我正在建立两个实体“事件”和“消息”之间的一对多关系。 事件是父级，消息是子级。 每当我试图向“message”中插入一行数据时，我总是得到java.sql.SQLINTEGRITYConstraintViolationException:列'msg'不能为null，这当然是我输入的。 当我将msg属性设置为可空时，错误消息将变为java.sql.SQLintegrityConstraintViolationException:列'USER_NAME'不能为空。 看来mysql并没有从邮递员那里得到任何争论。 我一整天都在寻找答案，但是找不到答案，请帮帮我。 下面是代码。

事件实体

package com.example.springsecurityjwt.models;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.persistence.*;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name ="Event")
public class Event {

    @Id
    private int eventId;
    private int mountainId;
    private String event_name;
    private String leader;
    private Date date;
    private int eventType;
    private int minNumOfMember;
    private int numOfMember;
    private String description;
    @Column(columnDefinition = "integer default 0")
    private int status;

    @OneToMany
    @JoinColumn(name = "eventId", referencedColumnName = "eventId")
    List<Message> messages = new ArrayList<>();

}

消息实体

package com.example.springsecurityjwt.models;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import java.util.Date;

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name ="Message")
public class Message {

    @Id
    private int messageId;
    private int eventId;
    private String userName;
    private String msg;
    private Date date;

}

信息服务

@Service
public class MessageService {

    @Autowired
    private MessageRepository messageRepository;

    public Message addMessage(Message message){
       return messageRepository.save(message);

    }
}

MessageController

@RestController
@RequestMapping("/message")
public class MessageController {

    @Autowired
    private MessageService messageService;

    @PostMapping("/add")
    public Message addMessage(@Validated Message message){
        return messageService.addMessage(message);
    }
}

依赖关系

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>spring-security-jwt</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-security-jwt</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>11</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt-api</artifactId>
            <version>0.11.2</version>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt-impl</artifactId>
            <version>0.11.2</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt-jackson</artifactId> <!-- or jjwt-gson if Gson is preferred -->
            <version>0.11.2</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
            <version>2.0.1.Final</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

mysql中的消息表在此处输入图像描述

错误消息

Hibernate: insert into message (date, event_id, msg, user_name, message_id) values (?, ?, ?, ?, ?)
2020-06-28 20:25:37.125  WARN 16204 --- [nio-8080-exec-2] o.h.engine.jdbc.spi.SqlExceptionHelper   : SQL Error: 1048, SQLState: 23000
2020-06-28 20:25:37.125 ERROR 16204 --- [nio-8080-exec-2] o.h.engine.jdbc.spi.SqlExceptionHelper   : Column 'msg' cannot be null
2020-06-28 20:25:37.140 ERROR 16204 --- [nio-8080-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.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement] with root cause

java.sql.SQLIntegrityConstraintViolationException: Column 'msg' cannot be null
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:117) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:953) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1092) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1040) ~[mysql-connector-java-8.0.20.jar:8.0.20]