Java 8 dates and times

Java 8 comes with a better thought out dates and times API. Unfortunately, it cannot be supported as part of the core kantan.xpath API - we still support Java 7. There is, however, a dedicated optional module that you can include by adding the following line to your build.sbt file:

libraryDependencies += "com.nrinaudo" %% "kantan.xpath-java8" % "0.5.3"

You then need to import the corresponding package:

import kantan.xpath.java8._

And this will bring NodeDecoder instances in scope for the following types:

These will use the default Java 8 formats. For example:

import kantan.xpath._
import kantan.xpath.implicits._
import java.time._

val input = "<root><date value='1978-10-12'/><date value='2015-01-09'/></root>"

We can decode the bracketed dates without providing an explicit decoder:

input.evalXPath[List[LocalDate]](xp"//date/@value")
// res0: XPathResult[List[LocalDate]] = Right(
//   value = List(1978-10-12, 2015-01-09)
// )

It’s also possible to provide your own format. For example, for LocalDateTime:

import java.time._
import java.time.format.DateTimeFormatter
import kantan.xpath._
import kantan.xpath.implicits._

import kantan.xpath.java8._

val input = "<root><date value='12-10-1978'/><date value='09-01-2015'/></root>"

implicit val decoder: NodeDecoder[LocalDate] = localDateDecoder(DateTimeFormatter.ofPattern("dd-MM-yyyy"))

And we can now simply write:

input.evalXPath[List[LocalDate]](xp"//date/@value")
// res2: XPathResult[List[LocalDate]] = Right(
//   value = List(1978-10-12, 2015-01-09)
// )

Note that while you can pass a DateTimeFormatter directly, the preferred way of dealing with pattern strings is to use the literal syntax provided by kantan.xpath:

localDateDecoder(fmt"dd-MM-yyyy")

The advantage is that this is checked at compile time - invalid pattern strings will cause a compilation error:

localDateDecoder(fmt"FOOBAR")
// error: Illegal format: 'FOOBAR'
// localDateDecoder(fmt"FOOBAR")
//                  ^^^^^^^^^^^
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