Exporting Spring Data JPA Repositories as REST Services using Spring Data REST

Spring Data modules provides various modules to work with various types of datasources like RDBMS, NOSQL stores etc in unified way. In my previous article  SpringMVC4 + Spring Data JPA + SpringSecurity configuration using JavaConfig I have explained how to configure Spring Data JPA using JavaConfig.

Now in this post let us see how we can use Spring Data JPA repositories and export JPA entities as REST endpoints using Spring Data REST.

First let us configure spring-data-jpa and spring-data-rest-webmvc dependencies in our pom.xml.

	<dependency>
	<groupId>org.springframework.data</groupId>
	<artifactId>spring-data-jpa</artifactId>
	<version>1.5.0.RELEASE</version>
	</dependency>
	<dependency>
	<groupId>org.springframework.data</groupId>
	<artifactId>spring-data-rest-webmvc</artifactId>
	<version>2.0.0.RELEASE</version>
	</dependency>

view raw spring-data-rest-pom.xml hosted with ❤ by GitHub

Make sure you have latest released versions configured correctly, otherwise you will encounter the following error:
java.lang.ClassNotFoundException: org.springframework.data.mapping.SimplePropertyHandler

Create JPA entities.

	@Entity
	@Table(name = "USERS")
	public class User implements Serializable
	{
	private static final long serialVersionUID = 1L;
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "user_id")
	private Integer id;
	@Column(name = "username", nullable = false, unique = true, length = 50)
	private String userName;
	@Column(name = "password", nullable = false, length = 50)
	private String password;
	@Column(name = "firstname", nullable = false, length = 50)
	private String firstName;
	@Column(name = "lastname", length = 50)
	private String lastName;
	@Column(name = "email", nullable = false, unique = true, length = 50)
	private String email;
	@Temporal(TemporalType.DATE)
	private Date dob;
	private boolean enabled=true;
	@OneToMany(fetch=FetchType.EAGER, cascade=CascadeType.ALL)
	@JoinColumn(name="user_id")
	private Set<Role> roles = new HashSet<>();
	@OneToMany(mappedBy = "user")
	private List<Contact> contacts = new ArrayList<>();
	//setters and getters
	}
	@Entity
	@Table(name = "ROLES")
	public class Role implements Serializable
	{
	private static final long serialVersionUID = 1L;
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "role_id")
	private Integer id;
	@Column(name="role_name",nullable=false)
	private String roleName;
	//setters and getters
	}
	@Entity
	@Table(name = "CONTACTS")
	public class Contact implements Serializable
	{
	private static final long serialVersionUID = 1L;
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "contact_id")
	private Integer id;
	@Column(name = "firstname", nullable = false, length = 50)
	private String firstName;
	@Column(name = "lastname", length = 50)
	private String lastName;
	@Column(name = "email", nullable = false, unique = true, length = 50)
	private String email;
	@Temporal(TemporalType.DATE)
	private Date dob;
	@ManyToOne
	@JoinColumn(name = "user_id")
	private User user;
	//setters and getters
	}

view raw SampleEntities.java hosted with ❤ by GitHub

Configure DispatcherServlet using AbstractAnnotationConfigDispatcherServletInitializer.

Observe that we have added RepositoryRestMvcConfiguration.class to getServletConfigClasses() method.
RepositoryRestMvcConfiguration is the one which does the heavy lifting of looking for Spring Data Repositories and exporting them as REST endpoints.

	package com.sivalabs.springdatarest.web.config;
	import javax.servlet.Filter;
	import org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration;
	import org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter;
	import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
	import com.sivalabs.springdatarest.config.AppConfig;
	public class SpringWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer
	{
	@Override
	protected Class<?>[] getRootConfigClasses()
	{
	return new Class<?>[] { AppConfig.class};
	}
	@Override
	protected Class<?>[] getServletConfigClasses()
	{
	return new Class<?>[] { WebMvcConfig.class, RepositoryRestMvcConfiguration.class };
	}
	@Override
	protected String[] getServletMappings()
	{
	return new String[] { "/rest/*" };
	}
	@Override
	protected Filter[] getServletFilters() {
	return new Filter[]{
	new OpenEntityManagerInViewFilter()
	};
	}
	}

view raw SpringDataREST-SpringWebAppInitializer.java hosted with ❤ by GitHub

Create Spring Data JPA repositories for JPA entities.

	public interface UserRepository extends JpaRepository<User, Integer>
	{
	}
	public interface RoleRepository extends JpaRepository<Role, Integer>
	{
	}
	public interface ContactRepository extends JpaRepository<Contact, Integer>
	{
	}

view raw JPARepositories.java hosted with ❤ by GitHub

That's it. Spring Data REST will take care of rest of the things.

You can use spring Rest Shell https://github.com/spring-projects/rest-shell or Chrome's Postman Addon to test the exported REST services.

D:\rest-shell-1.2.1.RELEASE\bin>rest-shell
http://localhost:8080:>

Now we can change the baseUri using baseUri command as follows:
http://localhost:8080:>baseUri http://localhost:8080/spring-data-rest-demo/rest/
http://localhost:8080/spring-data-rest-demo/rest/>


http://localhost:8080/spring-data-rest-demo/rest/>list
rel         href
======================================================================================
users       http://localhost:8080/spring-data-rest-demo/rest/users{?page,size,sort}
roles       http://localhost:8080/spring-data-rest-demo/rest/roles{?page,size,sort}
contacts    http://localhost:8080/spring-data-rest-demo/rest/contacts{?page,size,sort}

Note: It seems there is an issue with rest-shell when the DispatcherServlet url mapped to "/" and issue list command it responds with "No resources found".

http://localhost:8080/spring-data-rest-demo/rest/>get users/

	{
	"_links": {
	"self": {
	"href": "http://localhost:8080/spring-data-rest-demo/rest/users/{?page,size,sort}",
	"templated": true
	},
	"search": {
	"href": "http://localhost:8080/spring-data-rest-demo/rest/users/search"
	}
	},
	"_embedded": {
	"users": [
	{
	"userName": "admin",
	"password": "admin",
	"firstName": "Administrator",
	"lastName": null,
	"email": "admin@gmail.com",
	"dob": null,
	"enabled": true,
	"_links": {
	"self": {
	"href": "http://localhost:8080/spring-data-rest-demo/rest/users/1"
	},
	"roles": {
	"href": "http://localhost:8080/spring-data-rest-demo/rest/users/1/roles"
	},
	"contacts": {
	"href": "http://localhost:8080/spring-data-rest-demo/rest/users/1/contacts"
	}
	}
	},
	{
	"userName": "siva",
	"password": "siva",
	"firstName": "Siva",
	"lastName": null,
	"email": "sivaprasadreddy.k@gmail.com",
	"dob": null,
	"enabled": true,
	"_links": {
	"self": {
	"href": "http://localhost:8080/spring-data-rest-demo/rest/users/2"
	},
	"roles": {
	"href": "http://localhost:8080/spring-data-rest-demo/rest/users/2/roles"
	},
	"contacts": {
	"href": "http://localhost:8080/spring-data-rest-demo/rest/users/2/contacts"
	}
	}
	}
	]
	},
	"page": {
	"size": 20,
	"totalElements": 2,
	"totalPages": 1,
	"number": 0
	}
	}

view raw response.json hosted with ❤ by GitHub

You can find the source code at https://github.com/sivaprasadreddy/sivalabs-blog-samples-code/tree/master/spring-data-rest-demo
For more Info on Spring Rest Shell: https://github.com/spring-projects/rest-shell