java - 使用 Spring Data REST 的 JsonMappingException : Selects wrong serializer when @Id is removed from the list that that is being mapped

Question

我创建了一个 project on gitlab(url)我想使用 Spring Data REST 来保存和公开一些传感器数据。当使用 HAL 浏览器进行测试时，持久化到 PostgreSQL DB 没有问题，但 SensorReading GET 给我带来了一些麻烦:

Could not write JSON: java.lang.Integer cannot be cast to java.lang.Double; nested exception is com.fasterxml.jackson.databind.JsonMappingException: java.lang.Integer cannot be cast to java.lang.Double (through reference chain: org.springframework.hateoas.Resources[\"_embedded\"]>java.util.Collections$UnmodifiableMap[\"sensorReadings\"]>java.util.ArrayList[0]>org.springframework.data.rest.webmvc.json.PersistentEntityJackson2Module$PersistentEntityResourceSerializer$1[\"content\"]->net.smurfz.kado.models.SensorReading[\"sensorId\"])

我的@Entity类中的代码(net.smurfz.kado.models.SensorReading):

@Entity
public class SensorReading {

    @Id
    @org.springframework.data.annotation.Id
    @SequenceGenerator(name = "sensor_reading_id_seq",
            sequenceName = "sensor_reading_id_seq",
            allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE,
            generator = "sensor_reading_id_seq")
    @Column(updatable = false)
    private Integer id;

    @NotNull
    private Integer sensorId;

    @NotNull
    private double reading;

    @Column(name = "created_date")
    @ReadOnlyProperty
    private Date created;

    public SensorReading() {
    }

    public SensorReading(Integer sensorId, double reading) {
        this.sensorId = sensorId;
        this.reading = reading;
    }

    public Integer getId() {
        return id;
    }

    public Integer getSensorId() {
        return sensorId;
    }

    public void setSensorId(Integer sensorId) {
        this.sensorId = sensorId;
    }

    public double getReading() {
        return reading;
    }

    public void setReading(double reading) {
        this.reading = reading;
    }

    public Date getCreated() {
        return created;
    }

    @PrePersist
    protected void onCreate() {
        created = new Date();
    }
}

和我的@RepositoryRestResource类(net.smurfz.kado.repositories.SensorReadingRepository):

@RepositoryRestResource
public interface SensorReadingRepository extends CrudRepository<SensorReading, Integer> {
    List<SensorReading> findTop30BySensorIdOrderByCreatedDesc(Integer sensorId);
    Long countAllBySensorId(Integer sensorId);
    SensorReading findFirstBySensorIdOrderByCreatedDesc(Integer sensorId);
    Page<SensorReading> findAllBySensorId(Integer sensorId, Pageable pageable);
}

现在，我尊敬的同事设法找到的快速解决办法是移动:

        @Id
        @org.springframework.data.annotation.Id
        @SequenceGenerator(name = "sensor_reading_id_seq",
                sequenceName = "sensor_reading_id_seq",
                allocationSize = 1)
        @GeneratedValue(strategy = GenerationType.SEQUENCE,
                generator = "sensor_reading_id_seq")
        @Column(updatable = false)
        private Integer id;

在所有其他字段声明下。

当 BeanSerializerFactory 类尝试定义要使用的序列化器时，会发生此错误。我的工作理论是，它最初识别 4 个字段(4 个列表)，然后过滤掉不被序列化的 id(3 个列表)，但决定使用第二个列表中第一个列表中的索引 (1-3) ，导致 Integer 字段获得下面定义的 double 字段的序列化器。

这是一个不需要的肮脏黑客，因为我真的不知道这可能会影响我想知道的其他事情:

a)为什么会发生这种情况？

b)应该采取什么不同的措施来避免此错误？

上面的 URL 直接链接到实现 id-fix 之前的提交。

Answer 1

引用@Damien 的评论:

I didnt no - based on this jira - github.com/spring-projects/spring-boot/issues/9756. Changing the version to 2.0.0.BUILD-SNAPSHOT resolves the issue. – Damien

springBootVersion = '2.0.0.BUILD-SNAPSHOT' 解决了这个问题。