Spring Data JPA

You are a Spring Framework developer. The user wants to set up Spring Data JPA with repositories and entities to enable database persistence with minimal boilerplate code.

What to check first

• Verify spring-boot-starter-data-jpa is in your pom.xml or build.gradle
• Confirm database driver is included (e.g., h2, mysql-connector-java, postgresql)
• Check that application.properties or application.yml has spring.datasource.* and spring.jpa.hibernate.ddl-auto configured

Steps

1. Add Spring Data JPA dependency to pom.xml with version aligned to your Spring Boot version
2. Create an entity class annotated with @Entity and @Table(name="table_name")
3. Add @Id and @GeneratedValue(strategy=GenerationType.IDENTITY) annotations to the primary key field
4. Add @Column annotations to specify custom column names or constraints for fields
5. Create a repository interface extending JpaRepository<EntityType, IdType>
6. Configure spring.jpa.hibernate.ddl-auto=update in properties to auto-create/update schema
7. Inject the repository into your service or controller using @Autowired or constructor injection
8. Use repository methods like findAll(), findById(), save(), and create custom queries with @Query

Code

// User.java - Entity class
package com.example.entity;

import jakarta.persistence.*;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Entity
@Table(name = "users")
@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    @Column(name = "username", nullable = false, unique = true, length = 50)
    private String username;
    
    @Column(name = "email", nullable = false, unique = true)
    private String email;
    
    @Column(name = "age")
    private Integer age;
    
    @Column(name = "active", columnDefinition = "BOOLEAN DEFAULT true")
    private Boolean active;
}

// UserRepository.java - Repository interface
package com.example.repository;

import com.example.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;

import java.util.List;
import java.util.Optional;

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    
    Optional<User> findByUsername(String username);
    
    Optional<User> findByEmail(String

Note: this example was truncated in the source. See the GitHub repo for the latest full version.

Common Pitfalls

• Treating this skill as a one-shot solution — most workflows need iteration and verification
• Skipping the verification steps — you don't know it worked until you measure
• Applying this skill without understanding the underlying problem — read the related docs first

When NOT to Use This Skill

• When a simpler manual approach would take less than 10 minutes
• On critical production systems without testing in staging first
• When you don't have permission or authorization to make these changes

How to Verify It Worked

• Run the verification steps documented above
• Compare the output against your expected baseline
• Check logs for any warnings or errors — silent failures are the worst kind

Production Considerations

• Test in staging before deploying to production
• Have a rollback plan — every change should be reversible
• Monitor the affected systems for at least 24 hours after the change