Spring JPA error on DB column returns error related to column name

Question

I receive an error when trying to query a Postgres DB using JPA.

Student.java:

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Student {
    @Id
    @GeneratedValue
    private Long id;
    private String name;
    private String passportNumber;

    public Student() {
        super();
    }

    public Student(Long id, String name, String passportNumber) {
        super();
        this.id = id;
        this.name = name;
        this.passportNumber = passportNumber;
    }
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getPassportNumber() {
        return passportNumber;
    }
    public void setPassportNumber(String passportNumber) {
        this.passportNumber = passportNumber;
    }

}

appliction.properties:

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.PostgreSQLDialect

spring.jpa.hibernate.ddl-auto=none

spring.jpa.hibernate.show-sql=true

spring.datasource.url=jdbc:postgresql://localhost:5432/shorten-db

spring.datasource.username=my_user

spring.datasource.password=my_password

spring.datasource.initialization-mode=always

spring.datasource.initialize=true

spring.datasource.schema=classpath:/schema.sql

spring.datasource.continue-on-error=true

appliction.yml:

spring:
  datasource:
    url: jdbc:postgresql://localhost:5432/shorten-db
    username: my_user
    password: my_password
    driverClassName: org.postgresql.Driver

 spring.datasource.schema=classpath:/schema.sql

refers to this schema:

DROP TABLE student;

CREATE TABLE student

(

 id varchar(100) NOT NULL,

 name varchar(100) DEFAULT NULL,

 passportNumber varchar(100) DEFAULT NULL,

 PRIMARY KEY (id)

);

When I invoke the service "/students" :

@PostMapping("/students")
public ResponseEntity<Object> createStudent(@RequestBody Student student) {
    Student savedStudent = studentRepository.save(student);

    URI location = ServletUriComponentsBuilder.fromCurrentRequest().path("/{id}")
            .buildAndExpand(savedStudent.getId()).toUri();

    return ResponseEntity.created(location).build();

}

I receive the following error:

postgres-db    | 2020-08-28 21:46:28.108 UTC [257] HINT:  Perhaps you meant to reference the column "student0_.passportnumber".
postgres-db    | 2020-08-28 21:46:28.108 UTC [257] STATEMENT:  select student0_.id as id1_1_, student0_.name as name2_1_, student0_.passport_number as passport3_1_ from student student0_

How to implement the hint specified in the message Perhaps you meant to reference the column "student0_.passportnumber" I'm not explicitly specifying the SQL and trying to use JPA only. Do I need a custom query or should I modify the student entity ?

Avinash Sagar · Accepted Answer · 2020-08-28 22:34:52Z

4

JPA expects column names in the form of lower case and each word separated by an underscore. This translates to a camel cased java variable names. In your case, you have java variable name as passportNumber which translates to passport_number. There are three ways this can be solved:

Rename java variable to passportnumber, meaning its a single word. Unfortunately, it doesn't look so good since it breaks the variable naming convention of java.
Rename table column to passport_number, hence making correct JPA connection.
Annotate your java variable with @Column(name="passportNumber").

answered Aug 28, 2020 at 22:34

Avinash Sagar

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