Proof of concept to support also bean change detection / changelog on mutable properties

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

@@ -2,6 +2,7 @@ package io.ebeaninternal.server.deploy;
 
 import io.ebean.bean.EntityBean;
 import io.ebean.bean.EntityBeanIntercept;
+import io.ebean.bean.MutableJson;
 import io.ebean.core.type.DataReader;
 import io.ebean.text.TextException;
 import io.ebeaninternal.server.deploy.meta.DeployBeanProperty;
@@ -25,11 +26,11 @@ public class BeanPropertyJsonMapper extends BeanProperty {
   boolean isDirtyValue(Object value, EntityBeanIntercept ebi) {
     // dirty detection based on md5 hash of json content
     final String json = scalarType.jsonMapper(value);
-    final String newHash = Md5.hash(json);
-    final String oldHash = ebi.mutableHash(propertyIndex);
-    if (!Objects.equals(newHash, oldHash)) {
+    final MutableJson oldHash = ebi.mutableHash(propertyIndex);
+    if (oldHash == null || !oldHash.isEqualToJson(json)) {
       ebi.mutableContent(propertyIndex, json); // so we only convert to json once
-      ebi.mutableHash(propertyIndex, newHash); // for dirty detection next time
+      //ebi.mutableHash(propertyIndex, scalarType.jsonMutable(json)); // for dirty detection next time
+      //must be done AFTER persistControllers are called. 
       return true;
     }
     return false;
@@ -43,8 +44,8 @@ public class BeanPropertyJsonMapper extends BeanProperty {
         setValue(bean, value);
         String json = reader.popJson();
         if (json != null) {
-          final String hash = Md5.hash(json);
-          bean._ebean_getIntercept().mutableHash(propertyIndex, hash);
+          final String hash = scalarType.format(value);
+          bean._ebean_getIntercept().mutableHash(propertyIndex, scalarType.jsonMutable(hash));
         }
       }
       return value;

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

@@ -32,8 +32,7 @@ class BindablePropertyJsonInsert extends BindableProperty {
       } else {
         // on insert store MD5 hash and push json
         final String json = prop.format(value);
-        final String hash = Md5.hash(json);
-        bean._ebean_getIntercept().mutableHash(propertyIndex, hash);
+        bean._ebean_getIntercept().mutableHash(propertyIndex, prop.getScalarType().jsonMutable(json));
         request.pushJson(json);
         request.bind(value, prop);
       }

ebean-core/src/main/java/io/ebeaninternal/server/type/ScalarTypeJsonObjectMapper.java

@@ -7,6 +7,8 @@ import com.fasterxml.jackson.databind.JavaType;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.ObjectWriter;
 import com.fasterxml.jackson.databind.introspect.AnnotatedField;
+
+import io.ebean.bean.MutableJson;
 import io.ebean.core.type.DataBinder;
 import io.ebean.core.type.DataReader;
 import io.ebean.core.type.DocPropertyType;
@@ -15,6 +17,7 @@ import io.ebean.text.TextException;
 import io.ebeaninternal.json.ModifyAwareList;
 import io.ebeaninternal.json.ModifyAwareMap;
 import io.ebeaninternal.json.ModifyAwareSet;
+import io.ebeaninternal.server.util.Md5;
 
 import javax.persistence.PersistenceException;
 import java.io.DataInput;
@@ -24,6 +27,7 @@ import java.sql.SQLException;
 import java.sql.Types;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 
 /**
@@ -66,6 +70,66 @@ class ScalarTypeJsonObjectMapper {
     public String jsonMapper(Object value) {
       return formatValue(value);
     }
+    
+    private class Md5MutableJson implements MutableJson {
+
+      private String md5;
+      Md5MutableJson(String json) {
+        md5 = Md5.hash(json);
+      }
+      @Override
+      public boolean isEqualToObject(Object obj) {
+        return true; // we cannot determine differences...
+      }
+
+      @Override
+      public boolean isEqualToJson(String json) {
+        return Md5.hash(json).equals(md5);
+      }
+
+      @Override
+      public Object get() {
+        return null; // cannot create object from json
+      }
+      @Override
+      public void update(Object obj) {
+        md5 = Md5.hash(format(obj));
+      }
+    }
+
+    private class PlainMutableJson implements MutableJson {
+
+      private String originalJson;
+      PlainMutableJson(String json) {
+        originalJson = json;
+      }
+      @Override
+      public boolean isEqualToObject(Object obj) {
+        return isEqualToJson(format(obj));
+      }
+
+      @Override
+      public boolean isEqualToJson(String json) {
+        return Objects.equals(originalJson, json);
+      }
+
+      @Override
+      public Object get() {
+        return parse(originalJson);
+      }
+      @Override
+      public void update(Object obj) {
+        originalJson = format(obj);
+      }
+    }
+    @Override
+    public MutableJson jsonMutable(String originalJson) {
+      if (false) {
+        return new Md5MutableJson(originalJson);
+      } else {
+        return new PlainMutableJson(originalJson);
+      }
+    }
 
     @Override
     public Object read(DataReader reader) throws SQLException {