弹簧引导ManyToOne关系

Question 1

我正尝试使用冲刺启动ManyToOne注释上的一个领域。我的代码看起来像这样用的 Order 类

package com.example.demo_app.data.models;

import javax.persistence.*;

@Entity
public class Order extends Object {
    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "person_id")
    private Person person;

    public Person getPerson() {
        return person;
    }

    public void setPerson(Person person) {
        this.person = person;
    }
}

和 Person 类看起来像这样

package com.example.demo_app.data.models;

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

@Entity
public class Person {
    private Long id;

    @OneToMany(targetEntity = Order.class)
    private List<Order> orders;

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

    @Id
    @GeneratedValue
    public Long getId() {
        return id;
    }

    public List<Order> getOrders() {
        return orders;
    }

    public void setOrders(List<Order> orders) {
        this.orders = orders;
    }
}

这是错误的，我得到

Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Could not determine type for: java.util.List, at table: person, for columns: [org.hibernate.mapping.Column(orders)]

Caused by: org.hibernate.MappingException: Could not determine type for: java.util.List, at table: person, for columns: [org.hibernate.mapping.Column(orders)]
    at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:512)

任何帮助表示赞赏。谢谢！

Question 2

你得到错误的，因为 ORDER 是SQL关键词。试着改变表名称的类 Order 到别的东西

@Entity
@Table(name="ORDERS")
public class Order {

@Id
private Long id;

@ManyToOne
@JoinColumn(name = "person_id")
private Person person;

//getters and setters

}

编辑：这是 Person 类，把注释 @Id 和 @GeneratedValue 在id领域，不在吸气。

@Entity
@Table(name = "PERSON")
public class Person {
  @Id
  @GeneratedValue
  private Long id;

  @OneToMany(targetEntity = Order.class)
  private List<Order> orders;

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

  public Long getId() {
      return id;
  }

  public List<Order> getOrders() {
      return orders;
  }

  public void setOrders(List<Order> orders) {
      this.orders = orders;
  }
}

Grobocop12 · Answer 1 · 2021-11-22T14:48:28

你得到错误的，因为 ORDER 是SQL关键词。试着改变表名称的类 Order 到别的东西

@Entity
@Table(name="ORDERS")
public class Order {

@Id
private Long id;

@ManyToOne
@JoinColumn(name = "person_id")
private Person person;

//getters and setters

}

编辑：这是 Person 类，把注释 @Id 和 @GeneratedValue 在id领域，不在吸气。

@Entity
@Table(name = "PERSON")
public class Person {
  @Id
  @GeneratedValue
  private Long id;

  @OneToMany(targetEntity = Order.class)
  private List<Order> orders;

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

  public Long getId() {
      return id;
  }

  public List<Order> getOrders() {
      return orders;
  }

  public void setOrders(List<Order> orders) {
      this.orders = orders;
  }
}

谢谢你的建议。不幸的是，这并没有解决。我仍然具有同样的问题。
也许是尝试把 spring.jpa.show-sql=true 在你的属性文件。它可以帮助你确定问题。

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