Скачать или смотреть Persisting an Enum as a String in Hibernate 6 with Spring Boot 3 without External Libraries

Discover how to efficiently persist an `enum` as a `string` in Hibernate 6 using Spring Boot 3, specifically targeting PostgreSQL. Learn about using `ColumnTransformers` and avoiding external dependencies!
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Persisting an Enum as a String in Hibernate 6 with Spring Boot 3

Managing enums in databases can be tricky, especially when different technologies and frameworks intersect. If you're using PostgreSQL with Spring Boot 3 and Hibernate 6, you might encounter a situation where you need to store an enum as a string in the database. This post addresses how to achieve this without relying on external libraries like hibernate-types-62, which many resources suggest.

The Problem

Suppose you have the following PostgreSQL setup:

Database Setup

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You also have a corresponding JPA entity:

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Attempting to persist this entity results in an error because Hibernate tries to save the enum as a string, which is not compatible with the database's enum type.

The Solution: Using ColumnTransformers

The key to elegantly handling this situation in Hibernate 6 is to use ColumnTransformers. This allows you to manipulate the SQL generated by Hibernate and ensure that the correct type is written to the database.

Updated Entity Example

Here's how you can adjust your entity to include a ColumnTransformer:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Solution

Using @ ColumnTransformer:

This annotation modifies the SQL statement Hibernate sends to the database. By specifying write = "?::TEST_TYPE", you instruct Hibernate to cast the string to the appropriate PostgreSQL enum type during insert/update operations.

Handling Different Schemas:

If your enum resides in a different schema, you can adjust the ColumnTransformer like this:

[[See Video to Reveal this Text or Code Snippet]]

How It Works:

When saving the entity, Hibernate uses the @ Enumerated(EnumType.STRING) annotation to handle the enum as a string. The ColumnTransformer then takes that string value and casts it to the corresponding enum type for saving to the database. When fetching, Hibernate again uses the string representation to return the correct enum.

Why This Approach?

Simplicity: This solution does not require additional complexities like creating custom UserTypes or relying on external utilities.

Versatility: It can be adapted for various database schemas and is easy to understand.

Conclusion

Persisting an enum as a string in Hibernate 6 within Spring Boot 3 can be done smoothly with the help of ColumnTransformers. This method is straightforward and negates the need for external libraries, making it an efficient option for your applications.

By following the guidelines provided in this post, you can effectively manage enum types in PostgreSQL while keeping your code clean and maintainable.