无法POST一个集合

Question

我有一个简单的实体,映射了一个集合.

@Entity
public class Appointment Identifiable<Integer>   {  

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @JsonIgnore
    private Integer id;

    @Column(name="TRAK_NBR")
    private String trackNumber;

    @OneToMany(fetch =FetchType.EAGER, cascade= CascadeType.ALL)
    @JoinColumn(name="CNSM_APT_VER_WRK_I", nullable = false)
    private Set<Product> products = new HashSet<Product>();
}

@Entity
public class Product implements Identifiable<Integer> {

    @Id
    @Column(name = "CNSM_PRD_VER_WRK_I")
    @GeneratedValue(strategy = GenerationType.AUTO)
    @JsonIgnore
    private Integer id;

    @Column(name = "PRD_MDL_NBR")
    private String model;

    @Column(name = "PRD_SPEC_DSC")
    private String description;
}

在我的应用程序中,我只包含一个PagingAndSortingRepository for Appointment.我可以使用以下有效负载调用POST命令.

{
  "trackNumber" : "XYZ123",
  "products": [
    {"model" : "MODEL",
     "description" : "NAME"
    }]
}

当我为Product添加PagingAndSortingRepository并尝试相同的POST时,我收到以下错误消息.

{
  "cause" : {
    "cause" : {
      "cause" : null,
      "message" : null
    },
    "message" : "(was java.lang.NullPointerException) (through reference chain: com..model.Appointment[\"products\"])"
  },
  "message" : "Could not read JSON: (was java.lang.NullPointerException) (through reference chain: com.model.Appointment[\"products\"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: com.model.AppointmentVerification[\"products\"])"
}

My GET payload with both Repositories returns this.  This is my desired format.  The link to products should be included

{
  "trackNumber" : "XYZ123", 
  "_links" : {
    "self" : {
      "href" : "http://localhost:8080/consumerappointment/appointments/70"
    },
    "products" : {
      "href" : "http://localhost:8080/consumerappointment/appointments/70/products"
  }
}

只有Appointment存储库,我得到以下有效负载,并可以发布产品列表.

{
  "trackNumber" : "XYZ123",
  "products" : [ {
    "model" : "MODEL",
    "description" : "NAME",
  } ],
  "_links" : {
    "self" : {
      "href" : "http://localhost:8080/consumerappointment/appointments/1"
    }
  }
}

Answer 1

让我们退后一步，确保您了解这里发生的情况：如果检测到存储库，Spring Data REST 会公开一组专用资源，用于管理存储库通过 HTTP 处理的聚合。因此，如果您有多个彼此相关的实体的存储库，则该关系将表示为链接。这就是为什么AppointmentRepository在products创建ProductRepository.

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如果要将两个存储库公开为资源，则需要Product在有效负载中传递实例的 URI，以便POST创建Appointment. 这意味着，不要发布此内容：

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{ "trackNumber" : "XYZ123",\n  "products": [\n    { "model" : "MODEL",\n      "description" : "NAME"\n    }\n  ]\n}\n

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你会创建Product第一个：

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POST /products\n{ "model" : "MODEL",\n  "description" : "NAME" }\n\n201 Created\nLocation: \xe2\x80\xa6/products/4711\n

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然后将产品的ID交给payload Appointment：

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{ "trackNumber" : "XYZ123",\n  "products": [ "\xe2\x80\xa6/products/4711" ]}\n

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如果您不想要任何这些（Product首先不暴露任何资源，请使用@RepositoryRestResource(exported = false)on PersonRepository。这仍然会为您留下为存储库创建的 bean 实例，但不会导出任何资源，并且为Appointments 暴露的资源返回到内联 相关Product.

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