org.springframework.data.cassandra.core.cql

Interface ResultSetExtractor<T>

All Known Implementing Classes:

CqlTemplate.RowCallbackHandlerResultSetExtractor, RowMapperResultSetExtractor

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface ResultSetExtractor<T>

Callback interface used by CqlTemplate's query methods. Implementations of this interface perform the actual work of extracting results from a ResultSet, but don't need to worry about exception handling. DriverExceptions will be caught and handled by the calling CqlTemplate.

This interface is mainly used within the CQL framework itself. A RowMapper is usually a simpler choice for ResultSet processing, mapping one result object per row instead of one result object for the entire ResultSet.

Note: In contrast to a RowCallbackHandler, a ResultSetExtractor object is typically stateless and thus reusable, as long as it doesn't access stateful resources or keep result state within the object.

Author:

Matthew T. Adams, Mark Paluch

See Also:

AsyncCqlTemplate, CqlTemplate, RowCallbackHandler, RowMapper

Method Summary

Modifier and Type	Method and Description
T	extractData(com.datastax.oss.driver.api.core.cql.ResultSet resultSet) Implementations must implement this method to process the entire ResultSet.

Method Detail

extractData

@Nullable
T extractData(com.datastax.oss.driver.api.core.cql.ResultSet resultSet)
                 throws com.datastax.oss.driver.api.core.DriverException,
                        DataAccessException

Implementations must implement this method to process the entire ResultSet.

Parameters:

resultSet - ResultSet to extract data from.

Returns:

an arbitrary result object, or null if none (the extractor will typically be stateful in the latter case).

Throws:

com.datastax.oss.driver.api.core.DriverException - if a DriverException is encountered getting column values or navigating (that is, there's no need to catch DriverException)

DataAccessException - in case of custom exceptions