org.springframework.data.cassandra.core.cql.RowMapperResultSetExtractor Maven / Gradle / Ivy
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/*
* Copyright 2016-2021 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 java.util.ArrayList;
import java.util.List;
import com.datastax.oss.driver.api.core.DriverException;
import com.datastax.oss.driver.api.core.cql.ResultSet;
import com.datastax.oss.driver.api.core.cql.Row;
import org.springframework.dao.DataAccessException;
import org.springframework.util.Assert;
/**
* Adapter implementation of the {@link ResultSetExtractor} interface that delegates to a {@link RowMapper} which is
* supposed to create an object for each row. Each object is added to the results List of this
* {@link ResultSetExtractor}.
*
* Useful for the typical case of one object per row in the database table. The number of entries in the results will
* match the number of rows.
*
* Note that a {@link RowMapper} object is typically stateless and thus reusable.
*
* @author Mark Paluch
* @since 2.0
* @see RowMapper
* @see CqlTemplate
*/
public class RowMapperResultSetExtractor implements ResultSetExtractor> {
private final int rowsExpected;
private final RowMapper rowMapper;
/**
* Create a new {@link RowMapperResultSetExtractor}.
*
* @param rowMapper the {@link RowMapper} which creates an object for each row, must not be {@literal null}.
*/
public RowMapperResultSetExtractor(RowMapper rowMapper) {
this(rowMapper, 0);
}
/**
* Create a new {@link RowMapperResultSetExtractor}.
*
* @param rowMapper the {@link RowMapper} which creates an object for each row, must not be {@literal null}.
* @param rowsExpected the number of expected rows (just used for optimized collection handling).
*/
public RowMapperResultSetExtractor(RowMapper rowMapper, int rowsExpected) {
Assert.notNull(rowMapper, "RowMapper is must not be null");
this.rowMapper = rowMapper;
this.rowsExpected = rowsExpected;
}
/* (non-Javadoc)
* @see org.springframework.data.cassandra.core.cql.ResultSetExtractor#extractData(com.datastax.driver.core.ResultSet)
*/
@Override
public List extractData(ResultSet resultSet) throws DriverException, DataAccessException {
List results = (this.rowsExpected > 0 ? new ArrayList<>(this.rowsExpected) : new ArrayList<>());
int rowNumber = 0;
for (Row row : resultSet) {
results.add(this.rowMapper.mapRow(row, rowNumber++));
}
return results;
}
}