com.flipkart.aesop.mysqldatalayer.delete.MySQLDeleteDataLayer.java Source code

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Here is the source code for com.flipkart.aesop.mysqldatalayer.delete.MySQLDeleteDataLayer.java

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/*******************************************************************************
 *
 * Copyright 2012-2015, 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 obta 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 com.flipkart.aesop.mysqldatalayer.delete;

import com.flipkart.aesop.destinationoperation.DeleteDestinationStoreProcessor;
import com.flipkart.aesop.destinationoperation.JDBCDataLayer;
import com.flipkart.aesop.destinationoperation.utils.DataLayerConstants;
import com.flipkart.aesop.destinationoperation.utils.DataLayerHelper;
import com.flipkart.aesop.event.AbstractEvent;
import com.flipkart.aesop.mysqldatalayer.upsert.MySQLUpsertDataLayer;
import com.linkedin.databus.client.pub.ConsumerCallbackResult;
import com.linkedin.databus.core.DbusOpcode;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;

import java.util.Map;
import java.util.Set;

/**
 * MySQL Delete Data Layer. Persists {@link DbusOpcode#DELETE} events to MySQL.
 * @author Prakhar Jain
 * @see MySQLUpsertDataLayer
 */
public class MySQLDeleteDataLayer extends DeleteDestinationStoreProcessor implements JDBCDataLayer {
    /** JDBC Template Map, with Namespace name as key and the corresponding JDBC template as value. */
    private Map<String, NamedParameterJdbcTemplate> jdbcTemplateMap;

    /**
     * Field Constructor.
     * @param jdbcTemplateMap
     */
    public MySQLDeleteDataLayer(Map<String, NamedParameterJdbcTemplate> jdbcTemplateMap) {
        this.jdbcTemplateMap = jdbcTemplateMap;
    }

    public Map<String, NamedParameterJdbcTemplate> getJdbcTemplateMap() {
        return jdbcTemplateMap;
    }

    @Override
    protected ConsumerCallbackResult delete(AbstractEvent event) {
        String deleteQuery = getDeleteQuery(event);
        NamedParameterJdbcTemplate jdbcTemplate = jdbcTemplateMap.get(event.getNamespaceName());
        Map<String, Object> nullValueColumnMapping = DataLayerHelper
                .generateColumnMappingWithNullValues(event.getFieldMapPair(), event.getPrimaryKeySet());
        jdbcTemplate.update(deleteQuery, nullValueColumnMapping);
        return ConsumerCallbackResult.SUCCESS;
    }

    /**
     * Generates Delete Query using {@link #buildQuery(String, String, StringBuilder, StringBuilder)} and
     * {@link #populateDeleteQueryParts(Map, Set, StringBuilder, StringBuilder)} helper functions.
     * @param event
     * @return Delete Query
     */
    private String getDeleteQuery(AbstractEvent event) {
        StringBuilder updateClauseStringBuilder = new StringBuilder();
        StringBuilder whereClauseStringbuilder = new StringBuilder();

        populateDeleteQueryParts(event.getFieldMapPair(), event.getPrimaryKeySet(), updateClauseStringBuilder,
                whereClauseStringbuilder);

        return buildQuery(event.getNamespaceName(), event.getEntityName(), updateClauseStringBuilder,
                whereClauseStringbuilder);
    }

    /**
     * Helper Function for {@link #getDeleteQuery(AbstractEvent)}.
     * @param fieldMap
     * @param primaryKeySet
     * @param updateClauseStringBuilder
     * @param whereClauseStringbuilder
     */
    private void populateDeleteQueryParts(Map<String, Object> fieldMap, Set<String> primaryKeySet,
            StringBuilder updateClauseStringBuilder, StringBuilder whereClauseStringbuilder) {
        for (String columnName : fieldMap.keySet()) {
            if (!primaryKeySet.contains(columnName)) {
                updateClauseStringBuilder.append(
                        columnName + DataLayerConstants.EQUALTO_AND_COLON + columnName + DataLayerConstants.COMMA);
            } else {
                whereClauseStringbuilder.append(
                        columnName + DataLayerConstants.EQUALTO_AND_COLON + columnName + DataLayerConstants.AND);
            }
        }
    }

    /**
     * Helper Function for {@link #getDeleteQuery(AbstractEvent)}.
     * @param namespace
     * @param entity
     * @param updateClauseStringBuilder
     * @param whereClauseStringbuilder
     * @return Delete Query
     */
    private String buildQuery(String namespace, String entity, StringBuilder updateClauseStringBuilder,
            StringBuilder whereClauseStringbuilder) {
        StringBuilder deleteQuery = new StringBuilder();

        deleteQuery.append("UPDATE ");
        deleteQuery.append(namespace + "." + entity);
        deleteQuery.append(" SET ");
        deleteQuery.append(updateClauseStringBuilder.substring(0, updateClauseStringBuilder.length() - 1));
        deleteQuery.append(" WHERE ");
        deleteQuery.append(whereClauseStringbuilder.substring(0, whereClauseStringbuilder.length() - 5));

        return deleteQuery.toString();
    }
}