Search for Entity with foreign key

Hibernate ORM
1

Hello there,
I’m new to hibernate and using it with MySQL.

I have two entities mapped together.

@Entity
public class Game extends AbstractDefaultEntity implements java.io.Serializable {
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private Integer id;

	@JsonManagedReference
	@NotNull
	@ManyToOne(fetch = FetchType.EAGER)
	@JoinColumn(name = "seasonid")
	private Season season;

	@NotEmpty(message = "Please enter title")
	private String title;

	@NotNull
	private Date date;

	private Time time;

	private Integer maxOrder;

        @JsonManagedReference
	@OneToMany(fetch = FetchType.LAZY)
	@JoinColumn(name = "gameid")
	private Set<Ticket> tickets;


@Entity
public class Ticket extends AbstractDefaultEntity implements java.io.Serializable {
	@Id
	@GeneratedValue(strategy= GenerationType.IDENTITY)
	private Integer id;

	@NotNull
	@JsonManagedReference
	@OneToOne(fetch = FetchType.LAZY)
	@JoinColumn(name = "gameid")
	@NaturalId
	private Game game;

	@NotEmpty(message = "Please enter title")
	private String title;

	private Float price;
	private Integer maxorder;
	private String type;

Each game can have 0-n tickets.
When i add a ticket and select the game, the reference is build up correctly.

{
    "id": 1,
    "season": {
        "id": 1,
        "title": "Saison 2021/2022",
        "active": "true"
    },
    "title": "FC Bayern-BVB",
    "date": "2020-04-20",
    "time": "17:00",
    "maxOrder": 1,
    "tickets": [
        {
            "id": 1,
            "title": "Stehplatz München",
            "price": 20.0,
            "maxorder": 1,
            "type": "sitting",
            "displayTitle": "Stehplatz München"
        },
        {
            "id": 2,
            "title": "Sitzplatz München",
            "price": 50.0,
            "maxorder": 1,
            "type": "sitting",
            "displayTitle": "Sitzplatz München"
        }
    ]
}

But now I want to know, which tickets belong to Gameid=1.
I’m using the CriteriaBuilder and get the error “Parameter value [1] did not match expected type”
I can not use static querys as I have to filter the fields dynamically given by the UI.
The incoming parameters can change, so I have to select by title one time or by gameid the other time

public static Predicate getListFilter(UriInfo uriInfo, Root root, CriteriaBuilder cb, CriteriaQuery query) {
        List<Predicate> predicateList = new ArrayList<>();

        if (!uriInfo.getQueryParameters().containsKey("filter")) {
            System.out.println("NO Filter found");
            return null;
        }
        String filter = uriInfo.getQueryParameters().getFirst("filter");

        JsonObject jsonFilter = new JsonParser().parse(filter).getAsJsonObject();

        Set<Map.Entry<String, JsonElement>> entrySet = jsonFilter.entrySet();
        for(Map.Entry<String, JsonElement> entry : entrySet) {

            String filterField = entry.getKey();
            String filterValue = entry.getValue().toString().replace("\"","");
            System.out.println("############");
            System.out.println(filterField);
            System.out.println(filterValue);
            //if (filter.value)

            if (!filterValue.equals("")) {
                //Predicate pred = cb.like(root.get(filterField), "%" + filterValue + "%");
                Predicate pred = cb.equal(root.get(filterField), filterValue);
                predicateList.add(pred);
            }
        }
        Predicate allPredicates = cb.and(predicateList.toArray(new Predicate[0]));
        return allPredicates;
    }
2

The id of Game is of the type Integer, so you will first have to transform your filter value to the proper type e.g. by using Integer.valueOf.

3

Thank you.
It’s working.

But now, i need to know the datatype of the column.

if (root.get(filterField).getJavaType().equals(String.class)) {
                    pred = cb.like(root.get(filterField), "%" + filterValue + "%");
                }
                System.out.println("TYPE ");
                System.out.println(root.get(filterField).getJavaType());
                if (root.get(filterField).getJavaType().equals(Integer.class)) {
                    pred = cb.equal(root.get(filterField), Integer.valueOf(filterValue));
                }

GetJavaType() returns the Type of the Entity, not from the attribute.
How can I get the datatype?

4

If this is an association, you will have to use the identifier type of that entity type for converting the value, but beware, that comparing entities to integer values might be a bad idea. I would suggest you materialize the entity by using entityManager.getReference and pass that.