cassandra trigger on composite blob key - cassandra

Question

I use Cassandra 2.1.9 and have table like
create table "Keyspace1"."Standard4" ( id blob, user_name blob, data blob, primary key(id, user_name));
and I follow the post in Cassandra Sample Trigger Code to get inserted value and do trigger code like
public class InvertedIndex implements ITrigger
{
private static final Logger logger = LoggerFactory.getLogger(InvertedIndex.class);
public Collection augment(ByteBuffer key, ColumnFamily update)
{
CFMetaData cfm = update.metadata();
ByteBuffer id_bb = key;
String id_Value = new String(id_bb.array());
Iterator col_itr=update.iterator();
Cell username_col=(Cell)col_itr.next();
ByteBuffer username_bb=CompositeType.extractComponent(username_col.name().collectionElement(),0);
String username_Value = new String(username_bb.array());
Cell data_col=(Cell)col_itr.next();
ByteBuffer data_bb=BytesType.instance.compose(data_col.value());
String data_Value = new String(data_bb.array());
logger.info(" id --> "+id_Value);
logger.info(" username-->"+username_Value);
logger.info(" data ---> "+data_Value);
return null;
}
}
I tried insert into "Keyspace1"."Standard4" (id, user_name, data) values (textAsBlob('id1'), textAsBlob('user_name1'), textAsBlob('data1'));
and got run time exception in ByteBuffer username_bb=CompositeType.extractComponent(username_col.name().collectionElement(),0);
Caused by: java.lang.NullPointerException: null
at org.apache.cassandra.db.marshal.CompositeType.extractComponent(CompositeType.java:191) ~[apache-cassandra-2.1.9.jar:2.1.9]
at org.apache.cassandra.triggers.InvertedIndex.augment(InvertedIndex.java:52) ~[na:na]
at org.apache.cassandra.triggers.TriggerExecutor.executeInternal(TriggerExecutor.java:223) ~[apache-cassandra-2.1.9.jar:2.1.9]
... 17 common frames omitted
Can anybody tell me how to correct?

Answer 1

You are trying to show all the inserted column name and value right ?
Here is the code:
#Override
public Collection<Mutation> augment(ByteBuffer key, ColumnFamily update) {
CFMetaData cfm = update.metadata();
System.out.println("key => " + ByteBufferUtil.toInt(key));
for (Cell cell : update) {
if (cell.value().remaining() > 0) {
try {
String name = cfm.comparator.getString(cell.name());
String value = cfm.getValueValidator(cell.name()).getString(cell.value());
System.out.println("Column Name => " + name + " Value => " + value);
} catch (Exception e) {
System.out.println("Exception : " + e.getMessage());
}
}
}
return null;
}