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Many-To-One with join table in sleeping resource classes for JAX-RS using Jersey

I am using a RESTful web service using Jersey. I am using hibernate to communicate with a database (mySQL). My hibernation resource classes include:

@Entity
public class Activity {

    @Id
    @GeneratedValue
    private long id;

@ManyToOne
    @JoinTable(name="category_activity",
    joinColumns={@JoinColumn(name="activities_id")},
    inverseJoinColumns={@JoinColumn(name="Category_id")})
    private Category category;
}

and class Category:

@Entity
public class Category {

    @Id
    @GeneratedValue
    private long id;

    @OneToMany
    @Fetch(FetchMode.JOIN)
    @JoinTable(name = "category_activity",
    joinColumns = { @JoinColumn(name = "Category_id") }, 
    inverseJoinColumns = { @JoinColumn(name = "activities_id") })
    @JsonIgnore
    private Collection<Activity> activities;
}

I used this query to get attributes:

session.createQuery("from Activity a join a.category cs where cs.id= :categoryId order by a.key").setLong("categoryId", categoryId).list();

The result in JSON format is incorrect:

[[{"id":26,"key":"other","name":"Other","cost":100.0,"category":{"id":10,"name":"General","description":""}},{"id":10,"name":"General","description":""}]]

As you can see, the category is printed 2 times, and we have an extra [] around it. When I use another one-to-many relationship mechanism in a category class, for example:

@OneToMany(targetEntity = Activity.class, mappedBy = "category", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
@JsonIgnore
private Collection<Project> activities;

And in the Activity class:

@ManyToOne(optional = false)
    private Category category;

And this request:

session.createQuery("from Activity as a where a.category.id= :categoryId order by a.key").setLong("categoryId", categoryId).list();

Everything works perfectly. But I need to use the connection table because I cannot change the database.

The correct result should look like this:

[{"id":26,"key":"other","name":"Other","cost":100.0,"category":{"id":10,"name":"General","description":""}}]

I appreciate any help.

+5
source
1

, . , , .

( , , , , mappedBy:

public class Activity {

    @ManyToOne // owner side: it doesn't have mappedBy, and can decide how the association is mapped: with a join table
    @JoinTable(name="category_activity",
               joinColumns={@JoinColumn(name="activities_id")},
               inverseJoinColumns={@JoinColumn(name="Category_id")})
    private Category category;
}

public class Category {
    @OneToMany(mappedBy = "category") // inverse side: it has a mappedBy attribute, and can't decide how the association is mapped, since the other side already decided it.
    @Fetch(FetchMode.JOIN)
    @JsonIgnore
    private Collection<Activity> activities;
}

EDIT:

, , , , select:

select a from Activity as a where a.category.id= :categoryId order by a.key
+9

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