diff --git a/src/main/java/org/gcube/application/geoportal/common/model/rest/QueryRequest.java b/src/main/java/org/gcube/application/geoportal/common/model/rest/QueryRequest.java
index 8a58311..ab95885 100644
--- a/src/main/java/org/gcube/application/geoportal/common/model/rest/QueryRequest.java
+++ b/src/main/java/org/gcube/application/geoportal/common/model/rest/QueryRequest.java
@@ -1,6 +1,7 @@
 package org.gcube.application.geoportal.common.model.rest;
 
 import lombok.Data;
+import org.bson.Document;
 
 import java.util.List;
 
@@ -20,8 +21,8 @@ public class QueryRequest {
         private String json;
         private List<String> fields;
     }
-    private String filter;
-    private String transformation;
+    private Document filter;
+    private Document transformation;
     private OrderedRequest ordering;
     private PagedRequest paging;
 }