How to Resolve org.hibernate.MappingException in Spring Boot for SingleTableEntityPersister

What causes the org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister in Spring Boot?

// Example of a Spring Boot entity class with potential issues
@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    public User() {} // Default constructor

    // Getters and setters
}

The org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister typically arises in a Spring Boot application using Hibernate ORM when there are issues mapping entities to database tables. This error signals that Hibernate could not locate a suitable constructor for the entity, affecting persistence operations.

// Example of correctly structuring an entity
@Entity
@Table(name = "product")
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String title;

    // Default no-argument constructor
    public Product() {}

    // Getters and setters
}

Causes

• Missing a default no-argument constructor in the entity class.
• Incorrectly defined entity mappings or annotations.
• Invalid primary key configuration.
• Entities not correctly registered in the Spring context.

Solutions

• Ensure that each entity class has a public no-argument constructor.
• Verify that mappings and annotations correspond to the database schema.
• Check that primary key fields are correctly annotated with @Id and @GeneratedValue.
• Scan for entity classes in the Spring Boot application context.

Mistake: Forgetting to add a default constructor in your entity class.

Solution: Always include a public no-argument constructor.

Mistake: Incorrectly annotating primary key fields.

Solution: Ensure proper use of @Id and @GeneratedValue annotations.

Mistake: Not scanning for entity classes in the application context.

Solution: Check your @EntityScan configuration.