Pagination with mongoTemplate

Question

I have a Query with Pageable:

Query query = new Query().with(new PageRequests(page, size))

How can I execute it with MongoTemplate ? I don't see a single method returning Page<T>.

Answer 1

MongoTemplate does not have methods to return Page. The find() methods return an ordinary List.

with(new PageRequests(page, size) is used internally to adjust skip and limit with a MongoDB query (proceeded by a count query I think)

Page can be used in conjunction with MongoDB repositories which is a specialized case of Spring data repositories.

Thus, you'll have to use MongoRepository's Page findAll(Pageable pageable) for paginated results (actually inherited from PagingAndSortingRepository).

Answer 2

It's true that the MongoTemplate doesn't have findXXX with Pageables.

But you can use the Spring Repository PageableExecutionUtils for that.

In your example it would look like this:

Pageable pageable = new PageRequests(page, size);
Query query = new Query().with(pageable);
List<XXX> list = mongoTemplate.find(query, XXX.class);
return PageableExecutionUtils.getPage(
                       list, 
                       pageable, 
                       () -> mongoTemplate.count(query, XXX.class));

Like in the original Spring Data Repository, the PageableExecutionUtils will do a count request and wrap it into a nice Page for you.

Here you can see that spring is doing the same.

Answer 3

Based on d0x's answer and looking at the spring code. I'm using this variation which works off the spring-boot-starter-data-mongodb dependency without needing to add spring data commons.

@Autowired
private MongoOperations mongoOperations;

@Override
public Page<YourObjectType> searchCustom(Pageable pageable) {
    Query query = new Query().with(pageable);
    // Build your query here

    List<YourObjectType> list = mongoOperations.find(query, YourObjectType.class);
    long count = mongoOperations.count(query, YourObjectType.class);
    Page<YourObjectType> resultPage = new PageImpl<YourObjectType>(list , pageable, count);
    return resultPage;
}