Overview When it comes to data integrity, the famous example that people usually mention is the bank transfer scenario: Alice sends money to Bob, and Bob sends money to Alice. I also read that using @Transactional is the solution for such cases. However, is using @Transactional annotation enough to make Alice and Bob happy? Let’s … Read more
Overview @ManyToOne and @OneToMany are standard mappings in Hibernate. Understanding how to use them correctly is the key to mapping entities efficiently in Hibernate. In this post, I will show you how to use these annotations and give examples to demonstrate use cases. The analogy I use is schools and students. In real life, schools … Read more
Overview One of the lesser-known yet powerful annotations in Hibernate is @ColumnTransformer. This annotation let us apply SQL transformations on entity properties when interacting with the database. You can think of this annotation as a two way converter. A real life use case Let’s consider a weather app that initially use Kelvin scale to store … Read more
Overview In this post, we are going to explore the reasons why does Hibernate need a no-arg constructor. The no-arg constructor need to be protected or public. A primer on the no-arg constructor When you declare a class without any constructor, the compiler create a default no-arg constructor for you. However, when you define constructor(s) … Read more
Overview There are times you work with legacy databases that store boolean values as strings. Let’s consider this example: Town A conducted a survey to see if their citizens like apples or not. The developer back then created a table like this: For the file like_apple, he planned to store LIKE and DONOT as values … Read more
Let’s consider an example. You have been working on a website selling phones since 2000. In early 2000, there wasn’t any smartphone so you may created an object Phone like this: I’m using lombok (in case you find @Data strange). So, back in 2000s, phones were simple like that. However, with the appearance of smartphone. … Read more