JPA Entity Generation

Name: backend-entity
Rating: 92
Author: sliard

Generate JPA entities following project conventions for Spring Boot 3.4.x with Java 21 and PostgreSQL 16.

Required Structure

java

@Entity
@Table(name = "table_names")
@EntityListeners(AuditingEntityListener.class)
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class EntityName {

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

    // Business fields here

    @CreatedDate
    @Column(nullable = false, updatable = false)
    private Instant createdAt;

    @LastModifiedDate
    @Column(nullable = false)
    private Instant updatedAt;
}

Naming Conventions

•Class name: PascalCase singular (Product, User, OrderItem)
•Table name: snake_case plural (products, users, order_items)
•Column names: snake_case (created_at, first_name)

Required Elements

•ID: Always use UUID with @GeneratedValue(strategy = GenerationType.UUID)
•Timestamps: Always include createdAt (non-updatable) and updatedAt
•Auditing: Use @EntityListeners(AuditingEntityListener.class)
•Lombok: Use @Data, @Builder, @NoArgsConstructor, @AllArgsConstructor

Type Mappings

Java Type	PostgreSQL	Notes
`String`	`VARCHAR(255)`	Default
`String` + `@Lob`	`TEXT`	For long text
`BigDecimal`	`NUMERIC(precision, scale)`	For monetary values
`Instant`	`TIMESTAMP WITH TIME ZONE`	For timestamps
`LocalDate`	`DATE`	For dates only
`UUID`	`UUID`	Native PostgreSQL
`enum`	`VARCHAR`	With `@Enumerated(EnumType.STRING)`

Relationships

ManyToOne (owning side)

java

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

OneToMany (inverse side)

java

@OneToMany(mappedBy = "category", cascade = CascadeType.ALL, orphanRemoval = true)
@Builder.Default
private List<Product> products = new ArrayList<>();

ManyToMany

java

@ManyToMany
@JoinTable(
    name = "product_tags",
    joinColumns = @JoinColumn(name = "product_id"),
    inverseJoinColumns = @JoinColumn(name = "tag_id")
)
@Builder.Default
private Set<Tag> tags = new HashSet<>();

Indexes and Constraints

java

@Table(
    name = "products",
    indexes = {
        @Index(name = "idx_product_name", columnList = "name"),
        @Index(name = "idx_product_category", columnList = "category_id")
    },
    uniqueConstraints = {
        @UniqueConstraint(name = "uk_product_sku", columnNames = "sku")
    }
)

User Entity for Authentication

For User entities implementing Spring Security:

java

@Entity
@Table(name = "users")
@EntityListeners(AuditingEntityListener.class)
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class User implements UserDetails {

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

    @Column(nullable = false, unique = true)
    private String email;

    @Column(nullable = false)
    private String password;

    @Enumerated(EnumType.STRING)
    @Column(nullable = false)
    @Builder.Default
    private Role role = Role.USER;

    @Column(nullable = false)
    @Builder.Default
    private boolean enabled = true;

    @CreatedDate
    @Column(nullable = false, updatable = false)
    private Instant createdAt;

    @LastModifiedDate
    @Column(nullable = false)
    private Instant updatedAt;

    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        return List.of(new SimpleGrantedAuthority("ROLE_" + role.name()));
    }

    @Override
    public String getUsername() {
        return email;
    }
}

Configuration Required

Enable JPA auditing:

java

@Configuration
@EnableJpaAuditing
public class JpaConfig {
}