Use xml_parse to parse dynamically generated XML data

In PHP, there are many ways to parse XML data, such as using DOM, SimpleXML, or XML Parser. This article will introduce how to use the underlying xml_parse() function in conjunction with the XML parser to process dynamically generated XML data .

What is xml_parse() ?

xml_parse() is one of PHP's XML extension functions, which is used to feed XML strings into the parser for parsing. It is used in combination with functions such as xml_parser_create() , xml_set_element_handler() , and is suitable for handling scenarios where the label structure needs to be finely controlled.

Sample Scenario: Get XML data from a remote address

Suppose you have an interface that generates XML dynamically:

 https://api.m66.net/data/feed.xml

You want to get XML data from this address and parse the title and link fields under the <item> tag.

Sample code

 <?php

// Initialization parser
$parser = xml_parser_create();

// Arrays for storing data
$parsedData = [];
$currentTag = '';
$currentItem = [];

// Define the start tag processor
function startElement($parser, $name, $attrs) {
    global $currentTag, $currentItem;
    $currentTag = strtolower($name);
    if ($currentTag === 'item') {
        $currentItem = [];
    }
}

// Define the end tag processor
function endElement($parser, $name) {
    global $currentTag, $currentItem, $parsedData;
    if (strtolower($name) === 'item') {
        $parsedData[] = $currentItem;
    }
    $currentTag = '';
}

// Define character data processor
function characterData($parser, $data) {
    global $currentTag, $currentItem;
    $data = trim($data);
    if (!$data) return;

    if ($currentTag === 'title') {
        $currentItem['title'] = (isset($currentItem['title']) ? $currentItem['title'] : '') . $data;
    } elseif ($currentTag === 'link') {
        $currentItem['link'] = (isset($currentItem['link']) ? $currentItem['link'] : '') . $data;
    }
}

// Set up the processor
xml_set_element_handler($parser, "startElement", "endElement");
xml_set_character_data_handler($parser, "characterData");

// Get from remote XML content
$url = "https://api.m66.net/data/feed.xml";
$xmlData = file_get_contents($url);

if (!$xmlData) {
    die("Unable to obtain XML data");
}

// Start parsing
if (!xml_parse($parser, $xmlData, true)) {
    die(sprintf("XML mistake: %s In the %d OK",
        xml_error_string(xml_get_error_code($parser)),
        xml_get_current_line_number($parser)));
}

// Release parser resources
xml_parser_free($parser);

// Output result
echo "<pre>";
print_r($parsedData);
echo "</pre>";
?>

Output example

 Array
(
    [0] => Array
        (
            [title] => Sample title1
            [link] => https://www.m66.net/item/123
        )
    [1] => Array
        (
            [title] => Sample title2
            [link] => https://www.m66.net/item/456
        )
)

summary

Use xml_parse() to provide complete control over XML data structures and is suitable for complex or non-standard structure XML files. Although not as concise as SimpleXML, it is very useful for scenarios where custom processing flow is required.