Question

我有以下列系列：

@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？

Answer 1

有两个选项可以用Spring Data Cassandra表示复合键：

在域类型中使用@PrimaryKeyColumn（与您一样）。
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，不能仅将LocalDateTime声明为id。如果您想在域类型中坚持@PrimaryKeyColumn，请使用MapId作为ID类型：

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

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

    @PrimaryKeyColumn(name = "date_requested", ordinal = 1, type = PrimaryKeyType.CLUSTERED,
            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", ordinal = 0,
            type = PrimaryKeyType.PARTITIONED) 
    private LocalDate dayRequested;

    @PrimaryKeyColumn(name = "date_requested", ordinal = 1, type = PrimaryKeyType.CLUSTERED,
            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(…))

Answer 2

只需在RequestEventRepository中创建其他查询方法。

@Repository
public interface RequestEventRepository extends CrudRepository<RequestEvent, LocalDateTime> {
    List<RequestEvent> findAllByDayRequested(LocalDateTime day);
    RequestEvent findOneByDayRequestedAndDateRequested(LocalDateTime day, LocalDateTime localDateTime);
}

Answer 3

如果要按键类的分区键进行搜索那么您需要在存储库接口中添加新方法新方法的名称将遵循此约定

// {MethodName} {PrimaryKeyClassName} {PrimaryKeyColumn}

示例：

@PrimaryKeyClass
public class UserKey implements Serializable {
    private static final long serialVersionUID = 1L;
    @PrimaryKeyColumn(name = "email", type = PrimaryKeyType.PARTITIONED)
    private String email;
    @PrimaryKeyColumn(name = "firstname", ordinal = 0, type = PrimaryKeyType.CLUSTERED, ordering = Ordering.DESCENDING)
    private String firstName;
    @PrimaryKeyColumn(name = "lastname", ordinal = 1, type = PrimaryKeyType.CLUSTERED, ordering = Ordering.ASCENDING)
    private String lastName;
    //equals and hashcode methods
}

然后方法名称为

User findByUserKeyEmail(String email);

Answer 4

我想补充一下，spring-data-cassandra的最新版本包括一个新的存储库接口，从而无需在主存储库接口中指定Primary Keys或MapId。

使用MapIdCassandraRepository代替CassandraRepository：

public interface MyTableRepository extends MapIdCassandraRepository<MyTable> {
}

如您在上面的代码中所见，扩展MapIdCassandraRepository接口仅需要指示所需的表。

参考： https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/#cassandra.migration

Spring Data Cassandra：如何使用复合键查询表？

4 个答案: