Create the Tag Entity

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In our previous lessons, we created the User and Category entities to handle user management and content organization.

Now we'll implement the Tag entity, which provides a more flexible way to classify and organize blog posts.

Understanding Tags in Blog Systems

Tags represent keywords or phrases that describe specific aspects of blog content.

This flexibility allows content creators to precisely describe their posts and helps readers find exactly what they're looking for.

Implementing the Tag Entity

Here's our implementation of the Tag entity:

package com.devtiro.blog.domain.entities;

import jakarta.persistence.*;
import lombok.*;

import java.util.ArrayList;
import java.util.Objects;
import java.util.Set;
import java.util.UUID;

@Entity
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder
@Table(name = "tags")
public class Tag {
    @Id
    @GeneratedValue(strategy = GenerationType.UUID)
    private UUID id;

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

    // Custom equals/hashCode implementation needed instead of Lombok's
    // to avoid issues with JPA entity lifecycle management
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Tag tag = (Tag) o;
        return Objects.equals(id, tag.id) &&
               Objects.equals(name, tag.name);
    }

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

Entity Design Considerations

The unique constraint on the name field ensures we don't have duplicate tags in our system.

Summary

Tags provide flexible, non-hierarchical content classification
The unique constraint on tag names prevents duplicates while allowing multiple posts per tag
Custom equals and hashCode implementations ensure proper JPA entity behavior