XPath short description
(see https://www.w3schools.com/xml/xpath_intro.asp )
- Selecting XML nodes
XPath uses path expressions to select nodes in an XML document. The node is selected by following a path or steps. The most useful path expressions are listed below:
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 |
- Predicates
Predicates are used to find a specific node or a node that contains a specific value. Predicates are always embedded in square brackets.
In the table below we have listed some path expressions with predicates and the result of the expressions:
|
|
/bookstore/book[1] |
Selects the first book element that is the child of the bookstore element. |
/bookstore/book[last()] |
Selects the last book element that is the child of the bookstore element |
/bookstore/book[last()-1] |
Selects the last but one book element that is the child of the bookstore element |
/bookstore/book[position()<3] |
Selects the first two book elements that are children of the bookstore element |
//title[@lang] |
Selects all the title elements that have an attribute named lang |
//title[@lang='en'] |
Selects all the title elements that have a "lang" attribute with a value of "en" |
/bookstore/book[price>35.00] |
Selects all the book elements of the bookstore element that have a price element with a value greater than 35.00 |
/bookstore/book[price>35.00]/title |
Selects all the title elements of the book elements of the bookstore element that have a price element with a value greater than 35.00 |
- Selecting Unknown Nodes
XPath wildcards can be used to select unknown XML nodes.
|
|
* |
Matches any element node |
@* |
Matches any attribute node |
node() |
Matches any node of any kind |
In the table below we have listed some path expressions and the result of the expressions:
|
|
/bookstore/* |
Selects all the child element nodes of the bookstore element |
//* |
Selects all elements in the document |
//title[@*] |
Selects all title elements which have at least one attribute of any kind |
- Selecting Several Paths
By using the | operator in an XPath expression you can select several paths.
In the table below we have listed some path expressions and the result of the expressions:
//book/title | book/price |
Selects all the title AND price elements of all book elements |
//title | //price |
Selects all the title AND price elements in the document |
/bookstore/book/title | //price |
Selects all the title elements of the book element of the bookstore element AND all the price elements in the document |
- XPath Operators
Below is a list of the operators that can be used in XPath expressions:
| | Computes two node-sets | //book | //cd |
+ |
Addition |
6 + 4 |
- |
Subtraction |
6 - 4 |
* |
Multiplication |
6 * 4 |
div |
Division |
8 div 4 |
= |
Equal |
price=9.80 |
!= | Not equal | price!=9.80 |
< |
Less than |
price<9.80 |
<= |
Less than or equal to |
price<=9.80 |
> |
Greater than |
price>9.80 |
>= |
Greater than or equal to |
price>=9.80 |
or |
or |
price=9.80 or price=9.70 |
and |
and |
price>9.00 and price<9.90 |
mod |
Modulus (division remainder) |
5 mod 2 |