Spring Data Cassandra：如何使用复合键查询表？

Question

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？

Answer 1

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);
}

Answer 2

您有两个选项可以用 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 数据存储库接受单一 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使用 @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);

如果您决定将您的主键表示为一个值对象，那么您需要稍微调整您的域类型：

@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 3

如果你想按你的键的分区键搜索class 那么你需要在Respository Interface中添加一个新方法新方法名称将遵循此约定

//{方法名}{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
}

那么方法名就是

User findByUserKeyEmail(String email);

Answer 4

我只想补充一点，最新版本的 spring-data-cassandra 包含一个新的存储库界面，无需在主存储库界面中指定 Primary Keys 或 MapId。

使用MapIdCassandraRepository代替CassandraRepository:

public interface MyTableRepository extends MapIdCassandraRepository<MyTable> {
}

在上面的代码中可以看到，扩展MapIdCassandraRepository接口只需要指明你想要的Table。

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？

Spring Data Cassandra: How to query tables with compound keys?

java

spring

cassandra

spring-data

spring-data-cassandra