Select a range of nodes in an XML file using an XPath query

In the following example we can see how to use the position() selector in a XPath query to select a nodes range.

Consider the following XML:

<?xml version="1.0" encoding="utf-8" ?>
<Data>
  <Books>
    <book>
      <name>Book 1</name>
      <price>10</price>
    </book>
    <book>
      <name>Book 2</name>
      <price>81</price>
    </book>
    <book>
      <name>Book 3</name>
      <price>58</price>
    </book>
    <book>
      <name>Book 4</name>
      <price>43</price>
    </book>
    <book>
      <name>Book 5</name>
      <price>54</price>
    </book>
    <book>
      <name>Book 6</name>
      <price>22</price>
    </book>
  </Books>
</Data>

Suppose to select the nodes “book” in the range 2-4. The XPath query is the following:

//book[position() >= 2  and position() <= 4]

Nell’esempio seguente vediamo come utilizzare il selettore position() in una query XPath per selezionare un intervallo di nodi.

Consideriamo il seguente XML:

<?xml version="1.0" encoding="utf-8" ?>
<Data>
  <Books>
    <book>
      <name>Book 1</name>
      <price>10</price>
    </book>
    <book>
      <name>Book 2</name>
      <price>81</price>
    </book>
    <book>
      <name>Book 3</name>
      <price>58</price>
    </book>
    <book>
      <name>Book 4</name>
      <price>43</price>
    </book>
    <book>
      <name>Book 5</name>
      <price>54</price>
    </book>
    <book>
      <name>Book 6</name>
      <price>22</price>
    </book>
  </Books>
</Data>

Supponiamo di voler selezionare i nodi “book” nell’intervallo 2-4, cioè selezionare i nodi relativi ai libri 2,3 e 4. La query XPath da utilizzare è la seguente:

//book[position() >= 2  and position() <= 4]