spring data - Mongodb - findBy Method for nested objects

Question

I have two domain objects,

@Document
public class PracticeQuestion {

     private int userId;
     private List questions;

// Getters and s         


        

Answer 1

You need to use Mongo Aggregation framework :

1) Create custom method for mongo repository : Add custom method to Repository

UnwindOperation unwind =  Aggregation.unwind("questions");
MatchOperation match = Aggregation.match(Criteria.where("userId").is(userId).and("questions.questionId").is(questionID));
Aggregation aggregation = Aggregation.newAggregation(unwind,match);
AggregationResults results = mongoOperations.aggregate(aggregation, "PracticeQuestion",
                PracticeQuestionUnwind.class);
return results.getMappedResults();

2) You need to cretae a class(Because unwind operation has changed the class structure) like below :

public class PracticeQuestionUnwind {
    private String userId;
    private Question questions;

This will give you only those result which matches the provide userId and questionId

Result for userId: 1 and questionId : 111 :

{
    "userId": "1",
     "questions": {
                "questionId": "111",
                "type": "optional"
             }
 }