XPath short description
1 person viewed(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| 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 |