Drop final requirement on primary keys for now

CHANGELOG.md

@@ -1,3 +1,10 @@
+vNext
+==============================================================
+
+### Changes
+* Primary key annotation no longer requires field to be final.
+
+
 0.2.0+alpha Release notes (2022-01-31)
 ==============================================================
 

README.md

@@ -121,7 +121,7 @@ The Realm Flutter package name is `realm`
     @RealmModel()
     class _Item {
         @PrimaryKey()
-        late final int id;
+        late int id;
 
         late String name;
 

generator/lib/src/field_element_ex.dart

@@ -105,6 +105,19 @@ extension FieldElementEx on FieldElement {
             element: this,
           ));
         }
+        // Since the setter of a dart late final public field without initializer is public,
+        // the error of setting a primary key after construction will be a runtime error no matter 
+        // what we do. See: 
+        //
+        //  https://github.com/dart-lang/language/issues/1239
+        //  https://github.com/dart-lang/language/issues/2068
+        //
+        // Hence we may as well lift the restriction that primary keys must be declared final.
+        //
+        // However, this may change in the future. Either as the dart language team change this
+        // blemish. Or perhaps we can avoid the late modifier, once static meta programming lands 
+        // in dart. Therefor we keep the code outcommented for later.
+        /*
         if (!isFinal) {
           throw RealmInvalidGenerationSourceError(
             'Primary key field is not final',
@@ -116,6 +129,7 @@ extension FieldElementEx on FieldElement {
             element: this,
           );
         }
+        */
       }
 
       // Validate indexes

generator/test/generator_test.dart

@@ -226,46 +226,6 @@ class _Bad {
     );
   });
 
-  test('primary key not final', () async {
-    await expectLater(
-      () async => await testBuilder(
-        generateRealmObjects(),
-        {
-          'pkg|lib/src/test.dart': r'''
-import 'package:realm_common/realm_common.dart';
-
-part 'test.g.dart';
-
-@RealmModel()
-class _Bad {
-  @PrimaryKey()
-  late int primaryKeyIsNotFinal;
-}'''
-        },
-        reader: await PackageAssetReader.currentIsolate(),
-      ),
-      throwsA(
-        isA<RealmInvalidGenerationSourceError>().having(
-          (e) => e.format(),
-          'format()',
-          'Primary key field is not final\n'
-              '\n'
-              'in: package:pkg/src/test.dart:8:12\n'
-              '  ╷\n'
-              '5 │ @RealmModel()\n'
-              '6 │ class _Bad {\n'
-              '  │       ━━━━ in realm model for \'Bad\'\n'
-              '7 │   @PrimaryKey()\n'
-              '8 │   late int primaryKeyIsNotFinal;\n'
-              '  │            ^^^^^^^^^^^^^^^^^^^^ is not final\n'
-              '  ╵\n'
-              'Add a final keyword to the definition of \'primaryKeyIsNotFinal\', or remove the @PrimaryKey annotation.\n'
-              '',
-        ),
-      ),
-    );
-  });
-
   test('primary keys always indexed', () async {
     final sb = StringBuffer();
     var done = false;