XPath

XPath (XML Path Language) is a query language for selecting nodes and values from XML documents. In Apidog, XPath is used to extract data from XML API responses, validate XML structures, and create assertions for XML-based APIs.

You can use XPath to select nodes or sets of nodes in an XML document by following a path or series of steps through the document hierarchy.

XML Example

We will use this XML document in the following examples:

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
  <book>
    <title lang="eng">Harry Potter</title>
    <price>29.99</price>
  </book>
  <book>
    <title lang="eng">Learning XML</title>
    <price>39.95</price>
  </book>
</bookstore>

Node Selection

XPath allows you to select nodes or sets of nodes in an XML document by following a path or steps. Below are some of the most common path expressions:

Expression	Description
`nodename`	Select all the children of this node
`/`	Select from the root node
`//`	Select nodes in the document from the current node that matches the selection, regardless of their positions
`.`	Select the current node
`..`	Select the parent node of the current node
`@`	Select an attribute

Path Expression Examples

The following table shows path expressions and their results based on the example XML:

Path Expression	Result
`bookstore`	Select all children of the bookstore element
`/bookstore`	Select the root element bookstore. If the path starts with a forward slash ( / ), then this path always represents an absolute path to an element
`bookstore/book`	Select all book elements that are children of the bookstore
`//book`	Select all book elements regardless of their position in the document
`bookstore//book`	Select all book elements that are children of bookstore elements, regardless of where they are located under the bookstore
`//@lang`	Select all attributes named lang

Absolute vs Relative Paths

Paths starting with / are absolute (from root), while paths without / are relative to the current node.

Predicates

You can use predicates to find a specific node or a node containing a specified value. Predicates are enclosed in square brackets and allow for powerful filtering.

Predicate Examples

Path Expression	Result
`/bookstore/book[1]`	Select the first book element of the bookstore child elements
`/bookstore/book[last()]`	Select the last book element of the bookstore child elements
`/bookstore/book[last()-1]`	Select the second to the last book element of the bookstore child elements
`/bookstore/book[position()<3]`	Select the first two book elements of the bookstore child elements
`//title[@lang]`	Select all title elements that have an attribute named lang
`//title[@lang='eng']`	Select all title elements that have a lang attribute with the value eng
`/bookstore/book[price>35.00]`	Select all book elements of the bookstore with the value of the price element greater than 35.00
`/bookstore/book[price>35.00]//title`	Select all the title elements of the book element in the bookstore with the price element greater than 35.00

Predicate Indexing

XPath uses 1-based indexing for predicates, unlike JSONPath which uses 0-based indexing. The first element is [1], not [0].

Selecting Unknown Nodes

The XPath wildcard can be used to select unknown XML elements without knowing their exact names.

Wildcard Syntax

Wildcard	Description
`*`	Match any element node
`@*`	Match any attribute node
`node()`	Match any type of node

Wildcard Examples

Path Expression	Result
`/bookstore/*`	Select all child elements of the bookstore element
`//*`	Select all elements in the document
`//title[@*]`	Select all title elements with attributes

Wildcard Usage

Wildcards are useful when working with dynamic XML structures or when you want to select all elements regardless of their names.

Select Multiple Paths

You can select several paths by using the | operator in a path expression, allowing you to combine multiple selections.

Multiple Path Examples

Path Expression	Result
`//book/title \| //book/price`	Selects all title and price elements of the book element
`//title \| //price`	Select all title and price elements in the document
`/bookstore/book/title \| //price`	Select all the title elements of the book element of the bookstore element and all the price elements in the document

Use Cases in Apidog

XPath is particularly useful in Apidog for:

XML Response Validation: Extract specific values from XML API responses to verify correctness

SOAP API Testing: Parse and validate SOAP responses

Dynamic Variables: Store extracted XML values for use in subsequent requests

Test Assertions: Create assertions based on XML response data

Data Extraction: Pull specific fields from complex nested XML structures

XML vs JSON

While JSON is more common in modern APIs, many legacy systems and SOAP-based services still use XML. XPath is essential for testing these APIs.

References

W3C XPath Specification

XPath Tutorial - W3Schools

XPath Tester

XML Example#

Node Selection#

Path Expression Examples#

Predicates#

Predicate Examples#

Selecting Unknown Nodes#

Wildcard Syntax#

Wildcard Examples#

Select Multiple Paths#

Multiple Path Examples#

Use Cases in Apidog#

References#

XML Example

Node Selection

Path Expression Examples

Predicates

Predicate Examples

Selecting Unknown Nodes

Wildcard Syntax

Wildcard Examples

Select Multiple Paths

Multiple Path Examples

Use Cases in Apidog

References