Spring Data REST: Silent failure when adding entity relationship

Question

Fellow Spring Data REST enthusiasts, I am running my Spring Data REST 1.1 application, and I am attempting use curl to add an entity relationship using the "text/uri-list" Content-type, as described in the link: Example-API-usage-with-curl.

curl -v -d "http://localhost:8080/simplemvc/rest/enemies/3" -H "Content-Type: text/uri-list" http://localhost:8080/simplemvc/rest/heroes/1/defeatedEnemies

Unfortunately, although the server returns "201 Created", the body contains an empty JSON object, and the entity relationship does not get created:

{
  "links" : [ ],
  "content" : [ ]
}

I would expect to see a SQL UPDATE being executed, but analyzing the SQL reveals that only SELECT statements occur:

Hibernate: select hero0_.HERO_ID as HERO1_1_0_, hero0_.name as name2_1_0_ from HERO hero0_ where hero0_.HERO_ID=?
Hibernate: select defeateden0_.HERO_ID as HERO4_1_1_, defeateden0_.ENEMY_ID as ENEMY1_0_1_, defeateden0_.ENEMY_ID as ENEMY1_0_0_, defeateden0_.description as descript2_0_0_, defeateden0_.HERO_ID as HERO4_0_0_, defeateden0_.name as name3_0_0_ from ENEMY defeateden0_ where defeateden0_.HERO_ID=?
Hibernate: select enemy0_.ENEMY_ID as ENEMY1_0_1_, enemy0_.description as descript2_0_1_, enemy0_.HERO_ID as HERO4_0_1_, enemy0_.name as name3_0_1_, hero1_.HERO_ID as HERO1_1_0_, hero1_.name as name2_1_0_ from ENEMY enemy0_ left outer join HERO hero1_ on enemy0_.HERO_ID=hero1_.HERO_ID where enemy0_.ENEMY_ID=?

Interestingly, if I "manually" add a relationship by executing a SQL statement in my database client:

UPDATE ENEMY SET HERO_ID = 1 WHERE ENEMY_ID = 1;

and then execute the curl statement:

curl -v -H "Accept: application/json" http://localhost:8080/simplemvc/rest/heroes/1/defeatedEnemies

I get a JSON representation that demonstrates -- via hypermedia links -- that Spring Data REST recognizes the one-to-many relationship between the Hero and Enemy entities:

{
  "links" : [ ],
  "content" : [ {
    "name" : "Red Ghost",
    "description" : "Likes to chase",
    "links" : [ {
      "rel" : "self",
      "href" : "http://localhost:8080/simplemvc/rest/enemies/1"
    }, {
      "rel" : "enemy.enemy.hero",
      "href" : "http://localhost:8080/simplemvc/rest/enemies/1/hero"
    } ]
  } ]
}

This is an existing Spring MVC app to which Spring Data REST is being added, using the following article as a guide: Adding-Spring-Data-REST-to-an-existing-Spring-MVC-Application

I have tried using both H2 and MySQL databases with the same result. Below are my JPA entities, Spring Data JPA Repositories, application context, and web.xml:

Hero.java

@Entity
@Table(name = "HERO")
public class Hero {

    @TableGenerator(
            name="heroGen", 
            table="ID_GEN", 
            pkColumnName="GEN_KEY", 
            valueColumnName="GEN_VALUE", 
            pkColumnValue="HERO_ID", 
            allocationSize=1)
    @Id
    @GeneratedValue(strategy=TABLE, generator="heroGen")
    @Column(name = "HERO_ID")
    private Integer id;

    @Column
    private String name;

    @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "hero")
    private Set<Enemy> defeatedEnemies;

    ...
}

Enemy.java

@Entity
@Table(name = "ENEMY")
public class Enemy {

    @TableGenerator(name="enemyGen", 
            table="ID_GEN", 
            pkColumnName="GEN_KEY", 
            valueColumnName="GEN_VALUE", 
            pkColumnValue="ENEMY_ID", 
            allocationSize=1)
    @Id
    @GeneratedValue(strategy=TABLE, generator="enemyGen")
    @Column(name="ENEMY_ID")
    private Integer id;

    @Column
    private String name;

    @Column
    private String description;

    @ManyToOne
    @JoinColumn(name = "HERO_ID")
    private Hero hero;

    ...
}

HeroRepository.java

@RestResource(path = "heroes")
public interface HeroRepository extends CrudRepository<Hero, Integer> {

}

EnemyRepository.java

@RestResource(path = "enemies")
public interface EnemyRepository extends CrudRepository<Enemy, Integer> {

}

root-context.xml includes:

<jpa:repositories base-package="com.simple.simplemvc.repositories" />   

<bean id="restConfig" class="org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration"/>

web.xml includes:

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/spring/root-context.xml</param-value>
</context-param>

<servlet>
    <servlet-name>rest-dispatcher</servlet-name>
    <servlet-class>org.springframework.data.rest.webmvc.RepositoryRestDispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>rest-dispatcher</servlet-name>
    <url-pattern>/rest/*</url-pattern>
</servlet-mapping>

Any ideas? Thanks!

Answer 1

To add relation between existing entities try POST with

Content-Type: application/json

on

http://localhost:8080/simplemvc/rest/enemies/3

with body

{"hero":"http://localhost:8080/simplemvc/rest/heroes/1"}

To add new Enemy entity with relation to hero try POST on

http://localhost:8080/simplemvc/rest/enemies

with body

{"name":"Enemy name", "description":"Enemy description", "hero":"http://localhost:8080/simplemvc/rest/heroes/1"}

Tested on spring-data-rest-webmvc version 2.2.0.RELEASE

Answer 2

I think you are facing the same problem I asked about here:

Spring Data Rest, Many to one

The answer solves the problem of adding an entity on the Many side of a relationship, though not using the "text/uri-list".