Given this XML, the following expression returns all <stock> elements:
scala> x \ "stock"
res0: scala.xml.NodeSeq =
NodeSeq(<stock>AAPL</stock>, <stock>AMZN</stock>, <stock>GOOG</stock>)
As shown in the REPL output, this returns an instance of a NodeSeq, which is a simple
wrapper around Seq[Node] (a sequence of nodes). Like the Elem class, NodeSeq supports
the \ and \\ search methods, as well as the usual large variety of collection methods.
Once you have a NodeSeq, you can work with the data it contains. For instance, you can
create a list of stock symbols like this:
scala> (x \ "stock").map(_.text)
res1: scala.collection.immutable.Seq[String] = List(AAPL, AMZN, GOOG)
If this is confusing, it can help to see it broken down into smaller steps. First, get a
sequence of elements with the \ method, and assign the result to a variable:
scala> val nodes = x \ "stock"
nodes: scala.xml.NodeSeq =
NodeSeq(<stock>AAPL</stock>, <stock>AMZN</stock>, <stock>GOOG</stock>)
You can see that nodes is a variable of type NodeSeq. Each individual node is of type
Elem:
scala> for (n <- nodes) println(n.getClass)
class scala.xml.Elem
class scala.xml.Elem
class scala.xml.Elem
Each element contains its XML tag as well as its data:
scala> for (n <- nodes) println(n)
<stock>AAPL</stock>
<stock>AMZN</stock>
<stock>GOOG</stock>
So, to extract only the data from each node, call the text method:
scala> for (n <- nodes) println(n.text)
AAPL
AMZN
GOOG
Putting this together, you can create a list of stock names using a for/yield loop:
scala> val stockNames = for (n <- nodes) yield n.text
stockNames: scala.collection.immutable.Seq[String] = List(AAPL, AMZN, GOOG)
That loop is equivalent to this map method call:
scala> val stockNames = nodes.map(_.text)
stockNames: scala.collection.immutable.Seq[String] = List(AAPL, AMZN, GOOG)
16 | Bonus Chapter: XML and XPath
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