#1990 - NPE with @Cache and setting naturalKey to null

src/main/java/io/ebeaninternal/server/core/PersistRequestBean.java

@@ -1399,7 +1399,8 @@ public final class PersistRequestBean<T> extends PersistRequest implements BeanP
               changes.put(property.getName(), val);
               if (property.isNaturalKey()) {
                 updateNaturalKey = true;
-                changeSet.addNaturalKeyPut(beanDescriptor, key, val.toString());
+                String valStr = (val == null) ? null : val.toString();
+                changeSet.addNaturalKeyPut(beanDescriptor, key, valStr);
               }
             }
           }

src/test/java/org/tests/model/basic/cache/OCachedApp.java

@@ -10,7 +10,7 @@ import javax.persistence.UniqueConstraint;
 @UniqueConstraint(columnNames = "app_name")
 public class OCachedApp extends OCacheBase {
 
-  private final String appName;
+  private String appName;
 
   public OCachedApp(String appName) {
     this.appName = appName;
@@ -19,4 +19,8 @@ public class OCachedApp extends OCacheBase {
   public String getAppName() {
     return appName;
   }
+
+  public void setAppName(String appName) {
+    this.appName = appName;
+  }
 }

src/test/java/org/tests/model/basic/cache/TestNatKeyCacheWhenNull.java

@@ -0,0 +1,41 @@
+package org.tests.model.basic.cache;
+
+import io.ebean.BaseTestCase;
+import io.ebean.DB;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class TestNatKeyCacheWhenNull extends BaseTestCase {
+
+  public static final String WILL_CHANGE_TO_NULL = "WillChangeToNull";
+
+  @Test
+  public void updateToNull() {
+
+    OCachedApp app = setup();
+
+    // act
+    app.setAppName(null);
+    app.save();
+
+    final OCachedApp foundAfter = DB.find(OCachedApp.class)
+      .where().eq("appName", WILL_CHANGE_TO_NULL)
+      .findOne();
+
+    assertThat(foundAfter).isNull();
+    app.delete();
+  }
+
+  private OCachedApp setup() {
+    OCachedApp app = new OCachedApp(WILL_CHANGE_TO_NULL);
+    app.save();
+
+    final OCachedApp foundBefore = DB.find(OCachedApp.class)
+      .where().eq("appName", WILL_CHANGE_TO_NULL)
+      .findOne();
+
+    assertThat(foundBefore).isNotNull();
+    return app;
+  }
+}