如果 xml 节点不在列表中，则追加该节点

Question

我有代码块：

object XmlExample {

  def main(args: Array[String]): Unit = {
    val someXml = 
     <books>
      <book title="The Woman in White">
        <author>Wilkie Collins</author>
      </book> <book title="Great Expectations">
        <author>Charles Dickens</author>
      </book>
    </books>
    println("The xml object is of type: " + someXml.child)


  }

}

我想检查节点 <c1> 是否作为其子节点存在，然后我将其添加为 <c1>Null</c1>

Answer 1

我不确定是否完全理解不存在 因为它的child 。 .. 或你所说 的确切含义我添加了它 但这是我对 添加可选的直接 child 书籍的直接回答 ：

def addC1IfNotHere(someXml: scala.xml.Elem) = (someXml \ "c1") match {
  case Seq() =>
    someXml.copy(child = <c1>Null</c1> +: someXml.child)
  case _ => someXml
}

这就像：

val someXmlWithC1 = 
<books>
   <c1>anything else</c1>
   <book title="The Woman in White">
    <author>Wilkie Collins</author>
   </book> <book title="Great Expectations">
    <author>Charles Dickens</author>
  </book>
</books>
val someXmlWithoutC1 = 
<books>
   <book title="The Woman in White">
    <author>Wilkie Collins</author>
   </book> <book title="Great Expectations">
    <author>Charles Dickens</author>
  </book>
</books>
val hasItsOriginalC1 = addC1IfNotHere(someXmlWithC1)
val hasANewC1 = addC1IfNotHere(someXmlWithoutC1)
println(hasItsOriginalC1)
println(hasANewC1)

应该正常打印：

<books>
   <c1>anything else</c1>
   <book title="The Woman in White">
    <author>Wilkie Collins</author>
   </book> <book title="Great Expectations">
    <author>Charles Dickens</author>
  </book>
</books>
<books><c1>Null</c1>
   <book title="The Woman in White">
    <author>Wilkie Collins</author>
   </book> <book title="Great Expectations">
    <author>Charles Dickens</author>
  </book>
</books>

希望对您有所帮助。当 c1 不在您预期的位置或其他地方时，请不要犹豫。

如果 xml 节点不在列表中，则追加该节点

append xml node if it not present in the list

scala

scala-xml