我正在尝试做一个简单的Spring应用程序。它需要公开REST端点并将其保存到关系数据库中。
我接受了您的示例项目http://spring.io/guides/gs/accessing-data- rest/。如您的指南中所述,我能够执行所有操作(POST,PATCH,PUT,GET)。
但是,我尝试为Person Entity类添加关系,事情开始崩溃。
@Entity public class Person { @Id @GeneratedValue(strategy = GenerationType.AUTO) private long id; private String firstName; private String lastName; @OneToOne(cascade = {CascadeType.ALL}) private PersonDetails personDetails; @OneToOne(cascade = {CascadeType.ALL}) private PersonChildren personChildren; ///Getter and setters for everything except id. } @Entity public class PersonChildren { @Id @GeneratedValue(strategy = GenerationType.AUTO) private long id; private String childFirstName; private String childLastName; @OneToOne(mappedBy="personChildren", optional=false) private Person person; ///Getter and setters for everything except id. } @Entity public class PersonDetails { @Id @GeneratedValue(strategy = GenerationType.AUTO) private long id; private String email; private String phoneNumber; @OneToOne(mappedBy="personDetails",optional=false) private Person person; ///Getter and setters for everything except id. } @RepositoryRestResource(collectionResourceRel = "people", path = "people") public interface PersonRepository extends PagingAndSortingRepository<Person, Long> { List<Person> findByLastName(@Param("name") String name); }
build.gradle
buildscript { repositories { maven { url "http://repo.spring.io/libs-release" } mavenLocal() mavenCentral() } dependencies { classpath("org.springframework.boot:spring-boot-gradle-plugin:1.1.1.RELEASE") } } apply plugin: 'java' apply plugin: 'eclipse' apply plugin: 'idea' apply plugin: 'spring-boot' jar { baseName = 'gs-accessing-data-rest' version = '0.1.0' } repositories { mavenLocal() mavenCentral() maven { url "http://repo.spring.io/libs-release" } } dependencies { compile("org.springframework.boot:spring-boot-starter-web") compile("org.springframework.boot:spring-boot-starter-data-jpa") compile("com.h2database:h2") compile("org.springframework.data:spring-data-rest-webmvc") } task wrapper(type: Wrapper) { gradleVersion = '1.11' }
呼叫:
$ curl -i -X POST -H "Content-Type:application/json" -d '{ "firstName":"John", "lastName": "Doe", "personDetails": { "email": "john@gmail.com", "phoneNumber": "001-002-0003" }, "personChildren": {"childFirstName": "Mary", "childLastName": "Martin" } }' <code> http://localhost:8080/people </code> Response: HTTP/1.1 201 Created Server: Apache-Coyote/1.1 <code> Location: http://localhost:8080/people/1 </code> Content-Length: 0 Date: Thu, 26 Jun 2014 05:42:45 GMT $ curl http://localhost:8080/people { "timestamp" : 1403761371011, "status" : 500, "error" : "Internal Server Error", "exception" : "org.springframework.http.converter.HttpMessageNotWritableException", "message" : "Could not write JSON: Detected multiple association links with same relation type! Disambiguate association @javax.persistence.OneToOne(optional=false, targetEntity=void, cascade=[], fetch=EAGER, orphanRemoval=false, mappedBy=personChildren) private com.ds.dao.rest.Person com.ds.dao.rest.PersonChildren.person using @RestResource! (through reference chain: org.springframework.hateoas.PagedResources[\"_embedded\"]->java.util.UnmodifiableMap[\"people\"]->java.util.ArrayList[0]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Detected multiple association links with same relation type! Disambiguate association @javax.persistence.OneToOne(optional=false, targetEntity=void, cascade=[], fetch=EAGER, orphanRemoval=false, mappedBy=personChildren) private com.ds.dao.rest.Person com.ds.dao.rest.PersonChildren.person using @RestResource! (through reference chain: org.springframework.hateoas.PagedResources[\"_embedded\"]->java.util.UnmodifiableMap[\"people\"]->java.util.ArrayList[0])", "path" : "/people" }
问题1:我可以发表文章,但我的GET一直失败。
问题2:发布成功后,为什么会出现此错误?
问题3:是否有很好的Spring指南对REST和JPA有帮助?如果您仍在使用这些模块,我可以看什么示例?
问题4:@RepositoryRestResource是问题吗?除非我添加spring-data-rest-webmvc作为依赖项,否则无法识别。
这类似于未回答的问题, Spring Data Rest歧义关联异常
更新 :
它仅OneToOne在Person类中使用一个映射。如果我想补充的两个类,personDetails并personChildren在Person与OneToOne映射。它不起作用。
OneToOne
Person
personDetails
personChildren
我也尝试添加@JointColumn(name="person_details")和@JointColumn(name="person_children")以personDetails和personChildren。它也不起作用。
@JointColumn(name="person_details")
@JointColumn(name="person_children")
这样做的原因很简单:关联实体的关系名称是从包含类的属性名称派生的。因此,无论PersonDetails并且PersonChildren要创建出站链接到一个Person名为person。如果我们渲染的话,看起来会像这样
PersonDetails
PersonChildren
person
{ _links : { person : { href : … }, <- the one from PersonDetails person : { href : … } <- the one from PersonChildren }
这当然是无效的。而且,将两个链接排列在一个数组中将使您无法再区分两个链接(哪个来自PersonDetails哪个链接,哪个来自哪个链接PersonChildren。)。
因此,这里有一些选择:
@RestResource
rel
exported
false