CODEWITHSUNDEEP
sqlspringspring-bootjpaspring-data-jpa
63350541
63350541

Reputation: 37

Spring Data: JPA repository return Map instead of List?

I have such Query where from which I want to extract movie title and its rating

   @Query(value ="SELECT m.title, avg(r.rating) " +
        "FROM movies m " +
        "INNER JOIN " +
        "ratings r " +
        "ON m.movieid = r.movieid " +
        "WHERE m.genres LIKE %:genre% " +
        "GROUP BY m.title " +
        "ORDER BY avg(r.rating) DESC " +
        "LIMIT 10",
        nativeQuery = true)
 List<Movies> topTenMoviesByGenreLikeIgnoreCase(@Param("genre") String genre);

But this list obviously cannot store the resultSet with 2 values

After learning about it I've found e.g. this link Spring Data: JPA repository findAll() to return *Map instead of List? but their implementation seems unclear to me.

I don't understand where do they get the Long value from in the first link

default Map<Long, TransactionModel> findByClientIdMap(Long id) {
    return findByClientId(id).stream().collect(Collectors.toMap(TransactionModel::getId, v -> v));
}

How do I create my map?

default Map<Movies, Float> topTenMoviesByGenreLikeIgnoreCaseMap(@Param("genre") String genre) {
    return topTenMoviesByGenreLikeIgnoreCase(genre).stream().collect(Collectors.toMap());
}

Movies class:

@Entity
public class Movies {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer movieid;

private String title;
private String genres;

@OneToMany(mappedBy = "movieid")
private Set<Ratings> rates = new HashSet<>();

public Movies() {
}

public Movies(String title, String genres) {
    this.title = title;
    this.genres = genres;
}

/*Getters and Setters for variables*/

public Set<Ratings> getRates() {
    return rates;
}

public void setRates(Set<Ratings> rates) {
    this.rates = rates;
}
}

Ratings class:

@Entity
public class Ratings {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer rateid;

@ManyToOne
@JoinColumn(name = "movieid")
private Movies movieid;

@ManyToOne
@JoinColumn(name = "userid")
private Usrs userid;

private float rating;
private Integer timestamp;

public Ratings() {
}

public Ratings(Movies movieid, Usrs userid, float rating, Integer timestamp)
{
    this.movieid = movieid;
    this.userid = userid;
    this.rating = rating;
    this.timestamp = timestamp;
}
/*Getters and Setters for variables*/
}

Upvotes: 0

Views: 3379

Answers (2)

Oleksii Valuiskyi
Oleksii Valuiskyi

Reputation: 2851

You can use Object[] as a query result this way

@Query(value ="SELECT m.title, avg(r.rating) " +
        "FROM movies m " +
        "INNER JOIN " +
        "ratings r " +
        "ON m.movieid = r.movieid " +
        "WHERE m.genres LIKE %:genre% " +
        "GROUP BY m.title " +
        "ORDER BY avg(r.rating) DESC " +
        "LIMIT 10",
        nativeQuery = true)
 List<Object[]> topTenMoviesByGenreLikeIgnoreCase(@Param("genre") String genre);

So then

default Map<String, Float> topTenMoviesByGenreLikeIgnoreCaseMap(@Param("genre") String genre) {
    return topTenMoviesByGenreLikeIgnoreCase(genre)
            .stream()
            .collect(Collectors.toMap((arr->arr[0].toString()), (arr->Float.valueOf(arr[1].toString()))));
}

As you can see topTenMoviesByGenreLikeIgnoreCaseMap returns Map where the movie title is the key. To make a Movie entity the key you should use a JPQL query instead of a native one.

Upvotes: 1

Chandra Kant
Chandra Kant

Reputation: 207

Try out this:

@Query(value ="SELECT m.title as title, r.avg(rating) as rates " +
    "FROM movies m " +
    "INNER JOIN " +
    "ratings r " +
    "ON m.movieid = r.movieid " +
    "WHERE m.genre = LIKE %:genre% " +
    "GROUP BY r.avg(rating) " +
    "ORDER BY r.avg(rating) DESC " +
    "LIMIT 10",
    nativeQuery = true)

List<Movies> topTenMoviesByGenreLikeIgnoreCase(@Param("genre") String genre);    



default Map<Movies, Set<Ratings>> topTenMoviesByGenreLikeIgnoreCaseMap(@Param("genre") String genre) {
    return topTenMoviesByGenreLikeIgnoreCase(genre).stream().collect(
                                                            Collectors.toMap(
                                                            tuple -> (tuple.getTitle(),
                                                            tuple -> (tuple.getRates())
                                                         ));
}

Upvotes: 0

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