[英]Cassandra CodecNotFoundException: Codec not found for requested operation
我有一個枚舉字段,我想映射到cassandra中的列
public enum MyEnum {
Aa,
Bb,
Cc,
}
這是我如何注冊它
CodecRegistry myCodecRegistry = new CodecRegistry();
myCodecRegistry.register(new EnumOrdinalCodec<MyEnum>(MyEnum.class));
cluster = Cluster.builder().addContactPoint(cassandraHosts).withPort(cassandraPort).withCodecRegistry(myCodecRegistry).build();
我能夠連接到cassandra就好了。 這是模型類的片段
public class MyModel
{
@PartitionKey
@Column(name="id")
private String id;
@ClusteringColumn
@Column(name="name")
private String name = "";
@Column(name="enum")
private MyEnum enum;
public MyModel(String i, String n)
{
id=i;
name=n
enum=MyEnum.Aa;
}
}
這是我如何使用CQL創建表
CREATE TABLE IF NOT EXISTS
tab
(
name varchar ,
id varchar,
enum varchar,
PRIMARY KEY ((id), name));
最后,我有我的映射代碼
manager = new MappingManager(session);
mapper = manager.mapper(MyModel.class);
accessor = manager.createAccessor(MyAccessor.class);
這是MyAccessor
@Accessor
public interface MyAccessor{
@Query("SELECT * FROM case WHERE id=? and name=? ALLOW FILTERING;")
MyModel readByIdAndName(String id,String name);
}
所以當我嘗試執行
MyModel m = new MyModel("asdasf","qw");
mapper.save(m);
我明白了
com.datastax.driver.core.exceptions.CodecNotFoundException: Codec not found for requested operation: [varchar <-> my.pack.MyEnum]
at com.datastax.driver.core.exceptions.CodecNotFoundException.copy(CodecNotFoundException.java:56)
at com.datastax.driver.core.exceptions.CodecNotFoundException.copy(CodecNotFoundException.java:25)
at com.datastax.driver.mapping.DriverThrowables.propagateCause(DriverThrowables.java:41)
at com.datastax.driver.mapping.Mapper.save(Mapper.java:289)
我究竟做錯了什么?
EnumOrdinalCodec僅用於在int < - > Enum之間進行映射。 由於您的Enum基於字符串,因此請使用EnumNameCodec
類。 這兩個編解碼器類的Javadoc如下所示。 希望能幫助到你。
EnumNameCodec
將Enum實例序列化為CQL varchars的編解碼器,表示由Enum.name()返回的程序名。
EnumOrdinalCodec
將Enum實例序列化為CQL整數的編解碼器,表示由Enum.ordinal()返回的序數值。
鏈接到Javadoc
更改代碼如下:
/* This is not required
CodecRegistry myCodecRegistry = new CodecRegistry();
myCodecRegistry.register(new EnumOrdinalCodec<MyEnum>(MyEnum.class));
*/
cluster = Cluster
.builder()
.addContactPoint(cassandraHosts)
.withPort(cassandraPort)
.build();
class MyEnumCodec: EnumOrdinalCodec<MyEnum> { MyEnumCodec() { super(MyEnum.class) } }
public class MyModel
{
@PartitionKey
@Column(name="id")
private String id;
@ClusteringColumn
@Column(name="name")
private String name = "";
@Column(name="enum", codec = MyEnumCodec.class)
private MyEnum enum;
public MyModel(String i, String n)
{
id=i;
name=n
enum=MyEnum.Aa;
}
}
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