Spring Boot JPA 规范-arg-resolver 已加入表答案

【问题标题】：Spring Boot JPA specification-arg-resolver JOINED TableSpring Boot JPA 规范-arg-resolver 已加入表
【发布时间】：2021-06-04 15:57:29
【问题描述】：

我正在尝试使用 REST 查询过滤器接口编写 Spring Boot 应用程序。

我想要达到的目标：localhost:8080/persons/search?age=42&city=Berlin&skilltype=Sport

基本类型（String、Int、...）的正常过滤已经成功运行。我在过滤另一个表的属性时遇到问题。

@Entity

public class Person {

  @Id
  @Column(name = "id", nullable = false)
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private long id;

  @Column(name = "age")
  private Integer age;

  @Column(name = "city")
  private String city;

  @Column(name = "skills")
  @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
  @JoinColumn(name = "person_id")
  private Set<Skill> skills;

@Entity
public class Skill {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private long id;

  @Column(name = "name", nullable = false)
  private String name;

  @Column(name = "type", nullable = false)
  private String type;
}

控制器

import net.kaczmarzyk.spring.data.jpa.domain.*;
import net.kaczmarzyk.spring.data.jpa.web.annotation.And;
import net.kaczmarzyk.spring.data.jpa.web.annotation.Join;

  @GetMapping(value = "/persons/search", produces = MediaType.APPLICATION_JSON_VALUE)
  public ResponseEntity<List<Person>> getPersonBySpecification(
      @Join(path = "skills", alias = "s")
          @And({
            @Spec(path = "id", params = "id", spec = Equal.class),
            @Spec(path = "name", params = "name", spec = EqualIgnoreCase.class),
            @Spec(path = "age", params = "age", spec = Equal.class),
            @Spec(path = "city", params = "city", spec = Like.class),
            @Spec(path = "zipCode", params = "zipCode", spec = In.class),
            @Spec(path = "s.name", params = "skillname", spec = In.class),
            @Spec(path = "s.type", params = "skilltype", spec = In.class),
          })
          Specification<Person> spec) {
    return ResponseEntity.ok().body(this.personService.getPersonBySpecification(spec));
  }

异常java.lang.NullPointerException: Cannot invoke "Object.getClass()" because "cause" is null

非常感谢您的任何建议！

【问题讨论】：

标签： java spring spring-boot hibernate jpa

【解决方案1】：

这个问题花费了我很多时间，尤其是神经！

     <dependency>
            <groupId>net.kaczmarzyk</groupId>
            <artifactId>specification-arg-resolver</artifactId>
            <version>2.6.2</version>
        </dependency>

不兼容 java 16！

我能够在 Java8 Docker 容器中成功运行上述代码。

#
# Build stage
#
FROM maven:3.6.0-jdk-11-slim AS build
COPY src /home/app/src
COPY pom.xml /home/app
RUN mvn -f /home/app/pom.xml clean package

#
# Package stage
#
FROM openjdk:8-jre-slim
COPY --from=build /home/app/target/app-0.0.1-SNAPSHOT.jar /usr/local/lib/app.jar
EXPOSE 8080
ENTRYPOINT ["java","-jar","/usr/local/lib/app.jar"]

【讨论】：