transient annotation is implemented

transient annotation is implemented to support the transient fields in entities

these fields should not be persisted to data tables in project's database and they only serve the data integrity

example/lib/task.dart

@@ -7,7 +7,10 @@ class Task {
 
   final String message;
 
-  Task(this.id, this.message);
+  @transient
+  String description;
+
+  Task(this.id, this.message, [this.description='']);
 
   @override
   bool operator ==(Object other) =>

floor_annotation/lib/floor_annotation.dart

@@ -12,4 +12,5 @@ export 'src/on_conflict_strategy.dart';
 export 'src/primary_key.dart';
 export 'src/query.dart';
 export 'src/transaction.dart';
+export 'src/transient.dart';
 export 'src/update.dart';

floor_annotation/lib/src/transient.dart

@@ -0,0 +1,7 @@
+/// Marks a field in an [Entity] as the transient.
+class Transient {
+  const Transient();
+}
+
+/// Marks a field in an [Entity] as the transient.
+const transient = Transient();

floor_generator/lib/processor/entity_processor.dart

@@ -30,16 +30,16 @@ class EntityProcessor extends Processor<Entity> {
   @override
   Entity process() {
     final name = _getName();
-    final fields = _getFields();
+    final allFieldsButTransients  = _getAllButTransientsFields();
 
     return Entity(
       _classElement,
       name,
-      fields,
-      _getPrimaryKey(fields),
+      allFieldsButTransients,
+      _getPrimaryKey(allFieldsButTransients),
       _getForeignKeys(),
-      _getIndices(fields, name),
-      _getConstructor(fields),
+      _getIndices(allFieldsButTransients, name),
+      _getConstructor(allFieldsButTransients),
     );
   }
 
@@ -53,9 +53,9 @@ class EntityProcessor extends Processor<Entity> {
   }
 
   @nonNull
-  List<Field> _getFields() {
+  List<Field> _getAllButTransientsFields() {
     return _classElement.fields
-        .where(_isNotHashCode)
+        .where(_isNotHashCode).where(_isNotTransient)
         .map((field) => FieldProcessor(field).process())
         .toList();
   }
@@ -65,6 +65,12 @@ class EntityProcessor extends Processor<Entity> {
     return fieldElement.displayName != 'hashCode';
   }
 
+  @nonNull
+  bool _isNotTransient(final FieldElement fieldElement) {
+    return !typeChecker(annotations.Transient)
+        .hasAnnotationOfExact(fieldElement);
+  }
+
   @nonNull
   List<ForeignKey> _getForeignKeys() {
     return _entityTypeChecker
@@ -231,7 +237,7 @@ class EntityProcessor extends Processor<Entity> {
   @nonNull
   String _getConstructor(final List<Field> fields) {
     final columnNames = fields.map((field) => field.columnName).toList();
-    final constructorParameters = _classElement.constructors.first.parameters;
+    final constructorParameters = _classElement.constructors.first.parameters. where((f)=> columnNames.contains(f.name)).toList();
 
     final parameterValues = <String>[];
 

floor_generator/lib/value_object/transient.dart

@@ -0,0 +1,21 @@
+import 'package:collection/collection.dart';
+import 'package:floor_generator/value_object/field.dart';
+
+/// Transient representation of a field in an Entity
+class Transient {
+  final List<Field> fields;
+
+  Transient(this.fields);
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is Transient &&
+          runtimeType == other.runtimeType &&
+          const ListEquality<Field>().equals(fields, other.fields);
+
+  @override
+  String toString() {
+    return 'Transient{fields: $fields}';
+  }
+}

floor_generator/test/processor/entity_processor_test.dart

@@ -128,6 +128,45 @@ void main() {
       expect(actual, equals(expected));
     });
   });
+
+  test('Should entity with transient field be not equals to floor processed entity', () async {
+     final classElement = await _createClassElement('''
+        @entity
+        class Person {
+        @primaryKey
+        final int id;
+
+        final String name;
+        
+        @transient
+        String nickName;
+
+        Person(this.id, this.name, [this.nickName='']);
+        }
+        ''');
+
+    final actual = EntityProcessor(classElement).process();
+
+    const name = 'Person';
+    final fields = classElement.fields
+        .map((fieldElement) => FieldProcessor(fieldElement).process())
+        .toList();
+    final primaryKey = PrimaryKey([fields[0]], false);
+    const foreignKeys = <ForeignKey>[];
+    const indices = <Index>[];
+    const constructor = "Person(row['id'] as int, row['name'] as String)";
+    final expected = Entity(
+      classElement,
+      name,
+      fields,
+      primaryKey,
+      foreignKeys,
+      indices,
+      constructor,
+    );
+
+    expect(actual.fields, isNot(equals(expected.fields)));
+  });
 }
 
 Future<ClassElement> _createClassElement(final String clazz) async {