akka.stream.alpakka.csv.scaladsl.CsvToMap.scala Maven / Gradle / Ivy

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Alpakka is a Reactive Enterprise Integration library for Java and Scala, based on Reactive Streams and Akka.
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/*
 * Copyright (C) since 2016 Lightbend Inc. 
 */

package akka.stream.alpakka.csv.scaladsl

import java.nio.charset.{Charset, StandardCharsets}

import akka.NotUsed
import akka.stream.alpakka.csv.impl.{CsvToMapAsStringsStage, CsvToMapStage}
import akka.stream.scaladsl.Flow
import akka.util.ByteString

object CsvToMap {

  /**
   * A flow translating incoming [[scala.List]] of [[akka.util.ByteString]] to a map of String and ByteString using the stream's first
   * element's values as keys.
   * @param charset the charset to decode [[akka.util.ByteString]] to [[scala.Predef.String]], defaults to UTF-8
   */
  def toMap(charset: Charset = StandardCharsets.UTF_8): Flow[List[ByteString], Map[String, ByteString], NotUsed] =
    Flow.fromGraph(
      new CsvToMapStage(columnNames = None,
                        charset,
                        combineAll = false,
                        customFieldValuePlaceholder = Option.empty,
                        headerPlaceholder = Option.empty)
    )

  /**
   * A flow translating incoming [[scala.List]] of [[akka.util.ByteString]] to a map of String keys and values using the stream's first
   * element's values as keys.
   * @param charset the charset to decode [[akka.util.ByteString]] to [[scala.Predef.String]], defaults to UTF-8
   */
  def toMapAsStrings(charset: Charset = StandardCharsets.UTF_8): Flow[List[ByteString], Map[String, String], NotUsed] =
    Flow.fromGraph(
      new CsvToMapAsStringsStage(columnNames = None,
                                 charset,
                                 combineAll = false,
                                 customFieldValuePlaceholder = Option.empty,
                                 headerPlaceholder = Option.empty)
    )

  /**
   * A flow translating incoming [[scala.List]] of [[akka.util.ByteString]] to a map of String and ByteString
   * using the stream's first element's values as keys. If the header values are shorter than the data (or vice-versa)
   * placeholder elements are used to extend the shorter collection to the length of the longer.
   * @param charset the charset to decode [[akka.util.ByteString]] to [[scala.Predef.String]], defaults to UTF-8
   * @param customFieldValuePlaceholder placeholder used when there is more data than headers.
   * @param headerPlaceholder placeholder used when there are more headers than data.
   */
  def toMapCombineAll(
      charset: Charset = StandardCharsets.UTF_8,
      customFieldValuePlaceholder: Option[ByteString] = None,
      headerPlaceholder: Option[String] = None
  ): Flow[List[ByteString], Map[String, ByteString], NotUsed] =
    Flow.fromGraph(
      new CsvToMapStage(columnNames = None,
                        charset,
                        combineAll = true,
                        customFieldValuePlaceholder = customFieldValuePlaceholder,
                        headerPlaceholder = headerPlaceholder)
    )

  /**
   * A flow translating incoming [[scala.List]] of [[akka.util.ByteString]] to a map of String keys and values
   * using the stream's first element's values as keys. If the header values are shorter than the data (or vice-versa)
   * placeholder elements are used to extend the shorter collection to the length of the longer.
   * @param charset the charset to decode [[akka.util.ByteString]] to [[scala.Predef.String]], defaults to UTF-8
   * @param customFieldValuePlaceholder placeholder used when there is more data than headers.
   * @param headerPlaceholder placeholder used when there are more headers than data.
   */
  def toMapAsStringsCombineAll(
      charset: Charset = StandardCharsets.UTF_8,
      customFieldValuePlaceholder: Option[String] = None,
      headerPlaceholder: Option[String] = None
  ): Flow[List[ByteString], Map[String, String], NotUsed] =
    Flow.fromGraph(
      new CsvToMapAsStringsStage(columnNames = None,
                                 charset,
                                 combineAll = true,
                                 customFieldValuePlaceholder = customFieldValuePlaceholder,
                                 headerPlaceholder = headerPlaceholder)
    )

  /**
   * A flow translating incoming [[scala.List]] of [[akka.util.ByteString]] to a map of String and ByteString using the given headers
   * as keys.
   * @param headers column names to be used as map keys
   */
  def withHeaders(headers: String*): Flow[List[ByteString], Map[String, ByteString], NotUsed] =
    Flow.fromGraph(
      new CsvToMapStage(Some(headers.toList),
                        StandardCharsets.UTF_8,
                        combineAll = false,
                        customFieldValuePlaceholder = Option.empty,
                        headerPlaceholder = Option.empty)
    )

  /**
   * A flow translating incoming [[scala.List]] of [[akka.util.ByteString]] to a map of String keys and values using the given headers
   * as keys.
   * @param charset the charset to decode [[akka.util.ByteString]] to [[scala.Predef.String]]
   * @param headers column names to be used as map keys
   */
  def withHeadersAsStrings(
      charset: Charset,
      headers: String*
  ): Flow[List[ByteString], Map[String, String], NotUsed] =
    Flow.fromGraph(
      new CsvToMapAsStringsStage(Some(headers.toList),
                                 charset,
                                 combineAll = false,
                                 customFieldValuePlaceholder = Option.empty,
                                 headerPlaceholder = Option.empty)
    )
}