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Helidon Reactive Database Client API
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/*
 * Copyright (c) 2019, 2023 Oracle and/or its affiliates.
 *
 * 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 io.helidon.dbclient;

import java.util.List;
import java.util.Map;

import io.helidon.dbclient.spi.DbClientBuilder;
import io.helidon.dbclient.spi.DbClientProvider;

/**
 * A mapper to map database objects to/from a specific type.
 * 
 * Mappers can be either provided through {@link DbClientProvider} or registered directly
 * with the {@link DbClientBuilder#addMapper(DbMapper, Class)}.
 *
 * @param  target mapping type
 */
public interface DbMapper {

    /**
     * Read database row and convert it to target type instance.
     *
     * @param row source database row
     * @return target type instance containing database row
     */
    T read(DbRow row);

    /**
     * Convert target type instance to a statement named parameters map.
     *
     * @param value mapping type instance containing values to be set into statement
     * @return map of statement named parameters mapped to values to be set
     * @see DbStatement#namedParam(Object)
     */
    Map toNamedParameters(T value);

    /**
     * Convert target type instance to a statement indexed parameters list.
     * 
     * Using indexed parameters with typed values is probably not going to work nicely, unless
     * the order is specified and the number of parameters is always related the provided value.
     * There are cases where this is useful though - e.g. for types that represent an iterable collection.
     *
     * @param value mapping type instance containing values to be set into statement
     * @return map of statement named parameters mapped to values to be set
     * @see DbStatement#indexedParam(Object)
     */
    List toIndexedParameters(T value);

}