XPath - A Fun Walk With A Powerful Query Language

xpath.php

<?php
require_once 'Console/Table.php';
$groupsDoc = new DOMDocument();
$groupsDoc->load("groups.xml");
$groupsDoc->formatOutput = TRUE;
file_put_contents("readable-groups.xml",$groupsDoc->saveXML());
$xpath = new DOMXpath($groupsDoc);
/*******************************************************************************








                  __  __    ____       _       _____    _   _
                  \ \/"/  U|  _"\ uU  /"\  u  |_ " _|  |'| |'|
                  /\  /\  \| |_) |/ \/ _ \/     | |   /| |_| |\
                 U /  \ u  |  __/   / ___ \    /| |\  U|  _  |u
                  /_/\_\   |_|     /_/   \_\  u |_|U   |_| |_|
                ,-,>> \\_  ||>>_    \\    >>  _// \\_  //   \\
                 \_)  (__)(__)__)  (__)  (__)(__) (__)(_") ("_)

                   A Fun Walk With A Powerful Query Language

                                  Allan Chappell

                                  AllPlayers.com
                                      Eat n'
                                       Geek

                                September 26, 2012




********************************************************************************




                            ==WHAT IS XPATH?==

* XPath is a syntax for defining parts of an XML document
* XPath uses path expressions to navigate in XML documents
* XPath contains a library of standard functions


                            ==STANDARDIZED==

Check out the standard at http://www.w3.org/TR/xpath/

                        ==XPath Path Expressions==

* XPath uses path expressions to select nodes or node-sets in an XML document.
* These path expressions look very much like a traditional computer file system.










********************************************************************************
                            ==XPATH TERMINOLOGY==

* NODES (7 of these)
  - element
  - attribute
  - text
  - namespace
  - processing-instruction
  - comment
  - document nodes

<?xml version="1.0" encoding="utf-8"?>  <= Processing Instruction
<!-- Comment -->
<result is_array="true">   <============== Root Element Node with Attribute
  <item>
    <uuid>499f7aa0-573f-11e1-887f-12313d2a2278  <==Text     </uuid>
    <title>Spartans (Rakoski)</title>
    <description>Town North YMCA Soccer, 2012 Spring Flag Football</description>
    <location>
      <street>4332 Northaven Road</street>
      <city>Dallas</city>
      <state>TX</state>
      <zip>75229</zip>
      <country>us</country>
      <latitude>32.901306</latitude>
      <longitude>-96.835542</longitude>
    </location>
  </item>
</result>
********************************************************************************


                            ==NODE RELATIONSHIPS==

* Parent - Each node has one of these. The root node is a child of the document.
* Children - Nodes can have 0 or more of these.
* Siblings - Nodes that have the same parent.
* Ancestors - A node's parent's parent and that node's parent, etc.
* Decendents - A node's children's children and that node's child etc.


<result is_array="true">   <============================= location's Ancestor
  <item>                   <============================= uuid's Parent
    <uuid>499f7aa0-573f-11e1-887f-12313d2a2278</uuid> <== title's Sibling
    <title>Spartans (Rakoski)</title> <================== item's Child
    <description>Town North YMCA Soccer, 2012 Spring Flag Football</description>
    <location>
      <street>4332 Northaven Road</street> <============= result's Decendant
      <city>Dallas</city>
      <state>TX</state>
      <zip>75229</zip>
      <country>us</country>
      <latitude>32.901306</latitude>
      <longitude>-96.835542</longitude>
    </location>
  </item>
</result>


********************************************************************************
                               ==XPATH SYNTAX==

  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
*/

$results = array();

// Returns all nodes with the name item.
// NOTE: This form is in context.
$results['All Items']             = $xpath->query('item');
// Returns the root node result.
// NOTE: / means absolute path!
$results['Root Result Node']      = $xpath->query('/result');
// Returns all items' uuids.
$results["All Items' Uuids"]      = $xpath->query('item/uuid');
// Returns all uuids no matter where they are.
$results['All Uuids']             = $xpath->query('//uuid');
// Returns all uuids under items.
$results['All Uuids Under Items'] = $xpath->query('//item//uuid');
// An attribute
$results['IsArray Attribute']     = $xpath->query('/result/@is_array');
display_results($results);

/*******************************************************************************

                                ==PREDICATES==

Used to find a node that has a specific value or contains another specific node.

NOTE: There is a heavy use of functions in predicates. More on XPATH functions
      later.

ANOTHER NOTE: It is worth noting that you are not limited to just one of these.
              It is perfectly legal to have:
                /result/item[2][/active/text()="active"]
              This would get the 2nd item that is "active"
*/

$results = array();

// [#] selects the element in that position
$results['First Item in Result']  = $xpath->query('/result/item[1]');
// [last()] selects the last element that would have been returned
$results['Last Item in Result']   = $xpath->query('/result/item[last()]');
// [xpath-query] selects the node that contains those nodes
$results['Item From Dallas'] = $xpath->query('item[location/city/text()="Dallas"]');
// getting complicated!
$results["Items' First Group Above"] = $xpath->query('/result/item[/result/item/groups_above_uuid/item[1]/text() = uuid/text()]');
display_results($results);



/*******************************************************************************

                          ==SELECTING UNKNOWN NODES==

  *           Matches any element node
  @*          Matches any attribute node
  node()      Matches any node type

*/

// Great for traversing through everything, or gathering like attributes on
// different item types.

//For all items in Dallas, get all the location information

echo center_text('Location Information for Dallas Based Items') . "\n";
$tbl = new Console_Table();
foreach ($xpath->query('item[location/city/text()="Dallas"]/location/*') as $item) {
  $tbl->addRow(array($item->nodeName, $item->textContent));
}
echo $tbl->getTable();
echo "\n Press Enter to Continue:\n";
fgets(STDIN);
/*






/*******************************************************************************

                              ==XPATH OPERATORS==

  |         Computes two node-sets
  +         Addition       6 + 4             10
  -         Subtraction    6 - 4              2
  *         Multiplication 6 * 4             24
  div       Division       8 div 4            2
  =         Equal          price=9.80        true if price is 9.80
                                             false if price is 9.90
  !=        Not equal      price!=9.80       true if price is 9.90
                                             false if price is 9.80
  <         Less than      price<9.80        true if price is 9.00
                                             false if price is 9.80
  <=        Less than      price<=9.80       true if price is 9.00
            or equal to                      false if price is 9.90
  >         Greater than   price>9.80        true if price is 9.90
                                             false if price is 9.80
  >=        Greater than   price>=9.80       true if price is 9.90
            or equal to                      false if price is 9.70
  or        or             price=9.80        true if price is 9.80
                           or price=9.70     false if price is 9.50
  and       and            price>9.00 and    true if price is 9.80
                           price<9.90        false if price is 8.50
  mod       Modulus
            (division      5 mod 2           1
            remainder)


/*******************************************************************************

                              ==COMMON FUNCTIONS==

fn:concat(string,string,...)            Returns the concatenation of the strings

fn:string-join((string,string,...),sep) Returns a string created by i
                                        concatenating the string arguments and 
                                        using the sep argument as the separator

fn:normalize-space(string)              Removes leading and trailing spaces from
                                        the specified string, and replaces all 
                                        internal sequences of white space with 
                                        one and returns the result. If there is
                                        no string argument it does the same on 
                                        the current node

fn:contains(string1,string2)            Returns true if string1 contains 
                                        string2, otherwise it returns false

fn:position()                           Returns the index position of the node 
                                        that is currently being processed 

fn:last()                               Returns the number of items in the 
                                        processed node list





/*******************************************************************************

                             ==USES FOR XPATH==

 * Anything XML like:
     - RSS Feeds
     - XML APIs
     - Web pages
     - Microsoft Office File Manipulation

 * Selenium Testing



                        ==DEMO OF POWERPOINT TO HTML==















/*******************************************************************************








   ___     _   _ U _____ u ____     _____             U  ___ u  _   _    ____
  / " \ U |"|u| |\| ___"|// __"| u |_ " _|     ___     \/"_ \/ | \ |"|  / __"| u
 | |"| | \| |\| | |  _|" <\___ \/    | |      |_"_|    | | | |<|  \| |><\___ \/
/| |_| |\ | |_| | | |___  u___) |   /| |\      | | .-,_| |_| |U| |\  |u u___) |
U \__\_\u<<\___/  |_____| |____/>> u |_|U    U/| |\u\_)-\___/  |_| \_|  |____/>>
   \\// (__) )(   <<   >>  )(  (__)_// \\_.-,_|___|_,-.  \\    ||   \\,-.)( (__)
  (_(__)    (__) (__) (__)(__)    (__) (__)\_)-' '-(_/  (__)   (_")  (_/(__)














/******************************************************************************/
function display_results($results) {

  foreach ($results as $name => $resultList) {
    echo center_text($name) . "\n";
    $tbl = new Console_Table();
    $tbl->setHeaders(
      array('XPath', 'Value')
    );
    $firstNode = NULL;
    foreach ($resultList as $resultNode) {
      // Get the first Node so we can show it's XML
      if(empty($firstNode)) {
        $firstNode = $resultNode;
      }
      // Get Text Node
      $xpath = new DOMXpath($resultNode->ownerDocument);
      $textResult = $xpath->evaluate('text()',$resultNode);
      $text = "";
      if($textResult->length != 0) {
        $text = $xpath->evaluate('text()',$resultNode)->item(0)->nodeValue;
      }
      else if ($resultNode instanceof DOMAttr) {
        $text = $resultNode->value;
      }
      $tbl->addRow(array($resultNode->getNodePath(), $text));
    }
  echo $tbl->getTable();
  echo "\n XML of the first Node: \n";
  echo $firstNode->ownerDocument->saveXML($firstNode);
  echo "\n Press Enter to Continue:\n";
  fgets(STDIN);
  }
}
function center_text($word){
    $tot_width = 80;
    $symbol = "-";
    $middle = round($tot_width/2);
    $length_word = strlen($word);
    $middle_word = round($length_word / 2);
    $last_position = $middle + $middle_word;
    $number_of_spaces = $middle - $middle_word;

    $result = sprintf("%'{$symbol}{$last_position}s", $word);
        for ($i = 0; $i < $number_of_spaces; $i++){
            $result .= "$symbol";
        }
    return $result;
}

Well done, sir!

Thank you. Been a long time since I looked at this. 10 years old and I bet it still would run!