使用 Jackson ObjectIdGenerator 将 Json 转换为集合时出现问题

Question

我正在尝试将以下 JSON 转换为 Java

中的集合

"films" : [
        {
            "fid" : 1, 
            "title" : "The Platform", 
            "year": 2019, 
            "genre": [1,2,3], 
            "director": 1, 
            "cast": [2,3,4] , 
            "description": "A vertical prison with one cell per level. Two people per cell. One only food platform and two minutes per day to feed from up to down. An endless nightmare trapped in The Hole."
        }
],

"tvseries" : [
        {
            "tid" : 1, 
            "title" : "Breaking Bad", 
            "year": 2008, 
            "genre": [9,5,3],
            "creator": 13, 
            "cast": [14,15,16] , 
            "description": " A high school chemistry teacher diagnosed with inoperable lung cancer turns to manufacturing and selling methamphetamine in order to secure his family's future."
        }
],
"people" : [
        { "pid": 1, "name" : "Galder Gaztelu-Urrutia" }
],

 "genres" : [
        { "gid": 1, "genre": "Horror" }
]

以上只是部分数据的示例。我的特殊问题是电影 class，特别是以下错误："Problem deserializing property 'director' (expected type: [simple type, class assignment4.model.Person]; actual type: assignment4.model.Film)"

这是我的 class 电影和人物结构：

public abstract class Media {
private String title;
private int year;
private String description;
private ArrayList<Genre> genre = new ArrayList<Genre>();
private ArrayList<Person> cast = new ArrayList<Person>();
}

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "fid")
public class Film extends Media {
    private int fid;
    private Person director;

    @Override
    public int hashCode() {
        return Arrays.hashCode(new Object[] { getFid(),  getTitle() });
    }

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "pid")
public class Person {
private int pid;
private String name;

@Override
public int hashCode() {
    return Arrays.hashCode(new Object[] { getPid(),  getName() });
}

public class Collection {

    private Set<Film> films = new TreeSet<Film>();
    private Set<Genre> genres = new TreeSet<Genre>();
    private Set<Person> people = new TreeSet<Person>();
    private Set<Profile> profiles = new TreeSet<Profile>();
    private Set<TV> tvseries = new TreeSet<TV>();
}

所有 classes 都有 getter 和各种属性的设置器。能想到的都试过了，就是想不通为什么搞不定导演。

Answer 1

您应该在您的 POJO @JsonIdentityInfo 注释中设置 scope 属性：

@JsonIdentityInfo(
    generator = ObjectIdGenerators.PropertyGenerator.class, 
    property = "pid", scope = Person.class)
public class Person {
    private int pid;
    private String name;
// getters/setters/hashcode, etc. ...
}

@JsonIdentityInfo(
    generator = ObjectIdGenerators.PropertyGenerator.class, 
    property = "gid", scope = Genre.class
)
public class Genre {
    private int gid;
    private String genre;
// getters/setters/hashcode, etc. ...
}

@JsonIdentityInfo(
    generator = ObjectIdGenerators.PropertyGenerator.class, 
    property = "fid", scope = Film.class
)
public class Film extends Media {
    private int fid;
    private String title;
    private Person director;
// getters/setters/hashcode, etc. ...
}

使用 Jackson ObjectIdGenerator 将 Json 转换为集合时出现问题

Problem Converting Json to Collection with Jackson ObjectIdGenerator

java

json

jackson

jackson-databind