Spring Data JPA

dependencies {
    implementation("org.springframework.boot:spring-boot-starter-data-jpa")
    runtimeOnly("org.postgresql:postgresql")
}

⚠️ Убираем spring-boot-starter-jdbc — он не нужен, JPA приносит свой DataSource.

package com.taskflow.model;

import jakarta.persistence.*;
import java.time.Instant;
import java.util.Objects;

@Entity
@Table(name = "tasks")
public class Task {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false, length = 200)
    private String title;

    @Column(columnDefinition = "TEXT")
    private String description;

    @Column(nullable = false)
    private boolean done = false;

    @Column(name = "created_at", nullable = false, updatable = false)
    private Instant createdAt;

    @Column(name = "updated_at", nullable = false)
    private Instant updatedAt;

    public Task() {}

    public Task(String title, String description) {
        this.title = title;
        this.description = description;
    }

    @PrePersist
    void onCreate() {
        Instant now = Instant.now();
        this.createdAt = now;
        this.updatedAt = now;
    }

    @PreUpdate
    void onUpdate() {
        this.updatedAt = Instant.now();
    }

    // Getters / Setters
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getTitle() { return title; }
    public void setTitle(String title) { this.title = title; }
    public String getDescription() { return description; }
    public void setDescription(String description) { this.description = description; }
    public boolean isDone() { return done; }
    public void setDone(boolean done) { this.done = done; }
    public Instant getCreatedAt() { return createdAt; }
    public Instant getUpdatedAt() { return updatedAt; }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof Task task)) return false;
        return Objects.equals(id, task.id);
    }

    @Override
    public int hashCode() {
        return Objects.hash(id);
    }
}

Ключевые моменты:

• @PrePersist / @PreUpdate — JPA-колбэки, вызываются перед INSERT/UPDATE
• equals/hashCode по id (теперь id всегда есть после persist)
• updatable = false на createdAt — нельзя изменить после создания
• private поля + геттеры/сеттеры (стандарт для JPA, не для record)

package com.taskflow.repository;

import com.taskflow.model.Task;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public interface TaskRepository extends JpaRepository {
    List findByDone(boolean done);
    List findByTitleContainingIgnoreCase(String title);
}

Магия Spring Data JPA: ты пишешь имя метода → Spring парсит → генерирует SQL.

• findByDone → SELECT * FROM tasks WHERE done = ?
• findByTitleContainingIgnoreCase → SELECT * FROM tasks WHERE LOWER(title) LIKE LOWER('%' || ? || '%')

Поддерживаемые ключевые слова: findBy, countBy, deleteBy, And, Or, Containing, IgnoreCase, OrderBy, Top, Distinct, Between, LessThan, GreaterThan, IsNull, In, NotIn...

package com.taskflow.service;

import com.taskflow.model.Task;
import com.taskflow.repository.TaskRepository;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

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

@Service
public class TaskService {
    private final TaskRepository repo;

    public TaskService(TaskRepository repo) {
        this.repo = repo;
    }

    public List findAll() { return repo.findAll(); }
    public List findByDone(boolean done) { return repo.findByDone(done); }
    public Optional findById(Long id) { return repo.findById(id); }

    @Transactional
    public Task create(Task task) { return repo.save(task); }

    @Transactional
    public Optional update(Long id, Task task) {
        return repo.findById(id).map(existing -> {
            existing.setTitle(task.getTitle());
            existing.setDescription(task.getDescription());
            existing.setDone(task.isDone());
            return repo.save(existing);
        });
    }

    @Transactional
    public boolean delete(Long id) {
        if (!repo.existsById(id)) return false;
        repo.deleteById(id);
        return true;
    }
}

spring:
  jpa:
    hibernate:
      ddl-auto: validate   # НЕ создаёт таблицы сам — Flyway уже создал
    show-sql: true         # печатает SQL в консоль
    properties:
      hibernate.format_sql: true
      hibernate.dialect: org.hibernate.dialect.PostgreSQLDialect
    open-in-view: false    # убираем lazy-loading warning'и (см. вопрос 4)

./gradlew bootRun

Проверяем:

$ curl -X POST http://localhost:8080/api/tasks \
  -H "Content-Type: application/json" \
  -d '{"title":"Read JPA docs","description":"Understand @Entity","done":false}'

# В консоли увидишь SQL:
# Hibernate: insert into tasks (created_at, description, done, title, updated_at) values (?, ?, ?, ?, ?)
# Hibernate: select t1_0.id, t1_0.created_at, ... from tasks t1_0 where t1_0.id=?

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