Using xpath expression language in Dovetail
Xpath expression is supported by the following components:
Selecting nodes
General
| Expression | Description |
|---|---|
nodename | Selects all nodes with the name "nodename" |
/ | Selects from the root node |
// | Selects nodes in the document from the current node that match the selection no matter where they are |
. | Selects the current node |
.. | Selects the parent of the current node |
@ | Selects attributes |
Things to keep in mind
- Use
*:to ignore namespaces
Examples
This xml is used in the examples below.
<?xml version="1.0" encoding="utf-8"?>
<orders>
<order>
<header orderid="123">
<ordernr>12345</ordernr>
<datetime>2019-04-27T08:58:40.375Z</datetime>
</header>
<orderlines>
<orderline>
<item>1</item>
<value>50</value>
</orderline>
<orderline>
<item>2</item>
<value>100</value>
</orderline>
<orderline>
<item>3</item>
<value>150</value>
</orderline>
</orderlines>
</order>
</orders>
Function examples
Selects path from the root node
Expression: /orders/order/header
Result:
<header orderid="123">
<ordernr>12345</ordernr>
<datetime>2019-04-27T08:58:40.375Z</datetime>
</header>
Selects nodes in the document from the current node that match the selection no matter where they are
Expression: //ordernr
Result:
<ordernr>12345</ordernr>
Selects the textual value of first ordernr element
Expression: //ordernr/text()
Result:
12345
Selects attribute orderid
Expression: //@orderid
Result:
orderid=123
Matches any attribute node
Expression: //@*
Result:
orderid=123
Selects all header elements which have at least one attribute of any kind
Expression: //header[@*]
Result:
<header orderid="123">
<ordernr>12345</ordernr>
<datetime>2019-04-27T08:58:40.375Z</datetime>
</header>
Computes two node-sets with |
Expression: //ordernr | //orderline/value
Result:
<ordernr>12345</ordernr>
<value>50</value>
<value>100</value>
<value>150</value>
Returns a sequence of items from the position specified by the start argument and position
Expression: subsequence(//orderline/value,1)
Result:
<value>50</value>
<value>100</value>
<value>150</value>
Returns the reversed order of the items specified
Expression: reverse(//orderline/value)
Result:
<value>150</value>
<value>100</value>
<value>50</value>
Returns the positions within the sequence of items that are equal to the search item argument
Expression: index-of(//orderline/value/text(),"100")
Result:
2
Returns the argument that is greater than the others
Expression: max(//orderline/item)
Result:
3
Returns the argument that is less than the others
Expression: min(//orderline/item)
Result:
1
Returns the count of nodes
Expression: count(//orderlines/orderline/item)
Result:
3
Returns the sum of the numeric value of each node in the specified node-set
Expression: sum(//order/orderlines/orderline/value)
Result:
300
Returns the average of the argument values
Expression: avg(//order/orderlines/orderline/value)
Result:
100
Returns the length of the specified string
Expression: string-length(//ordernr[1]/text())
Result:
5
Returns the name of the current node or the first node in orders
Expression: name(//orders/*[1])
Result:
order
Returns a string that is created by replacing the given pattern with the replace argument
Expression: replace(name(//orders/*[1]),"e","a")
Result:
ordar
Returns the current dateTime (with timezone)
Expression: current-dateTime()
Result:
2019-05-03T10:23:18.246Z
Returns an integer that represents the year component in the localized value of the argument
Expression: year-from-dateTime(//datetime/text())
Result:
2019
Returns an integer that represents the month component in the localized value of the argument
Expression: month-from-dateTime(//datetime/text())
Result:
4
Returns an integer that represents the day component in the localized value of the argument
Expression: day-from-dateTime(//datetime/text())
Result:
27
Selects the first orderline element that is the child of the orderlines element
Expression: //orderlines[1]
Result:
<orderline>
<item>1</item>
<value>50</value>
</orderline>
Selects the last ‘orderline’ element that is the child of the ‘orderlines’ element
Expression: //orderlines/orderline[last()]
Result:
<orderline>
<item>3</item>
<value>150</value>
</orderline>
Selects the last but one ‘orderline’ element that is the child of the orderlines element
Expression: //orderlines/orderline[last()-1]
Result:
<orderline>
<item>2</item>
<value>100</value>
</orderline>
Selects the first two orderline elements that are children of the orderlines element
Expression: //orderlines/orderline[position()<3]
Result:
<orderline>
<item>1</item>
<value>50</value>
</orderline>
<orderline>
<item>2</item>
<value>100</value>
</orderline>
Operators
| Operator | Description |
|---|---|
| | Computes two node-sets |
+ | Addition |
- | Subtraction |
* | Multiplication |
div | Division |
= | Equal |
!= | Not equal |
< | Less than |
<= | Less than or equal to |
> | Greater than |
>= | Greater than or equal to |
or | or |
and | and |
mod | Modulus (division remainder) |
Operator examples
| Expression |
|---|
max(//orderline/item)>5 |
max(//orderline/item)+min(//orderline/item)=4 |
Useful references
For more detailed information go to: