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我试图弄清楚如何查找和返回与特定作者姓名关联的所有书籍。

{
    "bookId": 5,
    "bookName": "test2",
    "publishYear": 2022,
    "publisher": "test2",
    "authors": [
        {
            "id": 5,
            "name": "Heny",
            "surname": "Blakc"
        },
        {
            "id": 6,
            "name": "Garyy",
            "surname": "Harrys"
        }
    ]
}

我想归还 Garyy 为作者的所有书籍。

我正在使用 Spring Boot + Postgres SQL OneToMany 注释。

将不胜感激任何建议。

作者控制器：

package com.example.demo.controller;


import com.example.demo.entity.AuthorEntity;
import com.example.demo.repository.AuthorRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/author")
public class AuthorController {
    @Autowired
    AuthorRepository authorRepository;

    @GetMapping("/all")
    public List<AuthorEntity> author(){
        return authorRepository.findAll();
    }
    @PostMapping("/create")
    public AuthorEntity createAuthor(@RequestBody AuthorEntity author){
        AuthorEntity savedAuthor = authorRepository.save(author);
        return savedAuthor;
    }
    @GetMapping("/find/{author}")
    public List<AuthorEntity> findAuthor(@PathVariable(value = "author") String name){
        return authorRepository.findByName(name);
    }

}

图书控制器：

package com.example.demo.controller;


import com.example.demo.entity.BookEntity;
import com.example.demo.repository.BookRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;


@RestController
@RequestMapping("/book")
public class BookController {


    @Autowired
    private BookRepository bookRepository;




    @GetMapping("/all")
    public List<BookEntity> getAllBooks(){
        List<BookEntity> allBookList = bookRepository.findAll();

        return allBookList;
    }

    @GetMapping("/findBook/{name}")
    public List<BookEntity> getBookByName(@PathVariable(value = "name")String bookName)
    {
        return bookRepository.findByBookName(bookName);
    }

    @GetMapping("/year/{year}")
    public List<BookEntity> getBookByYear(@PathVariable(value = "year")Integer year)
    {
        return bookRepository.findByPublishYear(year);
    }
    @GetMapping("/publisher/{publisher}")
    public List<BookEntity> getBookByPublisher(@PathVariable(value = "publisher")String publisher)
    {
        return bookRepository.findByPublisher(publisher);
    }

    @PostMapping("/create-book")
    public BookEntity createBook (@RequestBody BookEntity book){
        BookEntity savedBook = bookRepository.save(book);

        return savedBook;
    }


}

作者实体：

package com.example.demo.entity;

import javax.persistence.*;

@Entity
@Table(name = "authors")
public class AuthorEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "name", nullable = false)
    private String name;
    @Column(name = "surname",nullable = false)
    private String surname;

    @ManyToOne(fetch =FetchType.LAZY)
    private BookEntity books;



    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSurname() {
        return surname;
    }

    public void setSurname(String surname) {
        this.surname = surname;
    }

    @Override
    public String toString() {
        return "AuthorEntity{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", surname='" + surname + '\'' +
                ", books=" + books +
                '}';
    }

}

图书实体：

package com.example.demo.entity;

import javax.persistence.*;
import java.util.List;

@Entity
@Table(name = "books")
public class BookEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)

    private Integer bookId;

    @Column(name = "book_name", nullable = false)
    private String bookName;

    @Column(name = "publish_year",nullable = false)
    private Integer publishYear;

    @Column(name = "publisher",nullable = false)
    private String publisher;

    @OneToMany(targetEntity = AuthorEntity.class, cascade = CascadeType.ALL)
    private List<AuthorEntity> authors;


    public List<AuthorEntity> getAuthors() {
        return authors;
    }

    public void setAuthors(List<AuthorEntity> authors) {
        this.authors = authors;
    }

    public Integer getBookId() {
        return bookId;
    }

    public void setBookId(Integer bookId) {
        this.bookId = bookId;
    }

    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    public Integer getPublishYear() {
        return publishYear;
    }

    public void setPublishYear(Integer publishYear) {
        this.publishYear = publishYear;
    }

    public String getPublisher() {
        return publisher;
    }

    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }

    @Override
    public String toString() {
        return "BookEntity{" +
                "bookId=" + bookId +
                ", bookName='" + bookName + '\'' +
                ", publishYear=" + publishYear +
                ", publisher='" + publisher + '\'' +
                ", authors=" + authors +
                '}';
    }
}

作者库：

package com.example.demo.repository;

import com.example.demo.entity.AuthorEntity;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.List;

public interface AuthorRepository extends JpaRepository<AuthorEntity, Integer> {
    List<AuthorEntity> findByName(String name);
}

书库：

package com.example.demo.repository;

import com.example.demo.entity.BookEntity;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.List;

public interface BookRepository extends JpaRepository<BookEntity, Integer> {
    public List<BookEntity> findByBookName(String bookName);
    public List<BookEntity> findByPublishYear(Integer year);
    public List<BookEntity> findByPublisher(String publisher);
}
4

2 回答 2

1

有多种方法可以做到这一点，一种方法是forEach and filter 在java本身中使用

 List<BookeEntity> books = getBooks();
 books.forEach(e->{
        List<AuthorEntity> al= e.getAuthors().stream().filter(ee->ee.getName().equals("Garyy")).collect(Collectors.toList());
        e.setAuthors(al);
    });
于 2020-11-15T14:07:05.257 回答
0

你的数据库设计是错误的。现实：

  • 1位作者写了一本书或多本书，
  • 由一位或多位作者撰写的 1 本书。

因此，您需要一个表作者书来将关系多对多转换为 2 个关系：一对多、多对一。

您可以查看https://www.stat.auckland.ac.nz/~paul/ItDT/HTML/node42.html部分5.6.3.2 关系

于 2020-11-15T15:47:12.233 回答