How do I execute a MongoDB js script using the Java MongoDriver

Question

I have implemented a JavaScript function inside the Mongodb server using this example.

It works fine when I use mongo shell, but I want to run it from inside a Java

Answer 1

You should use DB.eval(), see the api docs and make sure that you don't do string concatenation. Pass the variables through instead.

I think your answer is probably the same answer as this other one on StackOverflow.

Answer 2

@Autowired
private MongoOperations mongoOperations;

private final BasicDBObject basicDBObject = new BasicDBObject();

@PostConstruct
private void initialize() {
    basicDBObject.put("eval", "function() { return db.loadServerScripts(); }");
    mongoOperations.executeCommand(basicDBObject);
}

private void execute() {
    basicDBObject.put("eval", "function() { return echoFunction(3); }");
    CommandResult result = mongoOperations.executeCommand(basicDBObject);
}

And then you can use something like:

ObjectMapper mapper = new ObjectMapper();

And MongoOperation's:

mongoOperations.getConverter().read(CLASS, DBOBJECT);

Just try to have some workaround depends on your requirements

Answer 3

The previous answers does not work in MongoDB 3.4+. Th proper way to do this in version 3.4 and above is to create a BasicDBObject and use it as the parameter of Database.runCommand(). Here's an example.

final BasicDBObject command = new BasicDBObject();
            command.put("eval", String.format("function() { %s return;}}, {entity_id : 1, value : 1, type : 1}).forEach(someFun); }", code));
            Document result = database.runCommand(command);

Answer 4

Since MongoDB 4.2 the eval command is removed (it was deprecated in 3.0). There is no more way to eval JavaScript scripts into MongoDB from the Java Driver.

See https://docs.mongodb.com/manual/reference/method/db.eval/