spring-boot-demo/crud-mysql

crud-mysql

Companion project for the article Spring Boot CRUD REST API with MySQL and Spring Data JPA on ankurm.com.

A complete Create / Read / Update / Delete API for books on Spring Boot 4.1, Spring Data JPA (Hibernate), Flyway and MySQL 8.4, with Bean Validation and RFC 9457 ProblemDetail errors. Every console block quoted in the article came out of output/, written by the test suite against a real MySQL server, so a claim that stops being true turns the build red.

There is deliberately no docs/ folder: the deeper material lives in collapsible sections inside the article itself.

Versions

Spring Boot	4.1.1
Spring Framework	7.0.9
MySQL server used for output/	MySQL Community Server 8.4.6 (official Linux tarball, started directly; not Docker)
MySQL driver	MySQL Connector/J 9.7.0 (what Boot 4.1.1 manages)
JDK	21 (OpenJDK 21.0.12)
Maven	3.9

Only JDK 21 was used. docker-compose.yml was not run (the sandbox had no Docker).

Quickstart

docker compose up -d                  # or run scripts/mysql-setup.sql against a MySQL you already have
mvn test                              # runs the scenarios and rewrites output/01-04
mvn spring-boot:run                   # API on http://localhost:8080/api/books

Defaults: jdbc:mysql://localhost:3306/library, user library, password library. Override with DB_URL, DB_USER and DB_PASSWORD. The tests start the real application and delete all rows in the book table first, so point them at a database you can wipe.

Endpoints

Method and path	What it does	Success	Errors
POST /api/books	create	201 + Location	400 validation, 409 duplicate ISBN
GET /api/books/{id}	read one	200	404, 400 (id not a number)
GET /api/books?author=&page=&size=	list, paged, optional author filter	200
PUT /api/books/{id}	replace	200	400, 404, 409
DELETE /api/books/{id}	delete	204	404

Source layout

Path	What it is
book/Book.java	the JPA entity, mapped to the book table
book/BookRepository.java	a Spring Data interface: no implementation to write
book/BookService.java	transactions, paging, dirty checking for the update
book/BookController.java	the HTTP layer
book/BookRequest.java, BookResponse.java, PageResponse.java	what crosses the wire
error/ApiExceptionHandler.java	every error becomes a ProblemDetail
resources/db/migration/V1__create_book.sql	the schema, owned by Flyway

Captured output

File	What it shows
01-mysql-and-schema.txt	the server and driver versions, the Hibernate dialect, the Flyway history and SHOW CREATE TABLE
02-crud-walkthrough.txt	create, read, list (paged and filtered), update, delete: the requests are made with the JDK's HttpClient and printed as the equivalent curl commands, with the real responses
03-error-responses.txt	validation, duplicate ISBN on create and on update, the message MySQL itself returned, 404, bad id, bad JSON
04-sql-per-request.txt	the SQL Hibernate sent for each kind of request
05-real-curl.txt	real curl -i against the packaged jar (headers included), written by scripts/curl-demo.sh