     }
     code.writeln(';');
 
     return code.toString();
   }
+
+  String _writeValue(DartType type, String expression) {
+    final converter = _converterFor(type);
+    if (converter != null) {
+      final nullable = type.nullabilitySuffix == NullabilitySuffix.question;
+      final value =
+          nullable ? '$expression as ${converter.fieldType}' : expression;
+      return _nullSafe(
+        type,
+        expression,
+        '${converter.access}.toHive($value)',
+      );
+    }
+
+    if (setChecker.isAssignableFromType(type) ||
+        (iterableChecker.isAssignableFromType(type) && !isUint8List(type))) {
+      final arg = (type as ParameterizedType).typeArguments.first;
+      final inner = _writeValue(arg, 'e');
+      if (inner == 'e') return expression;
+      final suffix = _accessorSuffixFromType(type);
+      final mapped = '$expression$suffix.map((e) => $inner)';
+      return setChecker.isAssignableFromType(type)
+          ? '$mapped.toSet()'
+          : '$mapped.toList()';
+    }
+
+    if (mapChecker.isAssignableFromType(type)) {
+      final args = (type as ParameterizedType).typeArguments;
+      final key = _writeValue(args[0], 'k');
+      final value = _writeValue(args[1], 'v');
+      if (key == 'k' && value == 'v') return expression;
+      final suffix = _accessorSuffixFromType(type);
+      return '$expression$suffix.map((dynamic k, dynamic v) => '
+          'MapEntry($key, $value))';
+    }
+
+    return expression;
+  }
+
+  String _nullSafe(DartType type, String expression, String call) {
+    if (type.nullabilitySuffix != NullabilitySuffix.question) return call;
+    return '$expression == null ? null : $call';
+  }
+
+  HiveConverterMatch? _converterFor(DartType type) =>
+      findHiveConverter(type, converters);
 }
 
 /// Suffix to use when accessing a field in [type].

hive_generator/lib/src/generator/adapters_generator.dart

@@ -96,6 +96,7 @@ class AdaptersGenerator extends GeneratorForAnnotation<GenerateAdapters> {
         typeId: schemaType.typeId,
         schema: schemaType,
         ignoredFields: spec.ignoredFields,
+        converters: revived.converters,
       );
 
       content.write(result.content);