Sorting MongoDB results using Spring Boot with MongoTemplate

Question

The goal

I'd like to have this query:

db.getCollection("employees").find().sort({
  hire_date: 1
}).limit(10)

written with MongoTemplate in Spring Boot.

The research

I've seen many posts and sites about sorting like e.g.

Attempts

I've tried many ways but I still can't figure out how can I have this done. Some of the things I've tried are listed below:

@Service
public class MongoService {

    @Autowired
    private MongoTemplate mongoTemplate;

    public Document simpleQuery() {

        // 1st
        mongoTemplate.aggregate(Arrays.asList(
                sort(Sorts.ascending("hire_date")),
                limit(10)
        ));

        // 2nd
        mongoTemplate.findAll(Employee.class).sort(new BasicDBObject("hire_date", 1));

        // 3rd
        mongoTemplate.findAll(Employee.class).sort((o1, o2) -> o1.getHire_date() > o2.getHire_date());

        // and more...
    }
}

The solution might be pretty simple I guess, just like the query itself, but these are my first steps on that kind of ground. Thank you in advance for any help on this one.

didn't have time to try it out unfortunately, I'll check later today. — big_OS, Aug 18 '20 at 06:18

score 1 · Accepted Answer · answered Aug 16 '20 at 17:22

1

Try this,

Aggregation aggregation = Aggregation.newAggregation(
    sort(Sort.Direction.ASC, "hire_date"),
    limit(10)
).withOptions(AggregationOptions.builder().allowDiskUse(Boolean.TRUE).build());

mongoTemplate.aggregate(aggregation, mongoTemplate.getCollectionName(Employee.class), Object.class).getMappedResults();

answered Aug 16 '20 at 17:22

varman

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yes, it helped :) but there is one weird behaviour - it wouldn't let me use `allowDiskUse` when I tried to write it by myself but when I copy-pased your answer, it worked – big_OS Aug 22 '20 at 08:26
let me know why are we using `allowDiskUsage` here? – big_OS Aug 22 '20 at 08:27
1

thank you. This https://stackoverflow.com/a/37805720/7975771 answer has clear explanation. Let me know if you have any doubts. I will try my best to sort it out – varman Aug 22 '20 at 08:31

score 1 · Answer 2 · answered Aug 16 '20 at 17:23

You can do as below.

You need a query part

//As you need to match all
Query query = new Query()

You need to add sorting option

//You need to use Sort class with sorting order, field name to be used for sorting
query.with(new Sort(Sort.Direction.ASC, "hire_date"));

You need to add pagination option

final Pageable pageableRequest = PageRequest.of(0, 10);
query.with(pageableRequest);

You need to add a model

mongoTemplate(query, Employee.class)

Sample refer

Another useful answer

Sorting MongoDB results using Spring Boot with MongoTemplate

2 Answers2