[FIXED] Don't understand how Spring (Boot) Data REST is told to create API endpoints

Issue

I have currently have an application that is using Spring Boot and Spring Data. I have my domain objects that were reverse engineered from my database and I have several repositories (classes). Each repository is an interface that extends the CrudRepository.

import org.springframework.data.repository.CrudRepository

interface MyDomainClassRepository extends CrudRepository<MyDomainClass, Integer> {
     private MyDomainClass findByName(String name);
}

At this point I would create a service that would implement these items. The service would then be called by a REST controller.

I wanted to be able to have Spring create my REST API automatically if possible and I found the Spring Data REST project. I found this http://spring.io/guides/gs/accessing-data-rest/ and I can follow that guide, but I don't understand what is enabling the "REST APIs" to be created "automatically". I could understand it if the @RepositoryRestResource annotation caused the API to be created but in that guide it explicitly says

RepositoryRestResource is not required for a repository to be exported. It is only used to change the export details, such as using /people instead of the default value of /persons.

Does including in my POM file and rebuilding "automatically" allow Spring Data to create the REST endpoints?

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-rest</artifactId>
    </dependency>

What keyword, section am I missing that makes it so the API endpoint is created automatically?

Solution

Spring Boot is opinionated. It has opinions like using tomcat as your application server or logback as your logging utility. When you pull in

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-rest</artifactId>
</dependency>

It has opinions that when it detects (by classpath scanning) interfaces/classes that extend/implement Repository it will assume that those classes should be served as RESTful resources. RestRepository allows you to customize this behavior by changing the endpoint or not serving the resource at all (exported = false).

Spring-Data-REST does automatically setup the resource to handle GET/POST/PUT/DELETE requests. Are you familiar with REST/HTTP? Those would not be discrete endpoints, GET/PUT/POST/DELETE are http verbs, so there wouldn't be a resource/1/delete endpoint.

Answered By - Billy Korando
Answer Checked By - Marilyn (JavaFixing Volunteer)