问使用Spring的JsonMappingException :从映射的列表中删除@Id时选择错误的序列化程序
EN

Stack Overflow用户

提问于 2017-07-18 06:07:13

回答 1查看 703关注 0票数 0

我已经创建了一个gitlab项目(网址)，在这里我希望使用Spring来持久化并公开一些传感器数据。在使用HAL浏览器进行测试时，坚持使用PostgreSQL DB没有问题，但SensorReading GET给我带来了一些麻烦：

无法写入JSON:不能将com.fasterxml.jackson.databind.JsonMappingException:转换为java.lang.Double；嵌套异常是java.lang.Double，不能将java.lang.Integer转换为java.lang.Double(通过引用链: org.springframework.hateoas.Resources\"_embedded\">java.util.Collections$UnmodifiableMap\"sensorReadings\">java.util.ArrayList>org.springframework.data.rest.webmvc.json.PersistentEntityJackson2Module$PersistentEntityResourceSerializer$1\"content\"->net.smurfz.kado.models.SensorReading\"sensorId\") )

my @Entity-class (net.smurfz.kado.models.SensorReading)中的代码：

@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-class (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，我尊敬的同事发现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;