Question

我在Spring Boot（带有Postgresql DB）应用程序中在两个模型（car_model和car_picture_model）之间建立了OneToOne（单向）关系。从Java代码启动并插入数据后，我可以获得正确的关系信息：

id | make    | car_image_id
 1 | Ferrari |            2

我可以选择所有汽车和所有图像。 DBeaver同时显示表和关系箭头。

但是在日志中，我可以看到异常：

org.hibernate.tool.schema.spi.CommandAcceptanceException：通过JDBC语句执行DDL错误在org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept（GenerationTargetToDatabase.java:67）〜[hibernate-core-5.2.17.Final.jar：5.2.17.Final] ... 在java.lang.Thread.run（Thread.java:748）〜[na：1.8.0_181] 引起原因：org.postgresql.util.PSQLException：错误：关系“ car_model”不存在在org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse（QueryExecutorImpl.java:2182）〜[postgresql-9.4-1206-jdbc42.jar：9.4]

完整日志：https://pastebin.com/ui1Cj99j
删除名称=“ cars”不会更改任何内容。
与使用car_name添加@Table注释相同

CarModel：

import javax.persistence.*;

@Entity(name = "cars")
public class CarModel {

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

    @Column
    private String make;

    @OneToOne
    @JoinColumn(name = "car_image_id", unique = true)
    private CarPictureModel carPictureModel;

// Getters and Setters

}

CarPictureModel：

import javax.persistence.*;

@Entity
public class CarPictureModel {

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

    @Column
    private String fileName;

    @Column
    private String fileType;

    @Lob
    @Column
    private byte[] data;

//    for (bidirectional mapping)
//    @OneToOne(mappedBy = "carPictureModel")
//    private CarModel carModel;

// Getters and Setters

}

在application.properties中有两个：

spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect
spring.jpa.hibernate.ddl-auto=create-drop

您能帮我一下，告诉我我在这里想念什么吗？

Answer 1

似乎您缺少@Table批注。如果您的表名是car_model，请在类定义之前使用@Table（name =“ car_model”）。

与CarPictureModel相同。

@Entity(name = "cars") @Table(name = "car_model") public class CarModel { }

@Entity @Table(name = "car_picture_model") public class CarPictureModel { }

Answer 2

@Rohit gave me a good hint.
I chaned spring.jpa.hibernate.ddl-auto=create-drop to spring.jpa.hibernate.ddl-auto=create and the problem is gone. Now i got in logs:

Hibernate: alter table car_model drop constraint FKjlrfjf7bhyha1pkb0004q6l6w
Hibernate: drop table if exists car_model cascade
Hibernate: drop table if exists car_picture_model cascade
Hibernate: drop sequence if exists hibernate_sequence
Hibernate: create sequence hibernate_sequence start 1 increment 1
Hibernate: create table car_model (id int4 not null, color varchar(255), make varchar(255), mfy int4, model varchar(255), car_image_id int4, primary key (id))
Hibernate: create table car_picture_model (id int4 not null, data oid, file_name varchar(255), file_type varchar(255), primary key (id))

So it looks like both create and create-drop first drops all tables before creating new one. When the problem occurred there were no tables to drop because create-drop droped earlier all tables when stopping server with ctrl-c. As this logs shows:

SchemaDropperImpl$DelayedDropActionImpl : HHH000477: Starting delayed drop of schema as part of SessionFactory shut-down'
Hibernate: alter table car_model drop constraint FKjlrfjf7bhyha1pkb0004q6l6w
Hibernate: drop table if exists car_model cascade
Hibernate: drop table if exists car_picture_model cascade
Hibernate: drop sequence if exists hibernate_sequence

关系OneToOne的PSQLException：关系“ car_model”不存在

2 个答案: