added writeable check to prevent dirty flushing trying to write on readonly fields

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/AbstractRelationshipFieldAccessor.java

@@ -28,6 +28,10 @@ public abstract class AbstractRelationshipFieldAccessor<ENTITY,STATE,TARGET,TSTA
         this.type = type;
     }
 
+    @Override
+    public boolean isWriteable(ENTITY entity) {
+        return true;
+    }
 
     protected STATE checkUnderlyingNode(ENTITY entity) {
         if (entity==null) throw new IllegalStateException("Entity is null");

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/DefaultEntityStateAccessors.java

@@ -76,6 +76,13 @@ public class DefaultEntityStateAccessors<ENTITY extends NodeBacked, STATE> imple
         });
     }
 
+    @Override
+    public boolean isWritable(Field field) {
+        final FieldAccessor<ENTITY, ?> accessor = accessorFor(field);
+        if (accessor == null) return true;
+        return accessor.isWriteable(entity);
+    }
+
     @Override
     public Object getValue(final Field field) {
         final FieldAccessor<ENTITY, ?> accessor = accessorFor(field);

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/DetachableEntityStateAccessors.java

@@ -31,6 +31,11 @@ public class DetachableEntityStateAccessors<ENTITY extends NodeBacked, STATE> im
         this.delegate = delegate;
     }
 
+    @Override
+    public boolean isWritable(Field field) {
+        return delegate.isWritable(field);
+    }
+
     @Override
     public ENTITY getEntity() {
         return delegate.getEntity();
@@ -61,7 +66,7 @@ public class DetachableEntityStateAccessors<ENTITY extends NodeBacked, STATE> im
     public Object setValue(final Field field, final Object newVal) {
         if (!transactionIsRunning()) {
             final ENTITY entity = getEntity();
-            if (!isDirty(field)) {
+            if (!isDirty(field) && isWritable(field)) {
                 Object existingValue;
                 if (entity.hasUnderlyingNode()) existingValue = unwrap(delegate.getValue(field));
                 else {

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/EntityStateAccessors.java

@@ -18,6 +18,7 @@ public interface EntityStateAccessors<ENTITY extends NodeBacked> {
     void setNode(Node node);
 
     Object getValue(Field field);
+    boolean isWritable(Field field);
 
     Object setValue(Field field, Object newVal);
 

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/FieldAccessor.java

@@ -1,11 +1,10 @@
 package org.springframework.datastore.graph.neo4j.fieldaccess;
 
-import org.springframework.datastore.graph.api.NodeBacked;
-
 public interface FieldAccessor<ENTITY, TARGET> {
 
 	Object setValue(ENTITY entity, Object newVal);
 
 	Object getValue(ENTITY entity);
 
+    boolean isWriteable(ENTITY entity);
 }

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/IdFieldAccessor.java

@@ -17,6 +17,11 @@ public class IdFieldAccessor implements FieldAccessor<NodeBacked, Object> {
         this.field = field;
     }
 
+    @Override
+    public boolean isWriteable(NodeBacked nodeBacked) {
+        return false;
+    }
+
     @Override
     public Object setValue(final NodeBacked nodeBacked, final Object newVal) {
         return doReturn(null);

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/NodePropertyFieldAccessor.java

@@ -17,6 +17,11 @@ public class NodePropertyFieldAccessor implements FieldAccessor<NodeBacked, Obje
         this.field = field;
     }
 
+    @Override
+    public boolean isWriteable(NodeBacked nodeBacked) {
+        return true;
+    }
+
     @Override
     public Object setValue(final NodeBacked nodeBacked, final Object newVal) {
         nodeBacked.getUnderlyingNode().setProperty(getPropertyName(),newVal);

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/OneToNRelationshipEntityFieldAccessor.java

@@ -26,6 +26,11 @@ public class OneToNRelationshipEntityFieldAccessor extends AbstractRelationshipF
         throw new InvalidDataAccessApiUsageException("Cannot set read-only relationship entity field.");
     }
 
+    @Override
+    public boolean isWriteable(NodeBacked nodeBacked) {
+        return false;
+    }
+
     @Override
     public Object getValue(final NodeBacked entity) {
         checkUnderlyingNode(entity);

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/ReadOnlyOneToNRelationshipFieldAccessor.java

@@ -15,7 +15,12 @@ public class ReadOnlyOneToNRelationshipFieldAccessor extends OneToNRelationshipF
         super(type,direction,elementClass, graphDatabaseContext);
 	}
 
-	public Object setValue(final NodeBacked entity, final Object newVal) {
+    @Override
+    public boolean isWriteable(NodeBacked nodeBacked) {
+        return false;
+    }
+
+    public Object setValue(final NodeBacked entity, final Object newVal) {
 		throw new InvalidDataAccessApiUsageException("Cannot set read-only relationship entity field.");
 	}
 

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/TransientFieldAccessor.java

@@ -21,6 +21,11 @@ public class TransientFieldAccessor implements FieldAccessor<NodeBacked, Object>
         return newVal;
     }
 
+    @Override
+    public boolean isWriteable(NodeBacked nodeBacked) {
+        return true;
+    }
+
     @Override
     public Object getValue(final NodeBacked nodeBacked) {
         return null;

src/main/java/org/springframework/datastore/graph/neo4j/fieldaccess/TraversalFieldAccessor.java

@@ -33,6 +33,11 @@ public class TraversalFieldAccessor implements FieldAccessor<NodeBacked, Object>
         this.fieldTraversalDescriptionBuilder = createTraversalDescription(graphEntityTraversal);
     }
 
+    @Override
+    public boolean isWriteable(NodeBacked nodeBacked) {
+        return false;
+    }
+
     @Override
     public Object setValue(final NodeBacked nodeBacked, final Object newVal) {
         throw new InvalidDataAccessApiUsageException("Cannot set readonly traversal description field " + field);