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

Go to download

Show more of this group Show more artifacts with this name
Show all versions of akka-stream-alpakka-csv_3 Show documentation

Alpakka is a Reactive Enterprise Integration library for Java and Scala, based on Reactive Streams and Akka.

There is a newer version: 6.0.2

Show newest version

/*
 * 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.CsvFormatter
import akka.stream.scaladsl.{Flow, Source}
import akka.util.ByteString

import scala.collection.immutable

/** Provides CSV formatting flows that convert a sequence of String into their CSV representation
 * in [[akka.util.ByteString]].
 */
object CsvFormatting {

  val Backslash: Char = '\\'
  val Comma: Char = ','
  val SemiColon: Char = ';'
  val Colon: Char = ':'
  val Tab: Char = '\t'
  val DoubleQuote: Char = '"'

  /**
   * Create a Flow for converting iterables to ByteString.
   * @param endOfLine Line ending (default CR, LF)
   * @param quotingStyle Quote all fields, or only fields requiring quotes (default)
   * @param charset Character set, defaults to UTF-8
   * @param byteOrderMark Certain CSV readers (namely Microsoft Excel) require a Byte Order mark, defaults to None
   */
  def format[T <: immutable.Iterable[String]](
      delimiter: Char = Comma,
      quoteChar: Char = DoubleQuote,
      escapeChar: Char = Backslash,
      endOfLine: String = "\r\n",
      quotingStyle: CsvQuotingStyle = CsvQuotingStyle.Required,
      charset: Charset = StandardCharsets.UTF_8,
      byteOrderMark: Option[ByteString] = None
  ): Flow[T, ByteString, NotUsed] = {
    val formatter =
      new CsvFormatter(delimiter, quoteChar, escapeChar, endOfLine, quotingStyle, charset)
    byteOrderMark.fold {
      Flow[T].map(formatter.toCsv).named("CsvFormatting")
    } { bom =>
      Flow[T].map(formatter.toCsv).named("CsvFormatting").prepend(Source.single(bom))
    }

  }
}