JMeter MongoDB Where Clause NOT Working with $gt $lt - mongodb

Question

I am getting below error, when I try to use greater than or less than in mongoDB where clause: Any idea how to avoid this?
Response message: javax.script.ScriptException: groovy.lang.MissingPropertyException: No such property: gt for class: Script117
Below is my Full Groovy Code till now:
Everything works except the GREATER THAN (or lt) query filter:
import com.mongodb.DB;
import org.apache.jmeter.protocol.mongodb.config.MongoDBHolder;
import com.mongodb.MongoClient;
import com.mongodb.ServerAddress;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.DBCollection;
import com.mongodb.*;
//======================================================================
MongoClient mongoClient = new MongoClient(new ServerAddress("${serverIP}", ${serverPort}));
DB db = mongoClient.getDB("${mongodb}");
DBCollection coll = db.getCollection("${collectionName}");
StringBuilder rs = new StringBuilder();
rs.append("Collection: \n");
BasicDBObject allQuery = new BasicDBObject();
BasicDBObject fields = new BasicDBObject();
fields.put("name", 1); //projected fields
fields.put("age", 1); //projected fields
fields.put("eyeColor", 1); //projected fields
fields.put("balance", 1); //projected fields
BasicDBObject whereQuery = new BasicDBObject();
//whereQuery.put("gender", "female");
whereQuery.put("age", new BasicDBObject("$gt", 30));
DBCursor cursor = coll.find(whereQuery, fields);
while( cursor.hasNext() ) {
DBObject obj = cursor.next();
rs.append(obj.toString());
rs.append("\n");
}
rs.toString();
//String variable at the LAST LINE of this Groovy script will be displayed in Results tab, even if no Display methods are invoked !!!

Answer 1

The error message: groovy.lang.MissingPropertyException, is thrown when:
An exception occurred while a dynamic property dispatch fails with an
unknown property.
Note: the Missing*Exception classes are named for consistency and to avoid conflicts with JDK exceptions of the same name.
The attempt to insert the "age" as key and the new BasicDBObject("$gt",30) as a value, cause to the exception you get, because the JVM looks for a property calls gt which is not exists.
The put method means: Sets a name/value pair in this object.
In the code you have you intend to append the search criteria, and not to put it.
Related to the code you have, I would recommend replacing the using of put method with append.
This is your code:
BasicDBObject whereQuery = new BasicDBObject();
//whereQuery.put("gender", "female");
whereQuery.put("age", new BasicDBObject("$gt", 30));
If you replace the:
whereQuery.put("age", new BasicDBObject("$gt", 30));
With:
whereQuery.append("age", new BasicDBObject("$gt", 30));
Another suggestion you can use is the Criteria.where syntax,
which is much more readable.
def query = Query.query(Criteria.where('gender').is('female').and('age')
.gt(30))
collection.find(query, fields)
Another small issue, because your code is written in Groovy you should not finish each line with ;

Answer 2

Have you tried using single quotes so groovy doesn't think you're doing string templating?
whereQuery.put("age", new BasicDBObject('$gt', 30))
// ^ ^ here

Answer 3

You should be avoiding:
Referring JMeter Variables as ${var}
Using $var structures
as they have special meaning in Groovy, so:
Replace these ${serverIP} with vars.get("serverIP"), ${mongodb} with vars.get("mongodb"), etc.
Replace double quotes with single quotes, especially in the line where you use $gt function
(Optional) semicolons at the lines end are not necessary
References:
Groovy Differences with Java
How to Load Test MongoDB with JMeter