scala-csvreader

Scala CSV file (stream) reader

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CsvReader

CsvReader is simple CSV reader with pure Scala.

The reader supports:

• arbitrary case class for record data

• file with or without header line

• setting either continue or stop after error during parsing a record

• setting different delimiter character

• error handling

• record handling

Usage

Record Data Class

Record data class is a case class. For example:

case class TestData1(i: Int, s: String, d: Double)

Some parameters may be Option, For example

case class TestData2(i: Int, s: Option[String], d: Double) {
  def this(params: Seq[String]) {
    this(params(0).toInt,
      if (params(1).isEmpty)
        None
      else
        Some(params(1)),
      params(2).toDouble
    )
  }
}

Note in this case the auxiliary constructor should be defined!

How to work with CsvReader

    def recordHandler(record:TestData]:Unit={
    ...
    }

    def errorHandler(error:String]:Unit={
    ...
    }

    CsvReader.reader[TestData](Source.fromFile("data.csv"), recordHandler, errorHandler)
      .parse()

or

    // Empty record handler
    def handler(testData: TestData1): Unit = {}

    val list = CsvReader.reader[TestData1](Source.fromResource("test-data1.csv"), handler, errorHandler).toList

Use of modificators:

• withDelimiter

• withContinueOnError

• withHeaderLine

• withCustomTransformer

How to work with custom transformer

Custom transformer allows to customize creating an object.

recordHandler method should be called for each created object.

errorHandler method should be called for each error during creating object.

Example:

    def transformer(line: Seq[String], recordHandler: TestData1 => Unit, errorHandler: String => Unit): TestData1 = {
        try {
          val data = TestData1(333, "test", 77.12)
          recordHandler(data)
          data
        } catch {
          case e: Exception =>
            errorHandler(e.getMessage)
            throw e
       }
    }

See CsvReaderTest test("customTransformer") and test("customTransformer with error")

CsvStreamReader

CsvStreamReader is CSV reader with using the Akka stream.

The reader supports:

• arbitrary case class for record data

• file with or without header line

• setting either continue or stop after error during parsing a record

• setting different delimiter character

• error handling

• record handling

Usage

Record Data Class

Record data class is a case class. For example:

case class TestData1(i: Int, s: String, d: Double)

Some parameters may be Option, For example

case class TestData2(i: Int, s: Option[String], d: Double) {
  def this(params: Seq[String]) {
    this(params(0).toInt,
      if (params(1).isEmpty)
        None
      else
        Some(params(1)),
      params(2).toDouble
    )
  }
}

Note in this case the auxiliary constructor should be defined!

How to work with CsvStreamReader

 def recordHandler(record:TestData]:Unit={
  ...
 }

 def errorHandler(error:String]:Unit={
 ...
 }

 implicit val actorSystem: ActorSystem = ActorSystem("CsvStreamReaderTest")
 implicit val materializer: ActorMaterializer = ActorMaterializer()

 val reader = CsvStreamReader.reader(Source.fromResource("test-data1.csv"), recordHandler, errorHandler)

 Await.ready(reader.run(), Duration.Inf)
 source.close()
 actorSystem.terminate()

How to get list of items

 def errorHandler(error:String]:Unit={
 ...
 }

 implicit val actorSystem: ActorSystem = ActorSystem("CsvStreamReaderTest")
 implicit val materializer: ActorMaterializer = ActorMaterializer()
 val list = ListBuffer.empty[TestData1]

 val reader = CsvStreamReader.reader(Source.fromResource("test-data1.csv"),
    item => list += item,
    errorHandler)

 Await.ready(reader.run(), Duration.Inf)
 println(s"list.length=${list.length}")
 source.close()
 actorSystem.terminate()

Use of modificators:

• withDelimiter

• withContinueOnError

• withHeaderLine

• withCustomTransformer

How to work with custom transformer

See "How to work with custom transformer" for CsvReader (above)