Generator: find backlink source also if target is processed first #125

Author: greenrobot-team

generator/lib/src/code_builder.dart

@@ -369,7 +369,10 @@ class CodeBuilder extends Builder {
         }
         rel.targetId = targetEntity.id;
       }
-
+    }
+    // Note: finding the backlink source requires that all ToMany relations have
+    // a targetId set, so find backlink sources in a separate loop.
+    for (var entity in model.entities) {
       for (var backlink in entity.backlinks) {
         backlink.source = _findBacklinkSource(model, entity, backlink);
       }

generator/test/code_builder_test.dart

@@ -271,6 +271,59 @@ void main() {
       ''');
     });
 
+    test('Finds backlink source if type is unique', () async {
+      final source = r'''
+      library example;     
+      import 'package:objectbox/objectbox.dart';
+      
+      @Entity()
+      class Example {
+        @Id()
+        int id = 0;
+        
+        final relA = ToMany<A>();
+        final relB = ToOne<B>();
+      }
+      
+      // Name related classes to be lexically before Example so they are
+      // processed first.
+       
+      @Entity()
+      class A {
+        @Id()
+        int id = 0;
+        
+        @Backlink()
+        final backRel = ToMany<Example>();
+      }
+      
+      @Entity()
+      class B {
+        @Id()
+        int id = 0;
+        
+        @Backlink()
+        final backRel = ToMany<Example>();
+      }
+      ''';
+
+      final testEnv = GeneratorTestEnv();
+      await testEnv.run(source);
+
+      final entityA = testEnv.model.entities.firstWhere((e) => e.name == 'A');
+      var backlinkSourceA = entityA.backlinks.first.source;
+      expect(backlinkSourceA, isA<BacklinkSourceRelation>());
+      expect((backlinkSourceA as BacklinkSourceRelation).srcRel.name, 'relA');
+
+      final entityB = testEnv.model.entities.firstWhere((e) => e.name == 'B');
+      var backlinkSourceB = entityB.backlinks.first.source;
+      expect(backlinkSourceB, isA<BacklinkSourceProperty>());
+      expect(
+        (backlinkSourceB as BacklinkSourceProperty).srcProp.relationField,
+        'relB',
+      );
+    });
+
     test('@TargetIdProperty ToOne annotation', () async {
       final source = r'''
       library example;     

objectbox/CHANGELOG.md

@@ -15,6 +15,8 @@
   MongoDB to match the name used in the MongoDB database. [#713](https://github.com/objectbox/objectbox-dart/issues/713)
 * Provide a helpful error message if the name of a property conflicts with a target ID property 
   created for a `ToOne` relation. [#713](https://github.com/objectbox/objectbox-dart/issues/713)
+* Generator: find `@Backlink()` source relation also in case target entity class is processed first.
+  [#687](https://github.com/objectbox/objectbox-dart/issues/687)
 
 ### Sync