Spring Mongodb $filter nested object using CriteriaDefinition

Question

I have the following classes

@Document("artists")
public class Artist {
    private String name;
    private List<Album> discography;
    // Getters and Setters
}

public class Album {
    private String title;
    private Instant releaseDate;
    // Getters and Setters
}

My goal is to write an Aggregate function using Spring data mongodb that will allow me to first find an Artist by name, then look through the associated List<Album> and filter its contents based on a date range provided. It should then return a List<Album> with all the instances of Album that fell within that date range.

The main problem I'm having is that an instance of CriteriaDefinition is provided, and I need to construct the Aggregation and $filter conditions using the contents of it.

// A CriteriaDefinition gets passed into this method
// which contains various criteria to search on

Aggregation agg = Aggregation.newAggregation(
    Aggregation.match(criteriaDefinition), //This returns the correct Artist, but with all Album objects
    Aggregation.project()
        .and(filter("album.discography")
        .as("discography")
        .by( //how do use a CriteriaDefinition here? )
    .as("albums")
);

List<Album> albums = mongoTemplate
            .aggregate(agg, Artist.class, Album.class);
return albums;

Is it even possible to filter on CriteriaDefinition?

zpavel · Accepted Answer · 2019-08-01 13:48:54Z

1

You can use unwind operator with a match on subdocuments. For example i filtered artists with name "foobar" and returned its albums with a releaseDate greater than now. Please try :

Aggregation aggregation = newAggregation(
                match(where("name").is("foobar")),
                unwind("discography"),
                match(where("discography.releaseDate").gt(new Date())));

AggregationResults<Album> results = mongoTemplate.aggregate(aggregation, Artist.class, Album.class);
List<Album> albums = results.getMappedResults();

answered Aug 1, 2019 at 13:48

zpavel

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