Question

我正在Mongo上使用spring数据休息来公开具有多个子类型的类。当我这样做时，HATEOAS将根据实际的实例化类型而不是通用基本类型对结果进行划分。这会导致链接不正确，并且由于分页是混合类型列表，因此使分页无效。

我尝试将@Relation标记显式添加到所有涉及的类中，这似乎完全没有影响。无论有没有，我都能得到相同的结果。

我正在使用带有Spring-boot-starter-data-rest和spring-cloud-dependencies Greenwich.SR1的spring boot依赖2.1.8.RELEASE

基类：

@Relation(collectionRelation = "notifications", value="notifications")
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "notificationType")
@JsonSubTypes({
        @JsonSubTypes.Type(value = ModelNotification.class, name = Notification.MODEL_NOTIFICATION),
        @JsonSubTypes.Type(value = BasicNotification.class, name = Notification.BASIC_NOTIFICATION)
})
public class Notification extends UUIDEntity implements Serializable {
    private static final long serialVersionUID = 8199210081144334378L;

    public static final String MODEL_NOTIFICATION = "MODEL_NOTIFICATION";
    public static final String BASIC_NOTIFICATION = "BASIC_NOTIFICATION";

    public enum Severity {
        TRACE,
        DEBUG,
        INFO,
        WARN,
        ERROR,
        FATAL
    }

    public Notification() {
        this.notificationType = BASIC_NOTIFICATION;
    }

    @JsonProperty("notificationType")
    private String notificationType;

    @JsonProperty("createdDate")
    @CreatedDate
    private Instant createdDate;

    @JsonProperty("lastModifiedDate")
    @LastModifiedDate
    private Instant lastModifiedDate;

    @JsonProperty("createdBy")
    @CreatedBy
    private String createdBy;

    @JsonProperty("lastModifiedBy")
    @LastModifiedBy
    private String lastModifiedBy;

    @JsonProperty("severity")
    private Severity severity;

    @JsonProperty("message")
    private String message;

没有其他成员版本：

@Relation(collectionRelation = "notifications", value="notifications")
public class BasicNotification extends Notification implements Serializable {
    private static final long serialVersionUID = 8063077545983014320L;
}

扩展名：

@Relation(collectionRelation = "notifications", value="notifications")
public class ModelNotification extends Notification implements Serializable {
    private static final long serialVersionUID = 3700576594274374440L;

    @JsonProperty("storedModel")
    private StoredModel storedModel;

    public ModelNotification() {
        super();
        this.setNotificationType(Notification.MODEL_NOTIFICATION);
    }

我希望给定添加@Relation标记后，所有结果都将显示在通知下，这是spring数据剩余端点的正确URL。请注意，所有端点均正常工作，但是仅HATEOAS内容不正确，并且捆绑会产生问题。在以下位置访问：/ api / notifications

我回来了：

{
  "_embedded" : {
    "modelNotifications" : [ {
      "notificationType" : "MODEL_NOTIFICATION",
      "createdDate" : "2019-10-02T15:53:42.127Z",
      "lastModifiedDate" : "2019-10-02T15:53:42.127Z",
...
[SNIP FOR BREVITY]
...
        } ]
      },
      "_links" : {
        "self" : {
          "href" : "http://fastscore:8088/api/modelNotification/ef81c342-29d3-48fb-bab3-d416e80bc5f6"
        },
        "modelNotification" : {
          "href" : "http://fastscore:8088/api/modelNotification/ef81c342-29d3-48fb-bab3-d416e80bc5f6"
        }
      }
    } ],
    "notifications" : [ {
      "notificationType" : "BASIC_NOTIFICATION",
      "createdDate" : "2019-10-02T15:52:10.261Z",
      "lastModifiedDate" : "2019-10-02T15:52:10.261Z",
      "createdBy" : "anonymousUser",
      "lastModifiedBy" : "anonymousUser",
      "severity" : "INFO",
      "message" : "Interval Process Completed Successfully",
      "_links" : {
        "self" : {
          "href" : "http://fastscore:8088/api/notifications/93fa5d6b-1457-4fa6-976c-cfdddc422976"
        },
        "notification" : {
          "href" : "http://fastscore:8088/api/notifications/93fa5d6b-1457-4fa6-976c-cfdddc422976"
        }
      }

...
[SNIP]
...
    }, 
  },
  "_links" : {
    "self" : {
      "href" : "http://fastscore:8088/api/notifications{?page,size,sort}",
      "templated" : true
    },
    "profile" : {
      "href" : "http://fastscore:8088/api/profile/notifications"
    },
    "search" : {
      "href" : "http://fastscore:8088/api/notifications/search"
    }
  },
  "page" : {
    "size" : 20,
    "totalElements" : 4,
    "totalPages" : 1,
    "number" : 0
  }
}

这显然是不正确的，因为modelNotifications不是spring数据剩余端点。另外，这将使分页变得无用，好像我有大量的通知，分页仅适用于那些通知，即使我只有一个，我也每次都会收到modelNotifications。因此，在第二页上，我将收到第二页的通知，但是即使我只有一个条目，第二页上仍然有modelNotifications。

这种类型的渲染使HATEOAS支持无法与spring数据剩余一起使用。

Answer 1

整天玩完之后，@ Relation标记似乎在这种情况下根本不起作用。因此，我决定寻找解决方法。我所做的是实现一个RelProvider来正确检查继承，并返回正确的集合名称：

@Order(Ordered.HIGHEST_PRECEDENCE)
@Component
public class NotificationRelProvider implements RelProvider {
    @Override
    public String getItemResourceRelFor(Class<?> aClass) {
        return "notification";
    }

    @Override
    public String getCollectionResourceRelFor(Class<?> aClass) {
        return "notifications";
    }

    @Override
    public boolean supports(Class<?> aClass) {
        return Notification.class.isAssignableFrom(aClass);
    }
}

然后我按照文档中的说明标记了spring数据剩余存储库：

@ExposesResourceFor(Notification.class)
@RepositoryRestResource()
public interface NotificationRepository extends MongoRepository<Notification, UUID> {
    List<Notification> findAllBySeverityOrderByCreatedDateDesc(@Param("severity") Notification.Severity severity);
}

完成此操作后，我现在得到以下正确和预期的行为：

 "_embedded" : {
    "notifications" : [ {
      "notificationType" : "BASIC_NOTIFICATION",
      "createdDate" : "2019-10-02T23:06:16.802Z",
      "lastModifiedDate" : "2019-10-02T23:06:16.802Z",
      "createdBy" : "anonymousUser",
      "lastModifiedBy" : "anonymousUser",
      "severity" : "INFO",
      "message" : "Interval Process Completed Successfully",
      "_links" : {
        "self" : {
          "href" : "http://fastscore:8088/api/notifications/eb214276-2880-43e0-8c7f-1519b1e7e343"
        },
        "notification" : {
          "href" : "http://fastscore:8088/api/notifications/eb214276-2880-43e0-8c7f-1519b1e7e343"
        }
      }
    }, {
      "notificationType" : "MODEL_NOTIFICATION",
      "createdDate" : "2019-10-02T23:07:32.649Z",
      "lastModifiedDate" : "2019-10-02T23:07:32.649Z",
      "createdBy" : "anonymousUser",
      "lastModifiedBy" : "anonymousUser",
....

因此，这可以解决原始错误，但这是一种手动过程，而不仅仅是使用文档中所述的注释。不幸的是，这意味着我必须为存储库中的每个基类创建这些RelProvider类之一，但是至少它可以工作并且可用于分页。

如果使用JsonSubTypes，则HATEOAS链接错误

1 个答案: