Getting a tag as additional object returned in json while searching images by that tag - spring

Question

Okay first of all I don't even know how to describe it in one sentence to ask google ( yes I did and I failed).
I have this gallery spring boot back-end application.
So there is Image class and Tag class between which is manytomany relationship.
Here are these classes:
#Entity
#Table(name = "image")
#JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class)
public class Image {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "image_id")
private int id;
#Column(name = "name")
private String name;
#Column(name = "description")
private String description;
#Column(name = "height")
private int height;
#Column(name = "width")
private int width;
#Column(name = "date")
private Date date;
#ManyToMany(cascade = {
CascadeType.PERSIST,
CascadeType.MERGE
})
#JoinTable(
name="image_tag",
joinColumns = #JoinColumn(name="image_id"),
inverseJoinColumns = #JoinColumn(name = "tag_id")
)
private Set<Tag> tags = new HashSet<>();
// getters / setters further
And this is my tag class:
#Entity
#Table(name = "tag")
public class Tag {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "tag_id")
private int id;
#Column(name ="name", length= 50)
private String name;
#Column(name = "createddate", length = 100)
private Date createdDate;
public Tag(String name) {
this.name = name;
}
public Tag() {
}
#Override
public String toString() {
return "Tag{" +
"id=" + id +
", name='" + name + '\'' +
", createdDate=" + createdDate +
'}';
}
#ManyToMany(mappedBy = "tags")
private Set<Image> images = new HashSet<>();
This is how I get my Images by tag's name:
#Transactional
#Override
public List<Image> findByTag(String tag) {
Session session = entityManager.unwrap(Session.class);
Query<Image> query = session.createQuery("from Image as img inner join
img.tags as tags where tags.name=:tagname");
query.setParameter("tagname", tag);
List<Image> images = query.getResultList();
return images;
}
The problem is that whenever I make a get request with tag's name to get Images. Next to every Image object I receive there will also be that tag object with the name I used to look for images.
{
"#id": 2,
"id": 6,
"name": "peoples",
"description": "some people hanging",
"height": 501,
"width": 780,
"date": "2019-09-02T12:34:23.000+0000",
"tags": [
// there are more tags here I'm just saving space
{
"id": 7,
"name": "joy",
"createdDate": "2019-09-03T12:27:49.000+0000",
"images": [
2
]
}
],
"categories": [],
"picture": " byte array of picture"
},
Aand this is where magic happens, this object will be next to every Image object in Json response.
{
"id": 7,
"name": "joy",
"createdDate": "2019-09-03T12:27:49.000+0000",
"images": [
2
]
}
I'm using Angular for front end and I can't fetch Images like this because I'll get an error because there will be tag object there.
Really hoping to figure this out!
#GetMapping("/tags/{tagname}")
public List<Image> getImageByTag(#PathVariable("tagname") String tagName){
return imageService.findByTag(tagName);
}
And this is that service:
#Override
public List<Image> findByTag(String tag) {
return imageDao.findByTag(tag);
}

Answer 1

It's more like a json serialize problem. If you are using jackson as I guessed, you can try to manually control the output by following:
public class Image {
#JsonBackReference
private Set<Tag> tags = new HashSet<>();
}
If you do need to include tag in some occasions, you might have to implement a JSON view