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Data Repository Support for Micronaut

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/*
 * Copyright 2017-2023 original 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 io.micronaut.data.runtime.mapper;

import io.micronaut.core.annotation.NonNull;
import io.micronaut.core.type.Argument;
import io.micronaut.core.util.StringUtils;
import io.micronaut.data.exceptions.DataAccessException;
import io.micronaut.data.model.JsonDataType;
import io.micronaut.json.JsonMapper;

import java.io.IOException;

/**
 * The wrapper around {@link JsonMapper} to read JSON values from the result set.
 *
 * @author radovanradic
 * @since 4.0.0
 *
 * @param  the result set type
 */
public interface JsonColumnReader {

    /**
     * JSON string null value.
     */
    String NULL_VALUE = "null";

    /**
     * Reads JSON column from the result set and returns as expected type.
     *
     * @param resultReader the result reader
     * @param resultSet the result set
     * @param columnName the column name
     * @param jsonDataType the JSON type
     * @param argument the result type argument
     * @return object of type T read from JSON column
     * @param  the result type
     */
    default   T readJsonColumn(ResultReader resultReader, S resultSet, String columnName, JsonDataType jsonDataType, Argument argument) {
        String data = resultReader.readString(resultSet, columnName);
        if (StringUtils.isEmpty(data) || data.equals(NULL_VALUE)) {
            return null;
        }
        if (argument.getType().equals(String.class)) {
            return (T) data;
        }
        try {
            return getJsonMapper().readValue(data, argument);
        } catch (IOException e) {
            throw new DataAccessException("Failed to read from JSON field [" + columnName + "].", e);
        }
    }

    /**
     * @return the json mapper
     */
    @NonNull JsonMapper getJsonMapper();
}