Over a million developers have joined DZone.

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

Build fast, scale big with MongoDB Atlas, a hosted service for the leading NoSQL database. Try it now! Brought to you in partnership with MongoDB.

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>


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
}


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()
       };
    } 
}



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>
{
}


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
    }
}

Now it's easier than ever to get started with MongoDB, the database that allows startups and enterprises alike to rapidly build planet-scale apps. Introducing MongoDB Atlas, the official hosted service for the database on AWS. Try it now! Brought to you in partnership with MongoDB.

Topics:
java ,frameworks ,spring ,tips and tricks

Published at DZone with permission of Siva Prasad Reddy Katamreddy, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

The best of DZone straight to your inbox.

SEE AN EXAMPLE
Please provide a valid email address.

Thanks for subscribing!

Awesome! Check your inbox to verify your email so you can start receiving the latest in tech news and resources.
Subscribe

{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}