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/*
* Copyright 2016-2020 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 org.reactivestreams.Publisher;
import org.springframework.dao.DataAccessException;
import org.springframework.data.cassandra.ReactiveResultSet;
import com.datastax.driver.core.exceptions.DriverException;
/**
* Callback interface used by {@link ReactiveCqlTemplate}'s query methods. Implementations of this interface perform the
* actual work of extracting results from a {@link ReactiveResultSet}, but don't need to worry about exception handling.
* {@link DriverException}s will be caught and handled by the calling {@link ReactiveCqlTemplate}.
*
* This interface is mainly used within the CQL framework itself. A {@link RowMapper} is usually a simpler choice for
* {@link ReactiveResultSet} processing, mapping one result object per row instead of one result object for the entire
* {@link ReactiveResultSet}.
*
* Note: {@link ReactiveResultSetExtractor} object is typically stateless and thus reusable, as long as it doesn't
* access stateful resources or keep result state within the object.
*
* @author Mark Paluch
* @since 2.0
* @see ReactiveCqlTemplate
* @see RowCallbackHandler
* @see RowMapper
*/
@FunctionalInterface
public interface ReactiveResultSetExtractor {
/**
* Implementations must implement this method to process the entire {@link ReactiveResultSet}.
*
* @param resultSet {@link ReactiveResultSet} to extract data from, must not be {@literal null}.
* @return an arbitrary result object {@link Publisher}.
* @throws DriverException if a {@link DriverException} is encountered getting column values or navigating (that is,
* there's no need to catch {@link DriverException}).
* @throws DataAccessException in case of custom exceptions.
*/
Publisher extractData(ReactiveResultSet resultSet) throws DriverException, DataAccessException;
}