当我尝试用帖子保存我的实体(“章节”)时,我收到此异常:
org.springframework.http.converter.HttpMessageNotReadableException:JSON解析错误:无法构造“domain.Book”的实例(尽管至少存在一个创建者):没有要反序列化的int/Int参数构造函数/工厂方法来自数值 (81)
当我在 @ManyToOne
字段上使用 @JsonIgnore
时,其他数据保存得很好。
我认为问题出在我保存“章节”的方式上,但我不知道如何将其更改为正确的方式。
POST 的 JSON:
{
"name": "testBookName",
"chapters": [
{
"name": "testChapterName",
"number": 1
}
]
}
结果:
{
"id": 99,
"book": null,
"number": 1,
"name": "testChapterName",
"pages": null
}
第二个 JSON 变体:
{
"name": "testBookName",
"id": 99,
"chapters": [
{
"book": 99,
"name": "testChapterName",
"number": 1
}
]
}
结果:
JSON 解析错误:无法构造“domain.Book”的实例(尽管至少存在一个 Creator):没有用于从数值 (99) 反序列化的 int/Int 参数构造函数/工厂方法;嵌套异常是 com.fasterxml.jackson.databind.exc.MismatchedInputException:无法构造“domain.Book”的实例(尽管至少存在一个 Creator):没有从 Number 值(99 )\n 在 [来源:(PushbackInputStream);行:6,列:16](通过引用链:domain.Book[\"chapters\"]->java.util.ArrayList[0]->domain.Chapter[\"book\"])"
图书实体:
@Entity
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Book {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
private String author;
private String artist;
private String year;
private int views;
private double rating;
@Lob
private String image;
@Enumerated(EnumType.STRING)
private Status status;
@ElementCollection(targetClass = Genre.class, fetch = FetchType.EAGER)
@CollectionTable(name = "genres", joinColumns = @JoinColumn(name = "book_id"))
@Enumerated(EnumType.STRING)
private List<Genre> genres;
@OneToMany(mappedBy = "book", cascade = CascadeType.ALL, orphanRemoval = true)
private List<Chapter> chapters;
}
章节实体:
@Entity
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Chapter {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@ManyToOne
@JoinColumn(name = "book_id")
private Book book;
private int number;
private String name;
@OneToMany(targetEntity = Page.class, mappedBy = "chapter", cascade = CascadeType.ALL, orphanRemoval = true)
private List<Page> pages;
}
页面实体:
@Entity
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Page {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@ManyToOne
@JoinColumn(name = "chapter_id")
private Chapter chapter;
private int number;
@Lob
private String image;
}
POST Controller 方法:
@PostMapping()
public Chapter createChapter(@RequestBody Book book) {
List<Chapter> chapters = book.getChapters();
return chapterRepository.save(chapters.get(chapters.size() - 1));
}
}
最佳答案
此问题与您的第二个 JSON 变体有关
将您的 JSON 更改为这样就可以了。
{
"name": "testBookName",
"id": 99,
"chapters": [
{
"book": {
"id": 99
},
"name": "testChapterName",
"number": 1
}
]
}
关于java - 如何正确保存ManyToOne实体?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/60569697/