Question

我有这些表格：

CREATE TABLE ref.doc (
    id       serial PRIMARY KEY,
    iddoc    integer NOT NULL UNIQUE,
    docname  varchar(254) NOT NULL
);

CREATE TABLE person (
    id       serial PRIMARY KEY,
    name     varchar(40) DEFAULT NULL, 
    doctype  integer DEFAULT NULL REFERENCES ref.doc(iddoc)
);

我需要使用Spring构建一个RESTful Web服务，它接收JSON并在经过一些验证后将它们保存到数据库中。例如，iddoc = 2中有ref.doc的记录。所以person的JSON看起来像这样：

{
    "name": "John",
    "doctype": 2
}

我想做这样的事情：

@RestController
public class PersonController {

    @Autowired
    PersonRepository personRepository;

    @Transactional
    @RequestMapping(value = "/add", method = RequestMethod.POST)
    @ResponseBody
    public Person add(@RequestBody Person person) {
        // some logic
        personRepository.saveAndFlush(person);
        return person;
    }
}

我有这些实体：

@Entity
@Table(schema = "ref")
public class Doc {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @JsonIgnore
    private long id;

    private Integer iddoc;
    private String docname;

    ...
}

@Entity
public class Person {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @JsonIgnore
    private long id;

    private String name;

    @ManyToOne
    @JoinColumn(name = "doctype", referencedColumnName = "iddoc", nullable = false)
    private Doc doc;

    ...
}

在这种情况下，doc中的person始终是null，而且它几乎可以理解。但是如何实现我需要的行为？

Answer 1

你看过这个链接吗？

http://www.javaworld.com/article/2077819/java-se/understanding-jpa-part-2-relationships-the-jpa-way.html

特别要看一下订单表和客户表之间的关系。

根据我的理解，你需要一个人拥有多份文件。所以尝试更改定义

private Doc doc;

到

@OneToMany(mappedBy="person", fetch=FetchType.EAGER)
   private List<Doc> docs;

并在Doc类中尝试添加：

 @ManyToOne(optional=false)
 @JoinColumn(name="doctype",referencedColumnName="iddoc")
   private Person person;

这应该是实现所需行为的正确方法，而不是100％确定。这是另一个链接，解释了如何实现所需的解决方案：

https://en.wikibooks.org/wiki/Java_Persistence/OneToMany

Answer 2

        @RestController
        public class PersonController {

            @Autowired
            PersonRepository personRepository;

            @Autowired
            DocRepository docRepository;

            @Transactional
            @RequestMapping("/add")
            @ResponseBody
            public void add(@RequestBody Person person) {
                Doc doc=docRepository.findByIddoc(person.getDoc().getIddoc());
                if(!(doc==null)){
                Person personAdd=new Person();
                personAdd.setName("name");
                personAdd.setDoc(doc);
                personRepository.saveAndFlush(person);
                }
            }
        }



    @Entity
    public class Person {

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @JsonIgnore
        private long id;

        private String name;

        @ManyToOne(cascade=CascadeType.ALL)
        @JoinColumn(name = "doctype", referencedColumnName = "iddoc", nullable = false)
        private Doc doc;






@Entity
@Table(schema = "demo")
public class Doc {

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

    private Integer iddoc;
    private String docname;

在RESTful Web服务中使用@JoinColumn接收Spring的实体

2 个答案: