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/*
* Copyright 2013-2020 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.data.cassandra.core.cql;
import com.datastax.driver.core.Row;
import com.datastax.driver.core.exceptions.DriverException;
/**
* An interface used by {@link CqlTemplate} for processing rows of a {@link com.datastax.driver.core.ResultSet} on a
* per-row basis. Implementations of this interface perform the actual work of processing each row but don't need to
* worry about exception handling. {@link DriverException}s will be caught and handled by the calling
* {@link CqlTemplate}.
*
* In contrast to a {@link ResultSetExtractor}, a {@link RowCallbackHandler} object is typically stateful: It keeps the
* result state within the object, to be available for later inspection.
*
* Consider using a {@link RowMapper} instead if you need to map exactly one result object per row, assembling them into
* a List.
*
* @author Mark Paluch
* @see CqlTemplate
* @see RowMapper
* @see ResultSetExtractor
*/
@FunctionalInterface
public interface RowCallbackHandler {
/**
* Implementations must implement this method to process each row of data in the
* {@link com.datastax.driver.core.ResultSet}. This method is only supposed to extract values of the current row.
*
* Exactly what the implementation chooses to do is up to it: A trivial implementation might simply count rows, while
* another implementation might build an XML document.
*
* @param row the {@link Row} to process (pre-initialized for the current row).
* @throws DriverException if a {@link DriverException} is encountered getting column values (that is, there's no need
* to catch {@link DriverException}).
*/
void processRow(Row row) throws DriverException;
}