Spring Data Cassandra:如何使用复合键查询表?
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【中文标题】Spring Data Cassandra:如何使用复合键查询表?【英文标题】:Spring Data Cassandra: How to query tables with compound keys? 【发布时间】:2017-11-12 03:02:17 【问题描述】: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)
正在抛出异常,可能是因为它返回了多个结果。我怎样才能解决这个问题?另外,如何检索特定日期的所有结果?
【问题讨论】:
【参考方案1】:我想补充一点,最新版本的 spring-data-cassandra 包含一个新的存储库接口,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>
从上面的代码可以看出,扩展MapIdCassandraRepository
接口只需要指明你想要的Table即可。
参考: https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/#cassandra.migration
【讨论】:
【参考方案2】:如果你想按你的键类的分区键搜索 那么你需要在 Respository Interface 添加一个新方法 新方法名称将遵循此约定
//方法名PrimaryKeyClassNamePrimaryKeyColumn
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
那么方法名就是
User findByUserKeyEmail(String email);
【讨论】:
【参考方案3】:您有两个选项可以使用 Spring Data Cassandra 表示复合键:
-
在域类型中使用
@PrimaryKeyColumn
(就像您所做的那样)。
使用@PrimaryKeyClass
表示主键并将其嵌入到域类型中。
Spring Data 存储库接受单个 ID
类型。因此,不能只将LocalDateTime
声明为 id。如果你想在域类型中坚持@PrimaryKeyColumn
,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(…))
【讨论】:
查询方法名中需要包含属性路径。对于上面的示例,它将是findAllByKeyDayRequested(…)
。
而且Spring还提供了MapIdCassandraRepository
。【参考方案4】:
只需在 RequestEventRepository 中创建额外的查询方法。
@Repository
public interface RequestEventRepository extends CrudRepository<RequestEvent, LocalDateTime>
List<RequestEvent> findAllByDayRequested(LocalDateTime day);
RequestEvent findOneByDayRequestedAndDateRequested(LocalDateTime day, LocalDateTime localDateTime);
【讨论】:
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