Convert JSON to Groovy Class

json2gclass.groovy

import groovy.json.JsonSlurper
import groovy.transform.Field

def json = new JsonSlurper().parse(System.in)

if (!(json instanceof Map)) {
  System.err.println "Input was not json"
  System.exit 1
}

if (args.length != 1) {
  System.err.println "Expected arg: className"
  System.exit 2
}

@Field boolean hasLinks = false

String buildClass(String name, Map json, int offset = 0) {
  def indent = "  " * offset
  def s = new StringWriter()
  def additionalClasses = []
  s.println "${indent}@ToString(includePackage = false, includeNames = true)"
  s.println "${indent}class ${name} {"

  json.each { String k, v ->
    if (v instanceof String) {
      s.println "${indent}  String $k"
    } else if (v instanceof Boolean) {
      s.println "${indent}  Boolean $k"
    } else if (v instanceof Number) {
      s.println "${indent}  BigDecimal $k"
    } else if (v instanceof Map) {
      if (v.size() == 1 && v.keySet().toList()[0] == 'href') {
        s.println "${indent}  Link $k"
        hasLinks = true
      } else {
        additionalClasses << buildClass(toClassName(k), v, offset + 1)
        s.println "${indent}  ${toClassName(k)} $k"
      }
    } else if (v instanceof List) {
      if (v.size()) {
        if (v[0] instanceof String) {
          s.println "${indent}  List<String> $k"
        } else if (v[0] instanceof Boolean) {
          s.println "${indent}  List<Boolean> $k"
        } else if (v[0] instanceof Number) {
          s.println "${indent}  List<BigDecimal> $k"
        } else if (v[0] instanceof Map) {
          additionalClasses << buildClass(toClassName(k), v[0], offset + 1)
          s.println "${indent}  List<${toClassName(k)}> $k"
        } else {
          s.println "${indent}  // List<!!> $k"
        }
      }
    } else {
      s.println "${indent}  //Object $k"
    }
  }
  if (additionalClasses)
    s.println('')
  s.println additionalClasses.join('\n')
  s.println "${indent}}"
  if (additionalClasses)
    s.println('')
  s.toString()
}

private String toClassName(String k) {
  k.startsWith('_') ?
      toClassName(k[1..-1]) :
      "${k[0].toUpperCase()}${k[1..-1]}Type"
}

println buildClass(args[0], json)
if (hasLinks) {
  println """\
    |@ToString(includePackage = false, includeNames = true)
    |class Link {
    |  String href
    |}
  """.stripMargin()
}