XPath - Examples

// equals descendant-or-self::node()/

Watch it! // is expensive since it is relative path and has to traverse all tree!

Case sensitive names of nodes, elements and attributes !

//Person   is not equal   //person

Everything inside [ ] is expression. When you need another expression inside [ ] sometimes you can write:

//person[address/city]
; in this case / is used inside [] instead of :
//person[address[city]]

Relative and absolute path

Example of relative path:

//person[1]  

; this will return EVERY person that is the FIRST child of its parent ! In sample this will include "Oliver child person" and John Sullivan.

Another relative:

//*/*/*/*/name()

; every element that has 4 ancestors ( city -> address -> person -> persons -> root

String='city'
String='person'
String='city'

Absolute path:

/persons/person[1]

; or use :

(//person)[1]

; this will return only FIRST child of persons node!

Sample XML:

<?xml-stylesheet type="text/xml" href="persons.xsl"?>
<persons>
  <person>
    <id>1</id>
    <age>20</age>
    <first-name>
      John
    </first-name>
    <last-name>
      Sullivan
    </last-name>
    <salary>200.00</salary>
  </person>
  <person>
    <id>2</id>
    <age>25</age>
    <first-name>
      Mark
    </first-name>
    <last-name>
      Johny
    </last-name>
  </person>
  <person>
    <address>
      <city state="France">Paris</city>
    </address>
    <id>3</id>
    <age>30</age>
    <first-name>
      Mark
    </first-name>
    <last-name>
      Johny
    </last-name>
  </person>
  <person>
    <address>
      <person>
        Oliver child person
      </person>
      <city state="UK">London</city>
    </address>
    <id>4</id>
    <age>40</age>
    <first-name>
      Oliver
    </first-name>
    <last-name>
      Johny
    </last-name>
    <salary>300.00</salary>
  </person>
  <person>
    <id>5</id>
    <age>60</age>
    <first-name>
      Kris
    </first-name>
    <last-name>
      Sullivan
    </last-name>
    <salary>300.00</salary>
  </person>
</persons>

1. Get all persons:

//person

2. Get all persons text:

//person/string()

3. Get second person:

//person[2]

;returns: Mark, Johny, Id=2

4. Get fourth person:

//person[position() eq 4]

;returns: Oliver, Johny, Id=4

5. Get first two persons:

//person[position() lt 3]

6. Get persons that have element Salary:

//person[salary]

7. Get every person whose next person sibling in document order has salary that equals to preceding person.

//person[sallary = following-sibling::person/sallary]

8. Get persons whose age is between 20 and 60 and has position before filtering greater than 3 :

//person[age gt "20" and age lt "60" and position() gt 3]

9. Find persons whose salary is greater than salary of first person that has info about salary:

//person[salary gt //person[salary][1]/salary/text() ]

10. Look for persons that have City info. For them look their parent Person and person Id.

//person/address/city/../../id

11. Find cities whose attribute State is France:

//person/address/city[@state="France"]

Example of sequences introduced in XPath 2.0:

12. Iterate through all persons and output first-name value:

for $n in /persons/person return $n/first-name

13. Iterate all persons with value for salary. On each iteration calculate second sequence by multiplying current person id element value from from first sequence with 2.

for $n in /persons/person[salary], $id in $n/id * 2 return $id

14. Are there any person that has salary greater than $299.00 :

every $p in /persons/person/salary satisfies $p gt "299.00"

;returns true

15. Do all persons older than 18 have salary element ?

every $adult in /persons/person[age gt "30"] satisfies $adult[salary]

;returns true

16. Do at least one person that have city info have salary info:

some $personwcity in /persons/person/address/city satisfies $personwcity/../..[salary]

;returns true

17. Show last Person from Persons node:

/persons/person[last()]

18. Show first-name of persons whose Id is greater than 3. Observe use of dot  as self reference.

/persons/person/id[. gt "3"]/../first-name

19. Show first and last person.

(//person)[1] union (//person)[last()]

20. Show only persons with city info and salary info

Version 1:
//person[address/city] intersect //person[salary]

Version 2:
//person[address/city and salary]

21. Show persons that DON'T have salary:

//person except //person[salary]

22. Show all persons ONLY if there are 2 or more persons with address info:

//person[count(/persons/person/address) ge 2]