org.springframework.data.cassandra.core.cql

Interface AsyncResultSetExtractor<T>

All Known Implementing Classes:

AsyncCqlTemplate.AsyncRowCallbackHandlerResultSetExtractor, AsyncRowMapperResultSetExtractor

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 AsyncResultSetExtractor<T>

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

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

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

Since:

3.0

Author:

Mark Paluch

See Also:

AsyncCqlTemplate, RowMapper

Method Summary

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

Method Detail

extractData

@Nullable
ListenableFuture<T> extractData(com.datastax.oss.driver.api.core.cql.AsyncResultSet resultSet)
                                   throws com.datastax.oss.driver.api.core.DriverException,
                                          DataAccessException

Implementations must implement this method to process the entire AsyncResultSet.

Parameters:

resultSet - AsyncResultSet 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