Ignore Attribute in Mapping

example/lib/ignore/ignore.dart

@@ -0,0 +1,22 @@
+import 'package:smartstruct/smartstruct.dart';
+part 'ignore.mapper.g.dart';
+
+class IgnoreSource {
+  final String ignoreMe;
+  final String doNotIgnoreMe;
+
+  IgnoreSource(this.ignoreMe, this.doNotIgnoreMe);
+}
+
+class IgnoreTarget {
+  String? ignoreMe;
+  final String doNotIgnoreMe;
+
+  IgnoreTarget(this.doNotIgnoreMe);
+}
+
+@Mapper()
+abstract class IgnoreMapper {
+  @Mapping(target: 'ignoreMe', ignore: true)
+  IgnoreTarget fromIgnore(IgnoreSource source);
+}

generator/lib/code_builders/method_builder.dart

@@ -1,6 +1,5 @@
 import 'dart:collection';
 
-import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:code_builder/code_builder.dart';
 import 'package:smartstruct_generator/code_builders/parameter_copy.dart';
@@ -175,19 +174,26 @@ List<HashMap<String, SourceAssignment>> _targetToSource(
 
   /// If there are Mapping Annotations on the method, the source attribute of the source mapping class,
   /// will be replaced with the source attribute of the given mapping config.
-  mappingConfig.forEach((sourceField, targetField) {
-    if (sourceField.toFunctionValue() != null) {
-      targetToSource[targetField] = SourceAssignment.fromFunction(
-          sourceField.toFunctionValue()!, [...sources]);
-    }
-    if (sourceField.toStringValue() != null) {
-      final sourceFieldString = sourceField.toStringValue()!;
-      if (targetToSource.containsKey(sourceFieldString)) {
-        targetToSource.putIfAbsent(
-            targetField, () => targetToSource[sourceFieldString]!);
-        targetToSource.remove(sourceFieldString);
+  mappingConfig.forEach((targetField, mappingConfig) {
+    final sourceField = mappingConfig.source;
+    if (sourceField != null) {
+      if (sourceField.toFunctionValue() != null) {
+        targetToSource[targetField] = SourceAssignment.fromFunction(
+            sourceField.toFunctionValue()!, [...sources]);
+      } else if (sourceField.toStringValue() != null) {
+        final sourceFieldString = sourceField.toStringValue()!;
+        if (targetToSource.containsKey(sourceFieldString)) {
+          targetToSource.putIfAbsent(
+              targetField, () => targetToSource[sourceFieldString]!);
+
+          targetToSource.remove(sourceFieldString);
+        }
       }
     }
+
+    if (mappingConfig.ignore) {
+      targetToSource.remove(targetField);
+    }
   });
 
   return [targetToSource, customTargetToSource];

generator/lib/generators/mapper_generator.dart

@@ -23,8 +23,14 @@ class MapperGenerator extends GeneratorForAnnotation<Mapper> {
 
     var config = MapperConfig.readMapperConfig(annotation, element);
 
-    final mapperImpl = buildMapperClass(element, config);
-    final emitter = DartEmitter();
-    return '${mapperImpl.accept(emitter)}';
+    try {
+      final mapperImpl = buildMapperClass(element, config);
+      final emitter = DartEmitter();
+      return '${mapperImpl.accept(emitter)}';
+    } on Error catch (e) {
+      print(e);
+      print(e.stackTrace);
+      rethrow;
+    }
   }
 }

generator/lib/mapper_config.dart

@@ -12,24 +12,34 @@ class MapperConfig {
     var mapper =
         mappingClass.metadata[0].element!.enclosingElement as ClassElement;
     final config = <String, dynamic>{};
-    mapper.fields.forEach((field) {
+
+    for (final field in mapper.fields) {
       final configField = annotation.read(field.name).literalValue;
       config.putIfAbsent(field.name, () => configField);
-    });
+    }
     return config;
   }
 
   /// Reads the attributes of the [Mapping] annotations of a given Method,
-  /// and returns key value pairs, where the key is the source, and the value is the target attribute of the read Mapping
-  static Map<DartObject, String> readMappingConfig(MethodElement method) {
-    final config = <DartObject, String>{};
+  /// and returns key value pairs, where the key is the target, and the value is an instance of [MappingConfig] containing the source and other meta attributes
+  static Map<String, MappingConfig> readMappingConfig(MethodElement method) {
+    final config = <String, MappingConfig>{};
     final annotations = TypeChecker.fromRuntime(Mapping).annotationsOf(method);
 
-    annotations.forEach((element) {
-      var reader = ConstantReader(element);
-      config[reader.read('source').objectValue] =
-          reader.read('target').stringValue;
-    });
+    for (final element in annotations) {
+      final reader = ConstantReader(element);
+      final sourceReader = reader.read('source');
+      config[reader.read('target').stringValue] = MappingConfig(
+          sourceReader.isNull ? null : sourceReader.objectValue,
+          reader.read('ignore').boolValue);
+    }
     return config;
   }
 }
+
+class MappingConfig {
+  final DartObject? source;
+  final bool ignore;
+
+  MappingConfig(this.source, this.ignore);
+}

generator/test/mapper_test.dart

@@ -30,5 +30,6 @@ const _expectedAnnotatedTests = {
   'ConstructorMapper',
   'FunctionFieldMapper',
   'InheritanceMapper',
-  'MultipleSourceMapper'
+  'MultipleSourceMapper',
+  'IgnoreMapper'
 };

generator/test/src/ignore_field_mapper_input.dart

@@ -0,0 +1,32 @@
+part of 'mapper_test_input.dart';
+
+class IgnoreSource {
+  final String ignoreMe;
+  final String doNotIgnoreMe;
+
+  IgnoreSource(this.ignoreMe, this.doNotIgnoreMe);
+}
+
+class IgnoreTarget {
+  String? ignoreMe;
+  final String doNotIgnoreMe;
+
+  IgnoreTarget(this.doNotIgnoreMe);
+}
+
+@Mapper()
+@ShouldGenerate(r'''
+class IgnoreMapperImpl extends IgnoreMapper {
+  IgnoreMapperImpl() : super();
+
+  @override
+  IgnoreTarget fromIgnore(IgnoreSource source) {
+    final ignoretarget = IgnoreTarget(source.doNotIgnoreMe);
+    return ignoretarget;
+  }
+}
+''')
+abstract class IgnoreMapper {
+  @Mapping(target: 'ignoreMe', ignore: true)
+  IgnoreTarget fromIgnore(IgnoreSource source);
+}

generator/test/src/mapper_test_input.dart

@@ -10,6 +10,7 @@ part 'constructor_mapper_input.dart';
 part 'function_mapper_input.dart';
 part 'inheritance_mapper_input.dart';
 part 'multiple_source_mapper_input.dart';
+part 'ignore_field_mapper_input.dart';
 
 @ShouldThrow('theAnswer is not a class and cannot be annotated with @Mapper')
 @Mapper()

smartstruct/lib/src/annotations.dart

@@ -16,5 +16,6 @@ const mapper = Mapper();
 class Mapping {
   final dynamic source;
   final String target;
-  const Mapping({required this.source, required this.target});
+  final bool ignore;
+  const Mapping({required this.target, this.source, this.ignore = false});
 }