apex-xpath

A utility class for Salesforce Apex that lets you easily query an XML DOM structure using a simple subset of XPath syntax.

To Use

1. Create a new XPath object from an XML string, or if you've already created a Dom.Document then pass that to the constructor.

2. Call find, findFirst, getText, or getTextList, passing it an XPath expression and optionally a node from the DOM to start the search. (The default is to start the search at the root element).

XPath Syntax Supported

Apex-xpath supports a simple subset of XPath 1.0 "abbreviated" syntax.

An xpath consists of one or more location steps. Each location step starts with a "/" (except the initial step, if it's a relative path), a "node test", and an optional "predicate":

A node test is the part that specifies which tagnames to look for at a given point in the path:

• /tagname The most common test is a plain tagname.
• /* A tagname can be "*", meaning any immediate child.
• /namespace:tagname You can include a namespace in the node test.
• /tagname/tagname Paths can be up to 50 levels deep. (Limitation of Dom.Document class)
• ./child/grandchild A tagname of "." refers to the current element.
• ../sibling/nephew, ../../aunt/cousin A tagname of ".." refers to the current element's parent. Useful for getting siblings, cousins, etc.

A predicate is a filter expression inside "[ ]":

• /tagname[1] Filter the results of the node test by "nth-result" (using 1-relative index)
• /tagname[@id] Filter by "has this attribute"
• /tagname[@id=12345] Filter by "attribute x = value"
• /tagname[@id="12345"] Filter by "attribute x = value"

Example

String xml = some huge SOAP response containing orders;
XPath xp = new XPath(xml);
Dom.XmlNode[] orders = xp.find('/soapenv:Envelope/soapenv:Body/searchOrdersResponse/orders/order');

// If an order contains line items, here are a couple different ways to get their SKUs...
for (Dom.XmlNode order : orders) {
    String[] Skus = xp.getTextList(order, 'lineitem/id');
    String SkuCsv = xp.getText(order, ',', 'lineItem/id');
}

The Properties

Dom.Document doc

The Dom.Document that was passed in or that we created from the XML source.

Dom.XmlNode root

The root node in the Dom.Document.

The Methods

In all the methods below that take an optional start parameter, the default is to start the search at the root node.

XPath (String xmlsrc)

Creates an XPath object from a snippet of XML.

XPath (Dom.Document doc)

Creates an XPath object from a Dom.Document object that you've already created.

Dom.XmlNode[] find (String path)

Dom.XmlNode[] find (Dom.XmlNode start, String path)

Returns a List of all the nodes that are described by the path.

Dom.XmlNode findFirst (String path)

Dom.XmlNode findFirst (Dom.XmlNode start, String path)

Returns the first node in the DOM that is described by the path.

String getText (String path)

String getText (Dom.XmlNode start, String path)

Returns the string content of the first node in the DOM that is described by the path.

String getText (String delimiter, String path)

String getText (Dom.XmlNode start, String delimiter, String path)

Returns the string contents of all the nodes that are described by the path, separated by the delimiter.

String[] getTextList (String path)

String[] getTextList (Dom.XmlNode start, String path)

Returns the string contents of all the nodes that are described by the path, in a List.

Submitting Pull Requests

If you've fixed a bug or came up with a great addition to the API, I welcome your code submissions! To make things smoother, please follow these guidelines:

• Create an Issue for the bug you're fixing or feature you're adding, if there isn't one already. This is especially important if you're adding a new feature or changing the API - the userbase needs to be able to discuss it first!
• If someone is proposing a new feature or a change to the existing API, please chime in in the comments for that issue. It's important that the library evolves in a way that the userbase feels is useful and straightforward to use.
• The default branch to submit pull requests to will normally be the current version under development. We'll try to release updates to Master in a controlled manner.
• So far the project's coding conventions are rather straightforward:
  • K&R bracing (only because it's so ubiquitous, not because it's any good!).
  • Use the "[]" style when declaring Lists.
  • For each new method, write a comment block with a short description of what it does, what its parameters mean and their defaults, what it returns, and any caveats/gotchas/assumptions that the caller should know about.
  • If you're updating a method please review the comment block & update it if appropriate.