co.cask.wrangler.steps.column.CleanseColumnNames Maven / Gradle / Ivy

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/*
 * Copyright © 2017 Cask Data, Inc.
 *
 * 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 co.cask.wrangler.steps.column;

import co.cask.wrangler.api.AbstractStep;
import co.cask.wrangler.api.PipelineContext;
import co.cask.wrangler.api.Record;
import co.cask.wrangler.api.StepException;
import co.cask.wrangler.api.Usage;

import java.util.List;

/**
 * Cleanses columns names.
 *
 * 
 *   

 *     Lowercases the column name
 *     Trims space
 *     Replace characters other than [A-Z][a-z][_] with empty string.
 *   
 * 
 */
@Usage(
  directive = "cleanse-column-names",
  usage = "cleanse-column-names",
  description = "Sanatizes column names: trims, lowercases, and replaces all but [A-Z][a-z][0-9]_ " +
                  "with an underscore '_'."
)
public class CleanseColumnNames extends AbstractStep {
  public CleanseColumnNames(int lineno, String directive) {
    super(lineno, directive);
  }

  /**
   * Executes a wrangle step on single {@link Record} and return an array of wrangled {@link Record}.
   *
   * @param records List of input {@link Record} to be wrangled by this step.
   * @param context {@link PipelineContext} passed to each step.
   * @return Wrangled List of {@link Record}.
   */
  @Override
  public List execute(List records, PipelineContext context) throws StepException {
    for (Record record : records) {
      for (int i = 0; i < record.length(); ++i) {
        String column = record.getColumn(i);
        // Trims
        column = column.trim();
        // Lower case columns
        column = column.toLowerCase();
        // Filtering unwanted characters
        column = column.replaceAll("[^a-zA-Z0-9_]", "_");
        record.setColumn(i, column);
      }
    }
    return records;
  }
}