Spring + GraphQL Example

This is a sample project featuring Spring with data exposed through GraphQL.

Challenges Solved

Related to GraphQL:

• Expose GraphQL using Spring controller
• Access JPA repository using GraphQL
• Filtering data based on GraphQL query
• Completely avoiding manually writing GraphQL schemas to resources

Unrelated:

• Use Project Lombok to bytecode-weave-in boilerplate code
• Use in-memory H2 database with JPA
• Use Spring Boot autoconfiguration to stand up JDBC

Other Learnings

• If you use H2, you may add the following properties to enable H2 web UI: spring.h2.console.enabled=true and spring.h2.console.path=/whatever, then access it on /whatever.
• H2 does not fail if you connect to a database which does not exist, so if you use the web UI, make sure to connect to jdbc:h2:mem:testdb to hit the in-memory database. Otherwise, a flat-file database will be created.
• Lombok's @Data annotation is unfortunately not 100% suitable for JPA entities; I recommend also adding @RequiredArgsConstructor and @NoArgsConstructor.

Opinion Zone

• GraphQL and REST are not interchangeable; neither is a magic bullet.
• REST is more of an architectural structure, whereas GraphQL is "just" a data query specification.
• Although it is uncommonly embraced fully, REST focuses more on hypermedia controls than it does data query.
• If you are not actually designing a RESTful API (i.e. creating a RPC over HTTP API), GraphQL might be a good solution for you, as it enforces its own conventions.
• GraphQL makes it easier to deprecate things (field usage is specified by the client, not the server).
• GraphQL decouples client evolution from server evolution. Then again, so does REST if you use HATEOAS.
• GraphQL is pretty cool and I will use it in addition to my REST structure.