Child Entity Not Being Deleted with FetchType Eager on Parent with Bidirectional mapping

Introduction

In the world of Java persistence with Hibernate, managing relationships between entities is a common challenge. One particular scenario that often causes confusion is when a child entity is not deleted even though it seems like it should be. This issue frequently arises when using FetchType.EAGER on the parent entity, which eagerly fetches associated entities. In this blog post, we'll delve into why this happens, the workings of Hibernate, different fetch types, and how to address this problem.

Hibernate Working

Hibernate is an object-relational mapping (ORM) tool for Java, providing a framework for mapping an object-oriented domain model to a traditional relational database. When entities are configured with relationships, Hibernate manages these relationships based on specified mappings. This includes fetching associated entities when needed based on the FetchType specified.

EAGER vs LAZY Loading

The choice between EAGER and LAZY loading depends on the specific requirements of your application. While EAGER loading can simplify data retrieval and access, it may lead to performance issues, especially when dealing with large datasets or deeply nested relationships. LAZY loading, although more efficient in terms of resource usage, requires careful management to avoid unexpected behavior like the one we're addressing in this post.

How deleteById(...) works

In the provided code snippet, the deleteById() method is used to delete an Address[child] entity by its ID. However, when FetchType.EAGER is used to fetch the associated Address[child] entities within the Student[parent] entity, deleting an Address directly may not remove its association from the Student entity. This is because Hibernate will not automatically manage the associations between entities when deleting a child entity.

#Java #SpringBoot #JPA #Hibernate #Developer #SoftwareEngineer