在@ManytoMany 关系和具有额外列的查找表的情况下，无法检索 Spring HATEOAS 嵌入的资源对象

本文介绍了在@ManytoMany 关系和具有额外列的查找表的情况下，无法检索 Spring HATEOAS 嵌入的资源对象的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 29岁程序员，3月因学历无情被辞！ 我无法检索嵌入式.我正在使用 Spring boot、spring data rest 和 spring JPA.我在数据库中有 3 个表用户能力user_competency(带有额外列的连接/复合表)用户@Entity@Table(name = "\"user\"", schema = "public")@JsonIdentityInfo(生成器 = ObjectIdGenerators.IntSequenceGenerator.class,属性 = "用户 ID")公共类用户实现 java.io.Serializable {私人长用户ID；@Id @GeneratedValue(strategy = GenerationType.IDENTITY)@Column(name = "user_id", unique = true, nullable = false)公共长 getUserId() {返回 this.userId;}public void setUserId(Long userId) {this.userId = 用户 ID；}私有集<UserCompetency>userCompetency = new HashSet(0);@OneToMany(fetch = FetchType.EAGER,cascade = {CascadeType.ALL},mappedBy = "user")公共集获取用户能力(){返回 this.userCompetencies;}public void setUserCompetencies(Set userCompetencies) {this.userCompetencies = userCompetencies;}}**能力**@实体@Table(name = "competency", schema = "public")@JsonIdentityInfo(生成器 = ObjectIdGenerators.IntSequenceGenerator.class,属性 = "能力 ID")公共类 Competency 实现了 java.io.Serializable {私人长期能力Id；私有集<UserCompetency>userCompetency = new HashSet(0);@Id @GeneratedValue(strategy = GenerationType.IDENTITY)@Column(name = "competency_id", unique = true, nullable = false)公共长 getCompetencyId() {返回 this.competencyId;}公共无效setCompetencyId(长能力Id){this.competencyId = 能力 ID；}@OneToMany(fetch = FetchType.LAZY，mappedBy = "能力")公共集获取用户能力(){返回 this.userCompetencies;}public void setUserCompetencies(Set userCompetencies) {this.userCompetencies = userCompetencies;}}用户能力 @Entity@Table(name = "user_competency", schema = "public")@JsonIdentityInfo(生成器 =ObjectIdGenerators.IntSequenceGenerator.class,属性 = "id")公共类 UserCompetency 实现 java.io.Serializable {私有 UserCompetencyId id；私人级别；私人用户用户；私人能力；@EmbeddedId@AttributeOverrides({@AttributeOverride(name = "competencyId", column = @Column(name = "competency_id", nullable = false)),@AttributeOverride(name = "userId", column = @Column(name = "user_id", nullable = false)) })公共 UserCompetencyId getId() {返回 this.id;}public void setId(UserCompetencyId id) {this.id = id;}@ManyToOne(fetch = FetchType.EAGER)@JoinColumn(name = "level_id")公共级别 getLevel() {返回 this.level;}public void setLevel(Level level) {this.level = 级别；}@ManyToOne(fetch = FetchType.EAGER)@JoinColumn(name = "user_id", nullable = false, insertable = false, updatable = false)公共用户 getUser() {返回 this.user;}公共无效设置用户(用户用户){this.user = 用户；}@ManyToOne(fetch = FetchType.EAGER,cascade=CascadeType.ALL)@JoinColumn(name = "competency_id", nullable = false, insertable = false, updatable = false)公共能力 getCompetency() {返回 this.competency;}公共无效setCompetency(能力能力){this.competency = 能力；}}UserCompetencyId@Embeddable公共类 UserCompetencyId 实现 java.io.Serializable {私人长期能力Id；私人长用户ID；公共 UserCompetencyId() {}public UserCompetencyId(长能力Id，长用户ID){this.competencyId = 能力 ID；this.userId = 用户 ID；}@Column(name = "competency_id", nullable = false)公共长 getCompetencyId() {返回 this.competencyId;}公共无效setCompetencyId(长能力Id){this.competencyId = 能力 ID；}@Column(name = "user_id", nullable = false)公共长 getUserId() {返回 this.userId;}public void setUserId(Long userId) {this.userId = 用户 ID；}公共布尔等于(对象其他){如果((这个==其他))返回真；如果((其他==空))返回假；if (!(other instanceof UserCompetencyId))返回假；UserCompetencyId castOther = (UserCompetencyId) other;返回 (this.getCompetencyId() == castOther.getCompetencyId()) &&(this.getUserId() == castOther.getUserId());}}UserCompetencyRepository 公共接口 UserCompetencyRepository 扩展 JpaRepository{}pom.</父母><属性><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><java.version>1.8</java.version></属性><依赖项><依赖><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></依赖><依赖><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></依赖><依赖><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-rest</artifactId></依赖><依赖><groupId>org.springframework.data</groupId><artifactId>spring-data-rest-hal-browser</artifactId></依赖><依赖><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-hateoas</artifactId></依赖><依赖><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-thymeleaf</artifactId></依赖><依赖><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></依赖><依赖><groupId>org.postgresql</groupId><artifactId>postgresql</artifactId><scope>运行时</scope></依赖><依赖><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></依赖><依赖><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-tomcat</artifactId><范围>提供</范围></依赖><依赖><groupId>com.h2database</groupId><artifactId>h2</artifactId><scope>运行时</scope></依赖><依赖><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><范围>测试</范围></依赖><依赖><groupId>org.springframework.restdocs</groupId><artifactId>spring-restdocs-mockmvc</artifactId><范围>测试</范围></依赖><依赖><groupId>org.springframework.boot</groupId><artifactId>spring-boot-configuration-processor</artifactId><optional>true</optional></依赖><依赖><groupId>org.springframework.boot</groupId><artifactId>spring-boot-configuration-processor</artifactId><optional>true</optional></依赖><依赖><groupId>org.springframework.data</groupId><artifactId>spring-data-rest-webmvc</artifactId></依赖></依赖项><构建><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></插件></plugins></build></项目>并且我想使用 URI 执行 GET，它返回我嵌入的对象并且无法获取对象属性的实际值 获取 如何获取需要 userId=8 帮助的 User 和 Competency 对象的属性值在实施建议的投影问题后仍未解决，这里是屏幕截图 解决方案 一种方法是使用投影，例如:@Projection(name = "edit" , types = Employee.class)公共接口 EditEmployeeProjection {字符串 getFirstName();String getLastName();设置获取项目()；}这样，项目列表将嵌入到 已编辑 2我使用的代码:能力.class@Entity@Table(name = "competency", schema = "public")@JsonIdentityInfo(生成器 = ObjectIdGenerators.IntSequenceGenerator.class,属性 = "能力 ID")公共类 Competency 实现了 java.io.Serializable {@Id @GeneratedValue(strategy = GenerationType.IDENTITY)@Column(name = "competency_id", unique = true, nullable = false)私人长期能力Id；@OneToMany(fetch = FetchType.LAZY，mappedBy = "能力")私人列表<UserCompetency>userCompetencies = new ArrayList();用户能力.class@Entity@Table(name = "user_competency", schema = "public")@JsonIdentityInfo(生成器 = ObjectIdGenerators.IntSequenceGenerator.class,属性 = "id")公共类 UserCompetency 实现 java.io.Serializable {@EmbeddedId@AttributeOverrides({@AttributeOverride(name = "competencyId", column = @Column(name = "competency_id", nullable = false)),@AttributeOverride(name = "userId", column = @Column(name = "user_id", nullable = false)) })私有 UserCompetencyId id；@ManyToOne(fetch = FetchType.EAGER)@JoinColumn(name = "user_id", nullable = false, insertable = false, updatable = false)私人用户用户；@ManyToOne(fetch = FetchType.EAGER,cascade = CascadeType.ALL)@JoinColumn(name = "competency_id", nullable = false, insertable = false, updatable = false)私人能力；UserCompetencyId.class@Embeddable公共类 UserCompetencyId 实现 java.io.Serializable {@Column(name = "competency_id", nullable = false)私人长期能力Id；@Column(name = "user_id", nullable = false)私人长用户ID；UserCompetencyRepository.class@RepositoryRestResource(excerptProjection = UserCompetencyProjection.class)公共接口 UserCompetencyRepository 扩展 JpaRepository{实现此后，在我的情况下，它无法显示所需的 jason [![在此处输入图像描述][2]][2]I am unable to retrieve embedded .I am using Spring boot ,spring data rest and spring JPA. I have 3 tables in data baseusercompetencyuser_competency (join/composite table with extra column)User@Entity@Table(name = "\"user\"", schema = "public")@JsonIdentityInfo( generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "userId")public class User implements java.io.Serializable { private Long userId; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "user_id", unique = true, nullable = false) public Long getUserId() { return this.userId; } public void setUserId(Long userId) { this.userId = userId; } private Set<UserCompetency> userCompetencies = new HashSet<UserCompetency>(0); @OneToMany(fetch = FetchType.EAGER,cascade = {CascadeType.ALL}, mappedBy = "user") public Set<UserCompetency> getUserCompetencies() { return this.userCompetencies; } public void setUserCompetencies(Set<UserCompetency> userCompetencies) { this.userCompetencies = userCompetencies; }}**Competency** @Entity @Table(name = "competency", schema = "public") @JsonIdentityInfo( generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "competencyId") public class Competency implements java.io.Serializable { private Long competencyId; private Set<UserCompetency> userCompetencies = new HashSet<UserCompetency>(0); @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "competency_id", unique = true, nullable = false) public Long getCompetencyId() { return this.competencyId; } public void setCompetencyId(Long competencyId) { this.competencyId = competencyId; } @OneToMany(fetch = FetchType.LAZY, mappedBy = "competency") public Set<UserCompetency> getUserCompetencies() { return this.userCompetencies; } public void setUserCompetencies(Set<UserCompetency> userCompetencies) { this.userCompetencies = userCompetencies; } }UserCompetency @Entity @Table(name = "user_competency", schema = "public") @JsonIdentityInfo( generator =ObjectIdGenerators.IntSequenceGenerator.class, property = "id") public class UserCompetency implements java.io.Serializable { private UserCompetencyId id; private Level level; private User user; private Competency competency; @EmbeddedId @AttributeOverrides({ @AttributeOverride(name = "competencyId", column = @Column(name = "competency_id", nullable = false)), @AttributeOverride(name = "userId", column = @Column(name = "user_id", nullable = false)) }) public UserCompetencyId getId() { return this.id; } public void setId(UserCompetencyId id) { this.id = id; } @ManyToOne(fetch = FetchType.EAGER) @JoinColumn(name = "level_id") public Level getLevel() { return this.level; } public void setLevel(Level level) { this.level = level; } @ManyToOne(fetch = FetchType.EAGER) @JoinColumn(name = "user_id", nullable = false, insertable = false, updatable = false) public User getUser() { return this.user; } public void setUser(User user) { this.user = user; } @ManyToOne(fetch = FetchType.EAGER,cascade=CascadeType.ALL) @JoinColumn(name = "competency_id", nullable = false, insertable = false, updatable = false) public Competency getCompetency() { return this.competency; } public void setCompetency(Competency competency) { this.competency = competency; }}UserCompetencyId@Embeddablepublic class UserCompetencyId implements java.io.Serializable { private Long competencyId; private Long userId; public UserCompetencyId() { } public UserCompetencyId(Long competencyId, Long userId) { this.competencyId = competencyId; this.userId = userId; } @Column(name = "competency_id", nullable = false) public Long getCompetencyId() { return this.competencyId; } public void setCompetencyId(Long competencyId) { this.competencyId = competencyId; } @Column(name = "user_id", nullable = false) public Long getUserId() { return this.userId; } public void setUserId(Long userId) { this.userId = userId; } public boolean equals(Object other) { if ((this == other)) return true; if ((other == null)) return false; if (!(other instanceof UserCompetencyId)) return false; UserCompetencyId castOther = (UserCompetencyId) other; return (this.getCompetencyId() == castOther.getCompetencyId()) && (this.getUserId() == castOther.getUserId()); }}UserCompetencyRepository public interface UserCompetencyRepository extends JpaRepository<UserCompetency, UserCompetencyId> {}pom.<?and I want to perform GET using URI,it return me embedded object and cannot get real value of objects attributesGET http://localhost:8080/userCompetenciesHow Can I get attribute values of User and Competency object where userId=8 Help is requiredAfter implementing suggested Projection Issue still not resolved and here is screen shot 解决方案 One way would be to use projections like for example:@Projection(name = "edit" , types = Employee.class)public interface EditEmployeeProjection { String getFirstName(); String getLastName(); Set<Project> getProjects();}With this the project list will be embedded in the result for http://localhost:8080/api/employee/1?projection=editProjections would be used automatically if you add excerptProjection to you repository like described here: How to expose a complete tree structure with Spring Data REST and HATEOAS?See for example here: https://shinesolutions.com/2015/04/15/spring-data-rest-and-projections/EDITEDIn you case a projection would look like:@Projection(name = "edit" , types = UserCompetency.class)public interface UserCompetencyProjection { User getUser(); Competency getCompetency();}With http://localhost:8080/userCompetencies?projection=edit you would then see wanted result.EDITED 2The code I used:Competency.class@Entity@Table(name = "competency", schema = "public")@JsonIdentityInfo( generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "competencyId")public class Competency implements java.io.Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "competency_id", unique = true, nullable = false) private Long competencyId; @OneToMany(fetch = FetchType.LAZY, mappedBy = "competency") private List<UserCompetency> userCompetencies = new ArrayList<>();UserCompetency.class@Entity@Table(name = "user_competency", schema = "public")@JsonIdentityInfo( generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "id")public class UserCompetency implements java.io.Serializable { @EmbeddedId @AttributeOverrides({ @AttributeOverride(name = "competencyId", column = @Column(name = "competency_id", nullable = false)), @AttributeOverride(name = "userId", column = @Column(name = "user_id", nullable = false)) }) private UserCompetencyId id; @ManyToOne(fetch = FetchType.EAGER) @JoinColumn(name = "user_id", nullable = false, insertable = false, updatable = false) private User user; @ManyToOne(fetch = FetchType.EAGER,cascade = CascadeType.ALL) @JoinColumn(name = "competency_id", nullable = false, insertable = false, updatable = false) private Competency competency;UserCompetencyId.class@Embeddablepublic class UserCompetencyId implements java.io.Serializable { @Column(name = "competency_id", nullable = false) private Long competencyId; @Column(name = "user_id", nullable = false) private Long userId;UserCompetencyRepository.class@RepositoryRestResource(excerptProjection = UserCompetencyProjection.class)public interface UserCompetencyRepository extends JpaRepository<UserCompetency, UserCompetencyId> {After Implementing This ,In my case its not working to show desired jason [![enter image description here][2]][2] 这篇关于在@ManytoMany 关系和具有额外列的查找表的情况下，无法检索 Spring HATEOAS 嵌入的资源对象的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！