Node:query()

Node:query(path)method

Executes a path expression (XPath 1.0 and XSLT 1.0 standards) relative to this node and returns the results as a table of Node, or nil if no match is found.

Parameters

path

A string path expression to evaluate.

Return value

Returns the first matching Node, or nil if no match is found.

Example


local xml = require("xml")

local root = xml.encode([[
<library>
  <book id="1"><title>WhiteSnow</title><author>Grimm brothers</author></book>
  <book id="2"><title>Cinderella</title><author>Charles Perrault</author></book>
</library>
]])

local function query_and_print(xpath)
    local nodes = root:query(xpath)
    print('XPath query : "'..xpath..'"')
    if nodes == nil then
        print("\tNo node found")
    else
        for node in each(nodes) do
            print("", node)
        end
    end
end

-- should print 2 nodes <book>
query_and_print("//book")

--- selects all <title> nodes inside <book>
--> should print 2 nodes (WhiteSnow and Cinderella)
query_and_print("//book/title")

--- selects all <author> nodes
--> should print 2 nodes(Grimm brothers and Charles Perrault)
query_and_print("//author")

--- selects all <book> nodes with attribute id="1"
--> should print 1 node (the first book)
query_and_print("//book[@id='1']")

--- selects <title> with the title text "Cinderella"
--> should print 1 node (the second book)
query_and_print("//book/title[text()='Cinderella']")

--- selects <book> whose author is "Grimm brothers"
--> should print 1 node (the second book)
query_and_print("//book[author='Grimm brothers']")