在 JPA 中使用 oneToMany 关系时，Postgresql 在列中抛出空值违反非空约束

Question

我尝试测试 Hibernate 的一对多关系。我定义 Post 和 PostComment 实体如下： Post.java

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

@Entity
@Table(name = "post")
public class Post {

    @Id
    @Column(name="post_id")
    @GeneratedValue(strategy= GenerationType.IDENTITY)
    private Long postId;

    @Column(name="title")
    private String title;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "post",
            orphanRemoval = true)
    private List<PostComment> comments = new ArrayList<>();

    public Post() {};

    public Post(String title) {
        this.title = title;
    }
   // Add getter and setter
}

发表评论.java

    import javax.persistence.*;

@Entity
@Table(name = "post_comment")
public class PostComment {
    @Id
    @Column(name="comment_id")
    @GeneratedValue(strategy= GenerationType.IDENTITY)
    private Long commentId;

    @Column(name="review")
    private String review;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "post_id")
    private Post post;

    public PostComment() {};
    public PostComment(String review) {
        this.review = review;
    }
    // Add getter and setter
}

PostRepository.java

public interface PostRepository extends JpaRepository<Post,Long> {
}

和db-changelog.xml

<changeSet id="1" author="dev">
    <createTable tableName="post_comment">
        <column name="comment_id" type = "bigint">
            <constraints nullable="false" primaryKey="true"></constraints>
        </column>
        <column name="review" type="varchar(255)"></column>
    </createTable>
    <createTable tableName="post">
        <column name="post_id" type="bigint">
            <constraints nullable="false" primaryKey="true"></constraints>
        </column>
        <column name="title" type = "varchar(255)"></column>
    </createTable>
</changeSet>

然后，我使用 SpringJUnit 添加一个新帖子，如 PostServiceITTest.java 中所示

 import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.SpringApplicationConfiguration;
import org.springframework.test.annotation.DirtiesContext;
import org.springframework.test.context.ActiveProfiles;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.web.WebAppConfiguration;

import java.util.Arrays;

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = {Application.class})
@WebAppConfiguration
@DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_CLASS)
@ActiveProfiles("devmock")
public class PostServiceITTest {
    @Autowired
    private PostRepository postRepository;

    @Test
    public void testAddPost(){
        Post post = new Post(" Post 1");

        PostComment postComment1 = new PostComment(" Post comment 1");  
        PostComment postComment2 = new PostComment(" Post comment 2");
        post.setComments(Arrays.asList(postComment1,postComment2));

        postRepository.save(post);
    }
}

不幸的是，测试抛出了与空违反约束相关的 Postgresql 错误：

    Caused by: org.postgresql.util.PSQLException: ERROR: null value in column "post_id" violates not-null constraint
  Detail: Failing row contains (null,  Post 1).

我非常感谢您的宝贵时间。

Answer 1

您似乎没有传递 的值post_id。