错误：试图从空的一对一属性分配 id [com.dbtest.springboot.db_model.Family.user]

Question

告诉我如何正确地将一个由信息对象组成的集合添加到数据库中（一个表，例如一个家庭），以便这些对象引用用户表中的一个用户。此刻出现错误，尝试了不同的保存选项，错误依旧：

请求json：

[

{
"name":"luda",
"surname":"Petrova",
"phone":"2353636",
"bus":"black"
},
{
"name":"dima",
"surname":"Petrov",
"phone":"23536336",
"bus":"red"
},
{
"name":"ivan",
"surname":"Petrov",
"phone":"2353",
"bus":"blue"
}

]

休息控制器：

 @RequestMapping(value = { "fam/{id}" },method = RequestMethod.POST)
    public User addyfam (@PathVariable Long id, @RequestBody List<FamReq> fammreq){
        User usr = userRepo.findById(id).get();     
                var arr = new ArrayList<Family>();
        
        for(FamReq f : fammreq ) {
    
             arr.add(new Family( f.getName(),f.getSurname(),f.getPhone(),f.getBus()));
             
        }
                
        usr.setFamily(arr);
        
        userRepo.save(usr);     
        return usr;
    }

实体 1：

@Entity
@Table(name="usr")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    @Column(name="name")
    private String name;
    
    @Column(name="surname")
    private String surname;

    @OneToOne(
            mappedBy = "user",
            cascade = CascadeType.ALL,
            orphanRemoval = true,
            fetch = FetchType.LAZY
        )
    @JsonManagedReference
    private Passport passport;
    
    
    @OneToMany(
            mappedBy = "user",
            cascade = {CascadeType.ALL},
            orphanRemoval = true
        )
    private List<Family> family = new ArrayList<>();
 
  /**get/set and constr **/


}

实体 2：

@Entity
@Table(name="family")
public class Family {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    @Column(name="name")
    private String name;
    
    @Column(name="surname")
    private String surname;
    
    @Column(name="phone")
    private String phone;
    
    @Column(name="bus")
    private String bus;

    @ManyToOne(
            fetch = FetchType.LAZY
        )
    @MapsId
    @NotFound(action = NotFoundAction.IGNORE)
    private User user;
    
   /**get/set and constr **/
}

由于主键标识与外键相同，因此family表只包含副键，user表只包含主键。

更新：

    @RequestMapping(value = { "fam/{id}" },method = RequestMethod.POST)
    public User addyfam (@PathVariable Long id, @RequestBody List<FamReq> 
 fammreq){
    User us = userRepo.findById(id).get();
    
    var arr = new ArrayList<Family>();
    
    for(FamReq f : fammreq ) {
    
    Family savedFamily = famRepo.save(new Family(f.getName(),f.getSurname(),f.getPhone(),f.getBus()));
    
       arr.add(savedFamily);
    
    Family(f.getName(),f.getSurname(),f.getPhone(),f.getBus()));
   } 
    userRepo.save(arr);
    
    return us;
   }

如果从本质上讲，家庭表明了这一点：

@ManyToOne( cascade = CascadeType.ALL,
                fetch = FetchType.LAZY
            )
        @JoinColumn(name="user_id", referencedColumnName = "id")
        private User user;

错误：

ERROR: NULL in column "user_id" of relationship "family" violates NOT NULL constraint
   Details: The error line contains (sdgsgsgsegf, luda, 2353636, Petrova, null, null)

如果您指出：

@ManyToOne(
                fetch = FetchType.LAZY
            )
        @MapsId
        @NotFound(action = NotFoundAction.IGNORE)
        private User user;

然后

错误：

Error: attempted to assign id from null one-to-one property [com.dbtest.springboot.db_model.Family.user]

更新：

控制器当前正在使用中：

@RequestMapping(value = { "fam/{id}" },method = RequestMethod.POST)
        public User addyfam (@PathVariable Long id, @RequestBody List<FamReq> fammreq){
            User usr = userRepo.findById(id).get();     
                    var arr = new ArrayList<Family>();
            
            for(FamReq f : fammreq ) {
        
                 arr.add(new Family( f.getName(),f.getSurname(),f.getPhone(),f.getBus()));
                 
            }
                    
            usr.setFamily(arr);
            
            userRepo.save(usr);     
            return usr;
        }

回购：

@Repository
public interface UserRepo extends JpaRepository<User, Long >{
User findByname(String name);

void save(ArrayList<Family> fm);

}

完全错误：

Hibernate: insert into family (bus, name, phone, surname, user_id) values (?, ?, ?, ?, ?)
Hibernate: insert into family (bus, name, phone, surname, user_id) values (?, ?, ?, ?, ?)
Hibernate: insert into family (bus, name, phone, surname, user_id) values (?, ?, ?, ?, ?)
2021-11-14 23:31:06.693 ERROR 13192 --- [nio-9091-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.beans.NotReadablePropertyException: Invalid property 'id' of bean class [java.util.ArrayList]: Could not find field for property during fallback access!] with root cause

org.springframework.beans.NotReadablePropertyException: Invalid property 'id' of bean class [java.util.ArrayList]: Could not find field for property during fallback access!
at org.springframework.data.util.DirectFieldAccessFallbackBeanWrapper.getPropertyValue(DirectFieldAccessFallbackBeanWrapper.java:58) ~[spring-data-commons-2.5.6.jar:2.5.6]
at org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformation.getId(JpaMetamodelEntityInformation.java:162) ~[spring-data-jpa-2.5.6.jar:2.5.6]
at org.springframework.data.repository.core.support.AbstractEntityInformation.isNew(AbstractEntityInformation.java:46) ~[spring-data-commons-2.5.6.jar:2.5.6]
at org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformation.isNew(JpaMetamodelEntityInformation.java:246) ~[spring-data-jpa-2.5.6.jar:2.5.6]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:596) ~[spring-data-jpa-2.5.6.jar:2.5.6]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]

Answer 1

这里的问题是您尝试通过Id 建立关系，但new Family( f.getName(),f.getSurname(),f.getPhone(),f.getBus()) 没有为您的Family 分配任何Id。

1. 创建族对象并将其存储到变量中。
2. 在.save(familyObject) 的帮助下拯救您的家人，然后您的家人才会被分配一个Id。
3. 保存您的User，并附上一个家人。

您的控制器应如下所示：

        for (FamReq f : fammreq ) {
             Family savedFamily = familyRepo.save(new Family(f.getName(),f.getSurname(),f.getPhone(),f.getBus(), us.getId()));
             arr.add(savedFamily);
        }
        us.setFamily(arr);wq21`
        userRepo.save(us);

你也应该有一个FamilyRepository，像这样：

@Repository
public interface FamilyRepo extends JpaRepository<Family, Long>{
    
}

注意：不要忘记在控制器中创建此类的注入。

注意：切勿覆盖存储库中的 .save() 方法。

另外，您必须确保 id 找到您的用户，否则会抛出将被 Global Controller Advice 捕获的异常。因为如果您不这样做，您的 JPA 将在引用 NULL 值时尝试创建关系。