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Some stellar general purpose utils.
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/*
* Copyright (C) Posten Norge AS
*
* 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
*
* http://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 no.digipost.jdbc;
import no.digipost.function.ThrowingBiFunction;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Optional;
import java.util.function.Function;
/**
* A {@code ColumnMapper} which is apropriate for retrieving {@code nullable} columns
* from a {@link ResultSet}. If the result from a mapping (or any {@link Function} in the mapping chain)
* is {@code null}, the result is always {@link Optional#empty()}, and the chain of any remaining
* mapping functions are "short-circuited" and not invoked.
*
* @param The type of the {@link Optional} result.
*/
@FunctionalInterface
public interface NullableColumnMapper extends ColumnMapper> {
static NullableColumnMapper of(ThrowingBiFunction function) {
return (name, rs) -> function.andThen(Optional::ofNullable).apply(name, rs);
}
/**
* Create a new {@code NullableColumnMapper} which will map the result of this one
* using the given {@link Function function}.
*
* @param The type of {@code Optional} the new mapper yields from a {@code ResultSet}
* @param mapper the mapping function. This will not be called if the result of the mapping chain is already
* {@link Optional#empty()}.
* @return the new mapper
*/
default NullableColumnMapper andThen(Function mapper) {
return (name, rs) -> this.map(name, rs).map(mapper);
}
}