无法使用 Spring-Boot & Spring-JPA 保存 "Many"-@OneToMany 的实体

Question

我正在使用 Spring 引导和 MySQL。我按照 this link 设置了所有内容，并且能够连接到 MySql 和 read/write 数据。但是存在 1:n 关系，我无法保存多方实体：

    @Entity
    public class OneSideOfRelationship {
      @Id
      @GeneratedValue(strategy = GenerationType.AUTO)
      private long oneId;
      private String someText;
      @OneToMany(mappedBy="oneId")
      private List<ManySideOfRelationship> manySide;

      [Constructor / Getter / Setter]
    }

    @Entity
    public class ManySideOfRelationship {
      @Id
      @GeneratedValue(strategy = GenerationType.AUTO)
      private long manyId;
      @ManyToOne(targetEntity=OneSideOfRelationship.class)
      @JoinColumn
      private long oneId;
      private String someMoreText;

      [Constructor / Getter / Setter]
    }

    @Transactional
    public interface OneDao extends CrudRepository<OneSideOfRelationship, Long> {}

    @Transactional
    public interface ManyDao extends CrudRepository<ManySideOfRelationship, Long> {}

如果我在我的控制器中这样做：

    [...]
    @Autowired
    @private ManySideOfRelationship manyDao;
    [...]
      ManySideOfRelationship many = new ManySideOfRelationship();
      many.setOneId(1L);
      many.setSomeMoreText("Text");
      manyDao.save(many);
    [...]

我得到了：

    org.springframework.orm.jpa.JpaSystemException: could not get a field value by reflection getter of com.package.database.OneSideOfRelationship.oneId; nested exception is org.hibernate.PropertyAccessException: could not get a field value by reflection getter of com.package.database.OneSideOfRelationship.oneId

出于我的 application.properties:

    spring.datasource.url = jdbc:mysql://myurl:myport/mydatabase
    spring.datasource.username = myusername
    spring.datasource.password = mypassword
    spring.jpa.hibernate.ddl-auto = update
    spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy
    spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

还有一些来自 pom.xml

的东西

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
    </dependency>

希望有人有想法。

Answer 1

oneId 必须是 OneSideOfRelationship 的数据类型，不长。

  @ManyToOne(targetEntity=OneSideOfRelationship.class)
  @JoinColumn
  private OneSideOfRelationship oneId;