7

I have two entities: Comment, and SubComment. A Comment can have multiple SubComments. I'm trying to establish a one to many/many to one bidirectional relationship with Hibernate.

I do not know what is wrong. Both of the tables seem to have been created correctly in PSQL.

Comment.java

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

@Entity
public class Comment {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @Column
    private String text;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "comment")
    private Set<SubComment> subComment;

    public long getId() {
        return id;
    }

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

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }
}

SubComment.java

import javax.persistence.*;

@Entity
public class SubComment {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    private String text;

    @ManyToOne
    private Comment comment;

    public long getId() {
        return id;
    }

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

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    public Comment getComment() {
        return comment;
    }

    public void setComment(Comment comment) {
        this.comment = comment;
    }
}

I'm getting this error:

Error executing DDL via JDBC StatementCaused by: org.postgresql.util.PSQLException: ERROR: relation "sub_comment" does not exist

Hibernate: create table "user" (id  bigserial not null, email varchar(255), name varchar(255), username varchar(255), primary key (id))
Hibernate: create table comment (comment_id  bigserial not null, text varchar(255), primary key (comment_id))
Hibernate: create table sub_comment (sub_comment_id  bigserial not null, text varchar(255), comment_comment_id int8, primary key (sub_comment_id))
Hibernate: alter table sub_comment add constraint FK87789n34vmns9eeyw6jgc5ghp foreign key (comment_comment_id) references comment

application.properties

spring.jpa.hibernate.ddl-auto=create-drop
spring.datasource.url=jdbc:postgresql://localhost:5432/dbname
spring.datasource.data-username=username
spring.datasource.driver-class-name=org.postgresql.Driver

spring.jpa.show-sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect
spring.jpa.database-platform=org.hibernate.dialect.PostgreSQL9Dialect
spring.jpa.properties.hibernate.temp.use_jdbc_metadata_defaults = false
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4
  • Post your entire logtrace. Commented May 9, 2018 at 8:15
  • did your problem got solved? Commented May 10, 2018 at 7:33
  • post you DAO classes and service classes in the question. Commented May 10, 2018 at 7:35
  • You have an answer to accept. Commented Jul 27, 2018 at 17:24

4 Answers 4

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4

You missed @JoinColumn. You will get another error due to field based access. Use Property based access instead:

import javax.persistence.*;

@Entity
@Table(name = "subcomment")
public class SubComment implements Serializable {

    private static final long serialVersionUID = -3009157732242241606L;

    private long id;
    private String text;
    private Comment comment;

    @Id
    @Column(name = "sub_id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    public long getId() {
        return id;
    }

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

    @Basic
    @Column(name = "sub_text")
    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    @ManyToOne
    @JoinColumn(name = "sub_fk_c_id", referencedColumnName = "c_id") // here the exact field name of your comment id in your DB
    public Comment getComment() {
        return comment;
    }

    public void setComment(Comment comment) {
        this.comment = comment;
    }
}

Also make changes here too:

import javax.persistence.*;

@Entity
@Table(name = "comment")
public class Comment implements Serializable {

    private static final long serialVersionUID = -3009157732242241606L;    

    private long id;
    private String text;
    private Set<SubComment> subComment = new HashSet<>();

    @OneToMany(mappedBy = "comment", targetEntity = SubComment.class)
    public Set<SubComment> getSubComment() {
        return subComment;
    }

    public void setSubComment(Set<SubComment> subComment) {
        this.subComment = subComment;
    }

    @Id
    @Column(name = "c_id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    public long getId() {
        return id;
    }

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

    @Basic
    @Column(name = "c_text")
    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }
}

Paste the following in your application.properties file:

spring.jpa.properties.hibernate.id.new_generator_mappings = false
spring.jpa.properties.hibernate.format_sql = true
logging.level.org.hibernate.SQL=DEBUG
logging.level.org.hibernate.type.descriptor.sql.BasicBinder=TRACE
spring.jpa.hibernate.ddl-auto=create

In your pom.xml file paste these:

    <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <scope>runtime</scope>
    </dependency>

For further reference see this stackoverflow post.

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6 Comments

Tried your fixes (copy and pasted), same result... org.postgresql.util.PSQLException: ERROR: relation "sub_comment" does not exist
Added another edit. It should surely work by drop your existing tables and create new ones.
If the solution works, then do accept the answer as solution and upvote it.
Same result, sub_comment does not exist. Why would I get an error due to field based access. When do you use field based vs property based?
add your application.properties file contents to your question.
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1

I know that this answer is late but maybe it will help someone, their problem is that they have not configured the schema, which is why they are throwing that error.

Here is how to configure the schema in postgresql:

spring.jpa.properties.hibernate.default_schema = "his schema"
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0

Many sub comments have belonged to one comment and model should look like that (comment_id you can generate e.g UUID.randomUUID().toString() )

@Entity
@Table(name = "comment")
public class Comment{

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

@Column(name = "comment_id")
String commentId;

}

@Entity
@Table(name = "sub_comment")
public class SubComment{

...
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "comment_id", referencedColumnName = "comment_id")
Comment comment;
...
}

If You use e.g liquidbase to control your data source :

  - changeSet:
      id: 1
      author: author.name
      changes:
      - addForeignKeyConstraint:
          baseColumnNames: comment_id
          baseTableName: sub_comment
          constraintName: fk_comment_subcomment
          referencedColumnNames: comment_id
          referencedTableName: comment
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7 Comments

i would ask you to see this stackoverflow solution stackoverflow.com/a/44055520/7538821
What have your link in common to question? If you mean that I miss getter/setter nowadays Lombok deals with this and I present only a general solution, not whole implementation.
If you do a field based property access with many to one annotation then the project won't even compile and this bug is still in hibernate 5. Property based access is the only solution.
You can refer here thoughts-on-java.org/…
Unfortunately, you are wrong. I do not know what Hibernate magic does under the hood but join column name can have a name which exists in DB. This is the piece of my code which works on real env.
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0

Had a similar problem and my issue was that I was missing referencedColumnName under my SubCategory class.

Had this

  @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.MERGE)
    @JoinColumn(name = "category_id, nullable = false)
    private Category category;

Instead of

@ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.MERGE)
    @JoinColumn(name = "category_id", referencedColumnName = "id", nullable = false)
    private Category category;

so my subcategory table was not being created.

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