(PHP 4, PHP 5, PHP 7)
xml_set_element_handler — Set up start and end element handlers
$parser
, callable $start_element_handler
, callable $end_element_handler
)
Sets the element handler functions for the XML parser.
start_element_handler and
end_element_handler are strings containing
the names of functions that must exist when xml_parse()
is called for parser.
parserA reference to the XML parser to set up start and end element handler functions.
start_element_handler
The function named by start_element_handler
must accept three parameters:
$parser
, string $name
, array $attribs
)parsernamename, contains the name
of the element for which this handler is called.If case-folding is in effect for this
parser, the element name will be in uppercase letters.
attribsattribs, contains an
associative array with the element's attributes (if any).The keys
of this array are the attribute names, the values are the attribute
values.Attribute names are case-folded on the same criteria as
element names.Attribute values are not
case-folded.
The original order of the attributes can be retrieved by walking
through attribs the normal way, using
each().The first key in the array was the first
attribute, and so on.
Note: Instead of a function name, an array containing an object reference and a method name can also be supplied.
end_element_handler
The function named by end_element_handler
must accept two parameters:
$parser
, string $name
)parsernamename, contains the name
of the element for which this handler is called.If case-folding is in effect for this
parser, the element name will be in uppercase letters.
If a handler function is set to an empty string, or FALSE, the handler
in question is disabled.
Returns TRUE on success or FALSE on failure.
In response to landb at mail dot net...
As the notes mention, you can pass an array that contains the reference to an object and a method name when you need... so you can call methods in your own class as handlers like this:
xml_set_element_handler($parser, array($this,"_startElement"), array($this,"_endElement"));
Hope it helps...
Here is another example of detecting empty elements. I works with libxml2. Note that it handles buffer boundaries.
<?php
$depth = 0; //current depth, used for pretty printing
$empty = false; //whether the tag is empty
$offset = 0; //the index of the start of the current buffer within the stream
function tagStart($parser, $name, array $attribs) {
global $depth, $empty, $data, $offset, $lastchar;
$idx = xml_get_current_byte_index($parser);
/* xml_get_current_byte_index returns index within the streams and not
within the buffer.*/
/* Check if the index is within the buffer. */
if (isset($data[$idx - $offset])) {
$c = $data[$idx - $offset];
} else {
/* If it isn't simple use the last character of the buffer. */
$c = $lastchar;
}
$empty = $c == '/';
echo str_repeat("\t", $depth), "<$name", ($empty ? '/>' : '>'), "\n";
if (!$empty) ++$depth;
}
function tagEnd($parser, $name) {
global $depth, $empty;
if (!$empty) {
--$depth;
echo str_repeat("\t", $depth), "</$name>\n";
} else {
$empty = false;
}
}
$parser = xml_parser_create();
xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, false);
xml_set_element_handler($parser, 'tagStart', 'tagEnd');
$data1 = '
<test>
<empty att="3" />
<nocontent></nocontent>
<content>
<empty/>
<empty/>
</content>
<empty/';
$data2 = '>
<empty att="5" />
</test>
';
$data = &$data1;
$length = strlen($data1);
$lastchar = $data[$length-1];
xml_parse($parser, $data1);
$offset .= $length;
$data = &$data2;
xml_parse($parser, $data2);
This documentation is somewhat awry. I know it's been said many times before, but it bears repeating...
If using PHP4, you may be required to use xml_set_object() instead of calling any of the xml_set_*_handler() functions with a two-item array. It will work fine on PHP5, but move the same code to PHP4 and it will create one copie of $this (even if you use &$this) for each handler you set!
<?php
// This code will fail mysteriously on PHP4.
$this->parser = xml_parser_create();
xml_set_element_handler(
$this->parser,
array(&$this,"start_tag"),
array(&$this,"end_tag")
);
xml_set_character_data_handler(
$this->parser,
array(&$this,"tag_data")
);
?>
<?php
// This code will work on PHP4.
$this->parser = xml_parser_create();
xml_set_object($this->parser,&$this);
xml_set_element_handler(
$this->parser,
"start_tag",
"end_tag"
);
xml_set_character_data_handler(
$this->parser,
"tag_data"
);
?>
I modified the previous script, so that it is associative. I find it more useful that way. BTW I prefer strtolower() things, but that's not mandatory at all.
<?php
$file = "data.xml";
$depth = 0;
$tree = array();
$tree['name'] = "root";
$stack[] = &$tree;
function startElement($parser, $name, $attrs) {
global $depth;
global $stack;
global $tree;
$element = array();
foreach ($attrs as $key => $value) {
$element[strtolower($key)]=$value;
}
end($stack);
$stack[key($stack)][strtolower($name)] = &$element;
$stack[strtolower($name)] = &$element;
$depth++;
}
function endElement($parser, $name) {
global $depth;
global $stack;
array_pop($stack);
$depth--;
}
$xml_parser = xml_parser_create();
xml_set_element_handler($xml_parser, "startElement", "endElement");
if (!($fp = fopen($file, "r"))) {
die("could not open XML input");
}
while ($data = fread($fp, 4096)) {
if (!xml_parse($xml_parser, $data, feof($fp))) {
die(sprintf("XML error: %s at line %d",
xml_error_string(xml_get_error_code($xml_parser)),
xml_get_current_line_number($xml_parser)));
}
}
xml_parser_free($xml_parser);
$tree = end(end($stack));
echo "<pre>";
print_r($tree);
echo "</pre>";
?>
My 25 cents. This example show how to parse a XML in a associative array tree.
<?php
$file = "flow/flow.xml";
$depth = 0;
$tree = array();
$tree['name'] = "root";
$stack[count($stack)] = &$tree;
function startElement($parser, $name, $attrs) {
global $depth;
global $stack;
global $tree;
$element = array();
$element['name'] = $name;
foreach ($attrs as $key => $value) {
//echo $key."=".$value;
$element[$key]=$value;
}
$last = &$stack[count($stack)-1];
$last[count($last)-1] = &$element;
$stack[count($stack)] = &$element;
$depth++;
}
function endElement($parser, $name) {
global $depth;
global $stack;
array_pop($stack);
$depth--;
}
$xml_parser = xml_parser_create();
xml_set_element_handler($xml_parser, "startElement", "endElement");
if (!($fp = fopen($file, "r"))) {
die("could not open XML input");
}
while ($data = fread($fp, 4096)) {
if (!xml_parse($xml_parser, $data, feof($fp))) {
die(sprintf("XML error: %s at line %d",
xml_error_string(xml_get_error_code($xml_parser)),
xml_get_current_line_number($xml_parser)));
}
}
xml_parser_free($xml_parser);
$tree = $stack[0][0];
echo "<pre>";
print_r($tree);
echo "</pre>";
I ran into the same problem with 'ibjoel at hotmail dot com' in regards to self-closing tags, and found that the script that he/she wrote did not work as I expected.
I played around with some of php's functions and examples and compiled something, which may not be the neatest solution, but it works for the data that 'ibjoel at hotmail dot com' provided.
The data needs to be read from a file though, so the fp can be utilised. It still uses the xml_get_current_byte_index(resource parser) trick, but this time, I check for the last 2 character before the index and test if it's "/>".
<?php
/* myxmltest.xml:
<normal_tag>
<self_close_tag />
data
<normal_tag>data
<self_close_tag attr="value" />
</normal_tag>
data
<normal_tag></normal_tag>
</normal_tag>
*/
//## Global Variables ##//
$file = "myxmltest.xml";
$character_data_on = false;
$tag_complete = true;
function startElement($parser, $name, $attrs)
{
global $character_data_on;
global $tag_complete;
echo "<<font color=\"#0000cc\">$name</font>";
//## Print the attributes ##//
if (sizeof($attrs)) {
while (list($k, $v) = each($attrs)) {
echo " <font color=\"#009900\">$k</font>=\"<font
color=\"#990000\">$v</font>\"";
}
}
//## Tag is still still incomplete,
//## will be completed at either endElement or characterData ##//
$tag_complete = false;
$character_data_on = false;
}
function endElement($parser, $name)
{
global $fp;
global $character_data_on;
global $tag_complete;
//#### Test for self-closing tag ####//
//## xml_get_current_byte_index(resource parser) when run in this
//## function, gives the index at (indicated by *):
//## for self closing tag: <br />*
//## for individual closing tag: <div>character data*</div>
//## So to test for self-closing tag, we can just test for the last 2
//## characters from the index
//###################################//
if (!$character_data_on) {
//## Record current fp position ##//
$temp_fp = ftell($fp);
//## Point fp to 2 bytes before the end element byte index ##//
$end_element_byte_index = xml_get_current_byte_index($parser);
fseek($fp,$end_element_byte_index-2);
//## Gets the last 2 characters before the end element byte index ##//
$validator = fgets($fp, 3);
//## Restore fp position ##//
fseek($fp,$temp_fp);
//## If the last 2 character is "/>" ##//
if ($validator=="/>") {
//// Complete the self-closing tag ////
echo " />";
//// Otherwise it is an individual closing tag ////
} else echo "></<font color=\"#0000cc\">$name</font>>";
$tag_complete = true;
} else echo "</<font color=\"#0000cc\">$name</font>>";
$character_data_on = false;
}
function characterData($parser, $data)
{
global $character_data_on;
global $tag_complete;
if ((!$character_data_on)&&(!$tag_complete)) {
echo ">";
$tag_complete = true;
}
echo "<b>$data</b>";
$character_data_on = true;
}
$xml_parser = xml_parser_create();
xml_parser_set_option($xml_parser, XML_OPTION_CASE_FOLDING, false);
xml_set_element_handler($xml_parser, "startElement", "endElement");
xml_set_character_data_handler($xml_parser, "characterData");
if (!($fp = fopen($file, "r"))) {
die("could not open XML input");
}
echo "<pre>";
while ($file_content = fread($fp, 4096)) {
if (!xml_parse($xml_parser, $file_content, feof($fp))) {
die(sprintf("XML error: %s at line %d",
xml_error_string(xml_get_error_code($xml_parser)),
xml_get_current_line_number($xml_parser)));
}
}
echo "</pre>";
xml_parser_free($xml_parser);
?>
The method that 'ibjoel at hotmail dot com' have described requires libxml2 as the xml parser, it does not work with expat. For a brief explanation, see xml_get_current_byte_index.
<html>
<head>
<title>SAX Demonstration</title>
<META HTTP-EQUIV='Content-type' CONTENT='text/html; charset=euc-kr'>
</head>
<body>
<h1>RSS ������</h1>
<?php
$file = "data.xml";
$currentTag = "";
$currentAttribs = "";
function startElement($parser, $name, $attribs)
{
global $currentTag, $currentAttribs;
$currentTag = $name;
$currentAttribs = $attribs;
switch ($name) {
default:
echo("<b><$name></b><br>");
break;
}
}
function endElement($parser, $name)
{
global $currentTag;
switch ($name) {
default:
echo("<br><b></$name></b><br><br>");
break;
}
$currentTag = "";
$currentAttribs = "";
}
function characterData($parser, $data)
{
global $currentTag;
switch ($currentTag) {
case "link":
echo("<a href=\"$data\">$data</a>\n");
break;
case "title":
echo("title : $data");
break;
default:
echo($data);
break;
}
}
$xmlParser = xml_parser_create();
$caseFold = xml_parser_get_option($xmlParser,
XML_OPTION_CASE_FOLDING);
$targetEncoding = xml_parser_get_option($xmlParser,
XML_OPTION_TARGET_ENCODING);
if ($caseFold == 1) {
xml_parser_set_option($xmlParser, XML_OPTION_CASE_FOLDING, false);
}
xml_set_element_handler($xmlParser, "startElement", "endElement");
xml_set_character_data_handler($xmlParser, "characterData");
if (!($fp = fopen($file, "r"))) {
die("Cannot open XML data file: $file");
}
while ($data = fread($fp, 4096)) {
if (!xml_parse($xmlParser, $data, feof($fp))) {
die(sprintf("XML error: %s at line %d",
xml_error_string(xml_get_error_code($xmlParser)),
xml_get_current_line_number($xmlParser)));
xml_parser_free($xmlParser);
}
}
xml_parser_free($xmlParser);
?>
</table>
</body>
</html>
If you are using a class for xml parsing, and want to check the return value of xml_set_element_handler in case it fails, you must do this outside of the class's constructor. Inside the constructor, PHP-4.0.5 will die.
Basically, put all your xml initialisation code in another function of the class, and keep it out of the constructor.
Example below (BadParser) works fine with some changes.
xml_set_element_handler ( $parser, array ( &$this, 'tagStart' ), array ( &$this, 'tagEnd' ) );
xml_set_character_data_handler ( $parser, array ( &$this, 'tagContent' ) );
I noticed that in the example below, and all the examples I've seen on this site for viewing xml in html, the look of self closing tags such as <br /> are not preserved. The parser cannot distinguish between <tag /> and <tag></tag>, and if your start and end element functions are like these examples, both instances will be output with both an indvidual start and end tag. I needed to preserve self-closing tags and it took me a while to figure out this work around. Hope this helps someone...
The start tag is left open, and then completed by it's first child, the next start tag or its end tag. The end tag will complete with " />", or </tag> depending on the number of bytes between the start and end tags in the parsed data.
<?php
//$data=filepath or string
$data=<<<DATA
<normal_tag>
<self_close_tag />
data
<normal_tag>data
<self_close_tag attr="value" />
</normal_tag>
data
<normal_tag></normal_tag>
</normal_tag>
DATA;
function startElement($parser, $name, $attrs)
{
xml_set_character_data_handler($parser, "characterData");
global $first_child, $start_byte;
if($first_child) //close start tag if neccessary
echo "><br />";
$first_child=true;
$start_byte=xml_get_current_byte_index ($parser);
if(count($attrs)>=1){
foreach($attrs as $x=>$y){
$attr_string .= " $x=\"$y\"";
}
}
echo htmlentities("<{$name}{$attr_string}"); //unclosed starttag
}
function endElement($parser, $name)
{
global $first_child, $start_byte;
$byte=xml_get_current_byte_index ($parser);
if($byte-$start_byte>2){ //if end tag is more than 2 bytes from start tag
if($first_child) //close start tag if neccessary
echo "><br />";
echo htmlentities("</{$name}>")."<br />"; //individual end tag
}else
echo " /><br />"; // self closing tag
$first_child=false;
}
function characterData($parser, $data)
{
global $first_child;
if($first_child) //if $data is first child, close start tag
echo "><br />";
if($data=trim($data))
echo "<font color='blue'>$data</font><br />";
$first_child=false;
}
function ParseData($data)
{
$xml_parser = xml_parser_create();
xml_set_element_handler($xml_parser, "startElement", "endElement");
xml_parser_set_option($xml_parser,XML_OPTION_CASE_FOLDING,0);
if(is_file($data))
{
if (!($fp = fopen($file, "r"))) {
die("could not open XML input");
}
while ($data = fread($fp, 4096)) {
if (!xml_parse($xml_parser, $data, feof($fp))) {
$error=xml_error_string(xml_get_error_code($xml_parser));
$line=xml_get_current_line_number($xml_parser);
die(sprintf("XML error: %s at line %d",$error,$line));
}
}
}else{
if (!xml_parse($xml_parser, $data, 1)) {
$error=xml_error_string(xml_get_error_code($xml_parser));
$line=xml_get_current_line_number($xml_parser);
die(sprintf("XML error: %s at line %d",$error,$line));
}
}
xml_parser_free($xml_parser);
}
ParseData($data);
?>
It seems that the tag handlers don't block on one another (the end handler is called whether or not the begin handler has finished). this can put you in a tight spot if you don't realize it while planning your app.
You CAN use classes to parse XML. Just take a look at the following function:
xml_set_object
It seems that characterData() gets characters in chuncks of 1024; therefore if you have string of characters between you tags that is longer than 1024 then characterData() will be called more that once for single pair of tags. I don't know if this feature(bug?) is documented anywhere, I just wanted to warn everyone about this; it had tripped me. I use php 4.3.10 on Linux.
In response to aw at avatartechnology dot com...
In response to landb at mail dot net...
When your functions are in an object:
Careful ! Don't forget to add: & (reference) to your parameters.
xml_set_element_handler($parser, array(&$this,"_startElement"), array(&$this,"_endElement"));
--> xmlparse will work on your object (good).
instead of:
xml_set_element_handler($parser, array($this,"_startElement"), array($this,"_endElement"));
---> xmlparse will work on a COPY of your object (often bad)
Vin-s
(sorry for my english)
