org.apache.beam.sdk.io.cassandra

Interface Mapper<T>

@Experimental(value=SOURCE_SINK)
public interface Mapper<T>

This interface allows you to implement a custom mapper to read and persist elements from/to Cassandra.

To Implement a custom mapper you need to: 1) Create an implementation of Mapper. 2) Create a SerializableFunction that instantiates the Mapper for a given Session, for an example see DefaultObjectMapperFactory). 3) Pass this function to CassandraIO.Read.withMapperFactoryFn(SerializableFunction) in the CassandraIO builder.
Example:

 SerializableFunction<Session, Mapper> factory = new MyCustomFactory();
 pipeline
    .apply(...)
    .apply(CassandraIO.<>read()
        .withMapperFactoryFn(factory));
 

Method Summary

Modifier and Type	Method and Description
java.util.concurrent.Future<java.lang.Void>	deleteAsync(T entity) This method is called for each delete event.
java.util.Iterator<T>	map(com.datastax.driver.core.ResultSet resultSet) This method is called when reading data from Cassandra.
java.util.concurrent.Future<java.lang.Void>	saveAsync(T entity) This method is called for each save event.

Method Detail

map

java.util.Iterator<T> map(com.datastax.driver.core.ResultSet resultSet)

This method is called when reading data from Cassandra. It should map a ResultSet into the corresponding Java objects.

Parameters:

resultSet - A resultset containing rows.

Returns:

An iterator containing the objects that you want to provide to your downstream pipeline.

deleteAsync

java.util.concurrent.Future<java.lang.Void> deleteAsync(T entity)

This method is called for each delete event. The input argument is the Object that should be deleted in Cassandra. The return value should be a Future that completes when the delete action is completed.

Parameters:

entity - Entity to be deleted.

saveAsync

java.util.concurrent.Future<java.lang.Void> saveAsync(T entity)

This method is called for each save event. The input argument is the Object that should be saved or updated in Cassandra. The return value should be a future that completes when the save action is completed.

Parameters:

entity - Entity to be saved.