java – Spring Data Cassandra：如何使用复合键查询表？

发布时间：2020-12-15 04:39:13 所属栏目：Java 来源：网络整理

导读：我有以下列族： @Table(value = "request_event")public class RequestEvent { @PrimaryKeyColumn(name = "day_requested",ordinal = 0,type = PrimaryKeyType.PARTITIONED) private LocalDate dayRequested; @PrimaryKeyColumn(name = "date_requested",ord

我有以下列族：

@Table(value = "request_event")
public class RequestEvent {

    @PrimaryKeyColumn(name = "day_requested",ordinal = 0,type = PrimaryKeyType.PARTITIONED)
    private LocalDate dayRequested;

    @PrimaryKeyColumn(name = "date_requested",ordinal = 1,type = PrimaryKeyType.CLUSTERED,ordering = Ordering.DESCENDING)
    private LocalDateTime dateRequested;

    ...
}

由存储库存储和访问：

@Repository
public interface RequestEventRepository extends CrudRepository<RequestEvent,LocalDateTime> {
}

不幸的是,requestEventRepository.findOne(localDate)抛出一个异常,可能是因为它返回了多个结果.我怎样才能解决这个问题？此外,如何检索特定日期的所有结果？

解决方法

您有两个选项来表示Spring Data Cassandra的复合键：

>在域类型中使用@PrimaryKeyColumn(就像你一样).
>使用@PrimaryKeyClass表示主键并将其嵌入域类型中.

Spring Data存储库接受单个ID类型.因此,不可能只将LocalDateTime声明为id.如果要在域类型中坚持@PrimaryKeyColumn,请使用MapId作为id类型：

@Table(value = "request_event")
public class RequestEvent {

    @PrimaryKeyColumn(name = "day_requested",type = PrimaryKeyType.PARTITIONED) 
    private LocalDate dayRequested;

    @PrimaryKeyColumn(name = "date_requested",ordering = Ordering.DESCENDING) 
    private LocalDateTime dateRequested;

}

public interface RequestEventRepository extends CrudRepository<RequestEvent,MapId> {}

MapId mapId = BasicMapId.id("dayRequested",…).with("dateRequested",…);

RequestEvent loaded = eventRepository.findOne(mapId);

如果您决定将主键表示为值对象,则需要稍微调整域类型：

@PrimaryKeyClass
public class Key implements Serializable {

    @PrimaryKeyColumn(name = "day_requested",ordering = Ordering.DESCENDING) 
    private LocalDateTime dateRequested;

}

@Table(value = "request_event")
public class RequestEvent {

    @PrimaryKey 
    private Key key;

}

public interface RequestEventRepository extends CrudRepository<RequestEvent,Key> {}

eventRepository.findOne(new Key(…))

（编辑：李大同）

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