From 2691221168c83dc155fb0cd401f7c58cef25576d Mon Sep 17 00:00:00 2001
From: rbygrave <robin.bygrave@gmail.com>
Date: Fri, 30 Jul 2021 22:53:51 +1200
Subject: [PATCH] #2278 - Do not override empty json collections, when database
 value is null

---
 .../ebeaninternal/server/deploy/BeanProperty.java   | 13 +++++++++++++
 .../server/deploy/BeanPropertyJsonMapper.java       |  3 +++
 .../test/java/org/tests/json/TestDbJson_List.java   |  3 +--
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanProperty.java b/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanProperty.java
index a33d183ea..d564a1f7a 100644
--- a/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanProperty.java
+++ b/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanProperty.java
@@ -50,6 +50,7 @@ import java.io.IOException;
 import java.lang.reflect.Field;
 import java.sql.SQLException;
 import java.sql.Types;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -623,9 +624,21 @@ public class BeanProperty implements ElPropertyValue, Property, STreeProperty {
     return scalarType.read(reader);
   }
 
+  protected Object checkForEmpty(EntityBean bean) {
+    final Object value = getValue(bean);
+    if (value instanceof Collection && ((Collection<?>) value).isEmpty()
+      || value instanceof Map && ((Map<?, ?>) value).isEmpty()) {
+      return value;
+    }
+    return null;
+  }
+
   public Object readSet(DataReader reader, EntityBean bean) throws SQLException {
     try {
       Object value = scalarType.read(reader);
+      if (value == null) {
+        value = checkForEmpty(bean);
+      }
       if (bean != null) {
         setValue(bean, value);
       }
diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanPropertyJsonMapper.java b/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanPropertyJsonMapper.java
index bc7392287..0b7cdebbc 100644
--- a/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanPropertyJsonMapper.java
+++ b/ebean-core/src/main/java/io/ebeaninternal/server/deploy/BeanPropertyJsonMapper.java
@@ -76,6 +76,9 @@ public class BeanPropertyJsonMapper extends BeanProperty {
   public Object readSet(DataReader reader, EntityBean bean) throws SQLException {
     try {
       Object value = scalarType.read(reader);
+      if (value == null) {
+        value = checkForEmpty(bean);
+      }
       if (bean != null) {
         setValue(bean, value);
         String json = reader.popJson();
diff --git a/ebean-core/src/test/java/org/tests/json/TestDbJson_List.java b/ebean-core/src/test/java/org/tests/json/TestDbJson_List.java
index 8378888b2..647aa6eff 100644
--- a/ebean-core/src/test/java/org/tests/json/TestDbJson_List.java
+++ b/ebean-core/src/test/java/org/tests/json/TestDbJson_List.java
@@ -234,8 +234,7 @@ public class TestDbJson_List extends BaseTestCase {
     bean.setBeanMap(null);
     DB.save(bean);
 
-    bean = DB.find(EBasicJsonList.class)
-      .setId(bean.getId()).findOne();
+    bean = DB.find(EBasicJsonList.class).setId(bean.getId()).findOne();
 
     assertThat(bean.getFlags()).isEmpty();
     assertThat(bean.getTags()).isEmpty();