fix: #3142 Cascading a OneToMany, set the relationship when the child isn't new or dirty

ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanPropertyAssocMany.java

@@ -588,10 +588,9 @@ public TableJoin intersectionTableJoin() {
   }
 
   /**
-   * Set the join properties from the parent bean to the child bean.
-   * This is only valid for OneToMany and NOT valid for ManyToMany.
+   * Set the parent bean to the child (update the relationship).
    */
-  public void setJoinValuesToChild(EntityBean parent, EntityBean child, Object mapKeyValue) {
+  public void setParentToChild(EntityBean parent, EntityBean child, Object mapKeyValue) {
     if (mapKeyProperty != null) {
       mapKeyProperty.setValue(child, mapKeyValue);
     }
@@ -602,6 +601,31 @@ public void setJoinValuesToChild(EntityBean parent, EntityBean child, Object map
     }
   }
 
+  /**
+   * Return true if the parent bean has been set to the child (updated the relationship).
+   */
+  public boolean setParentToChild(EntityBean parent, EntityBean child, Object mapKeyValue, BeanDescriptor<?> parentDesc) {
+    if (manyToMany
+      || childMasterProperty == null
+      || !child._ebean_getIntercept().isLoadedProperty(childMasterProperty.propertyIndex())) {
+      return false;
+    }
+
+    Object currentParent = childMasterProperty.getValue(child);
+    if (currentParent != null) {
+      Object newId = parentDesc.getId(parent);
+      Object oldId = parentDesc.id(currentParent);
+      if (Objects.equals(newId, oldId)) {
+        return false;
+      }
+    }
+    childMasterProperty.setValueIntercept(child, parent);
+    if (mapKeyProperty != null) {
+      mapKeyProperty.setValue(child, mapKeyValue);
+    }
+    return true;
+  }
+
   /**
    * Return the order by clause used to order the fetching of the data for
    * this list, set or map.

ebean-core/src/main/java/io/ebeaninternal/server/persist/SaveManyBeans.java

@@ -172,7 +172,9 @@ private void saveAllBeans(final BeanProperty orderColumn) {
           } else if (ebi.isNewOrDirty()) {
             skipSavingThisBean = false;
             // set the parent bean to detailBean
-            many.setJoinValuesToChild(parentBean, detail, mapKeyValue);
+            many.setParentToChild(parentBean, detail, mapKeyValue);
+          } else if (many.setParentToChild(parentBean, detail, mapKeyValue, request.descriptor())) {
+            skipSavingThisBean = false;
           } else {
             skipSavingThisBean = saveRecurseSkippable;
           }

ebean-test/src/test/java/org/tests/saveassociation/TestSaveAssociation.java

@@ -6,12 +6,12 @@
 import org.tests.model.basic.TSDetail;
 import org.tests.model.basic.TSMaster;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.assertj.core.api.Assertions.assertThat;
 
-public class TestSaveAssociation extends BaseTestCase {
+class TestSaveAssociation extends BaseTestCase {
 
   @Test
-  public void test() {
+  void test() {
 
     TSMaster m0 = new TSMaster();
     m0.setName("master1");
@@ -26,7 +26,57 @@ public void test() {
     TSMaster m0Check = DB.find(TSMaster.class).fetch("details").where().idEq(m0.getId())
       .findOne();
 
-    assertEquals(2, m0Check.getDetails().size());
+    assertThat(m0Check.getDetails()).hasSize(2);
+    DB.delete(m0);
   }
 
+
+  @Test
+  void testCascadeSetParent() {
+    // setup
+    TSDetail detail = new TSDetail("master1 detail1");
+    DB.save(detail);
+
+    // act
+    TSMaster m0 = new TSMaster();
+    m0.setName("master2");
+    m0.addDetail(detail);
+    DB.save(m0);
+
+    // assert
+    TSMaster check = DB.find(TSMaster.class).fetch("details")
+      .where().idEq(m0.getId())
+      .findOne();
+
+    assertThat(check.getDetails()).hasSize(1);
+    assertThat(check.getDetails().get(0).getId()).isEqualTo(detail.getId());
+    DB.delete(m0);
+  }
+
+  @Test
+  void testCascadeChangeParent() {
+    // setup
+    TSDetail detail = new TSDetail("master3 detail1");
+    TSMaster m0 = new TSMaster();
+    m0.setName("master3");
+    m0.addDetail(detail);
+    DB.save(m0);
+
+    // act
+    TSMaster m1 = new TSMaster();
+    m1.setName("master4");
+    m1.addDetail(detail);
+    DB.save(m1);
+
+    // assert
+    TSMaster check = DB.find(TSMaster.class).fetch("details")
+      .where().idEq(m1.getId())
+      .findOne();
+
+    assertThat(check.getDetails()).hasSize(1);
+    assertThat(check.getDetails().get(0).getId()).isEqualTo(detail.getId());
+
+    DB.delete(m1);
+    DB.delete(TSMaster.class, m0.getId());
+  }
 }