diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/query/json/base/JsonQueryERElement.java b/src/main/java/org/gcube/informationsystem/resourceregistry/query/json/base/JsonQueryERElement.java
index bebf110..374a15e 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/query/json/base/JsonQueryERElement.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/query/json/base/JsonQueryERElement.java
@@ -97,53 +97,49 @@ public abstract class JsonQueryERElement {
 				stringBuffer.append(queryLogicalOperator.getLogicalOperator());
 			}
 			
-			if(QueryLogicalOperator.getOperators().contains(fieldName)) {
-				QueryLogicalOperator innnerQueryLogicalOperator = QueryLogicalOperator.getQueryLogicalOperator(fieldName);
-				JsonNode node = objectNode.get(fieldName);
-				stringBuffer.append(addConstraint(node, innnerQueryLogicalOperator, fieldNamePrefix)); 
-			}else {
-				stringBuffer.append(getNameValueToMatch(objectNode, fieldName, fieldNamePrefix));
-			}
+			JsonNode node = objectNode.get(fieldName);
+			stringBuffer.append(evaluateNode(node, fieldName, fieldNamePrefix));
 		}
 		
 		return stringBuffer;
 	}
 	
-	private StringBuffer getNameValueToMatch(JsonNode jsonNode, String fieldName, String fieldNamePrefix) throws InvalidQueryException {
+	
+	protected StringBuffer evaluateNode(JsonNode jsonNode, String fieldName, String fieldNamePrefix) throws InvalidQueryException {
 		StringBuffer stringBuffer = new StringBuffer();
 		
-		JsonNode gotJoJsonNode = jsonNode.get(fieldName);
+		if(QueryLogicalOperator.getOperators().contains(fieldName)) {
+			QueryLogicalOperator queryLogicalOperator = QueryLogicalOperator.getQueryLogicalOperator(fieldName);
+			stringBuffer.append(addConstraint(jsonNode, queryLogicalOperator, fieldNamePrefix)); 
+			return stringBuffer;
+		}
 		
-		if(gotJoJsonNode.isContainerNode()) {
+		if(QueryConditionalOperator.getOperators().contains(fieldName)) {
+			QueryConditionalOperator queryConditionalOperator = QueryConditionalOperator.getQueryComparisonOperator(fieldName);
 			
-			if(gotJoJsonNode.isArray()) {
-				throw new InvalidQueryException("Array not supported for " + fieldName); 
-			}
-			
-			if(gotJoJsonNode.isObject()) {
-				
-				for(QueryConditionalOperator queryComparisonOperator : QueryConditionalOperator.values()) {
-					if(gotJoJsonNode.has(queryComparisonOperator.operator)) {
-						// TODO
-					}
-				}
-				
-				StringBuffer newPrefix = new StringBuffer();
-				if(fieldNamePrefix!=null) {
-					newPrefix.append(fieldNamePrefix);
-					newPrefix.append(".");
-				}
-				newPrefix.append(fieldName);
-				
-				stringBuffer.append(addConstraint(gotJoJsonNode, null, newPrefix.toString()));
-				return stringBuffer;
-			}
-			
-		} 
+		}
 		
-		addNameToCompare(stringBuffer, fieldName, fieldNamePrefix);
-		String value = jsonNode.get(fieldName).asText();
-		addValueToMatch(stringBuffer, gotJoJsonNode, value);
+		if(jsonNode.isArray()) {
+			return stringBuffer; 
+		}
+		
+		if(jsonNode.isObject()) {
+			StringBuffer newPrefix = new StringBuffer();
+			if(fieldNamePrefix!=null) {
+				newPrefix.append(fieldNamePrefix);
+				newPrefix.append(".");
+			}
+			newPrefix.append(fieldName);
+			
+			stringBuffer.append(addConstraint(jsonNode, null, newPrefix.toString()));
+			return stringBuffer;
+		}
+		
+		if(jsonNode.isTextual() || jsonNode.isNumber()) {
+			addNameToCompare(stringBuffer, fieldName, fieldNamePrefix);
+			String value = jsonNode.asText();
+			addValueToMatch(stringBuffer, jsonNode, value);
+		}
 		
 		return stringBuffer;
 	}